A Case of Autosomal Dominant Polycystic Kidney Disease With Resolution of Massive Pericardial Effusion After Renal Transcatheter Artery Embolization

A 68-year-old woman being treated with hemodialysis for autosomal dominant polycystic kidney disease was admitted for progressive dyspnea over 6 months. On chest radiography, her cardiothoracic ratio had increased from 52.2% 6 months prior, to 71%, and echocardiography revealed diffuse pericardial effusion and right ventricular diastolic insufficiency. A resultant pericardial tamponade was thought to be the cause of the patient's dyspnea, and therefore a pericardiocentesis was performed, with a total of 2,000mL of fluid removed. However, 21 days later the same amount of pericardial fluid had reaccumulated. The second pericardiocentesis was performed, followed by transcatheter renal artery embolization (TAE). The kidneys, which were hard on palpation before TAE, softened immediately after TAE. After resolution of the pericardial effusion was confirmed, the patient was discharged after 24 days in hospital. Twelve months later, the patient was asymptomatic, the cardiothoracic ratio decreased to 48% on chest radiography and computed tomography revealed no reaccumulation of pericardial effusion. This case illustrates a potential relationship between enlarged kidneys in autosomal dominant polycystic kidney disease and pericardial effusion.

Deep learning-based automated kidney and cyst segmentation of autosomal dominant polycystic kidney disease using single vs. multi-institutional data

PURPOSE

This study aimed to investigate if a deep learning model trained with a single institution's data has comparable accuracy to that trained with multi-institutional data for segmenting kidney and cyst regions in magnetic resonance (MR) images of patients affected by autosomal dominant polycystic kidney disease (ADPKD).

METHODS

We used TensorFlow with a Keras custom UNet on 2D slices of 756 MRI images of kidneys with ADPKD obtained from four institutions in the Consortium for Radiologic Imaging Studies of Polycystic Kidney Disease (CRISP) study. The ground truth was determined via a manual plus global thresholding method. Five models were trained with 80 % of all institutional data (n = 604) and each institutional data (n = 232, 172, 148, or 52), respectively, and validated with 10 % and tested on an unseen 10 % of the data. The model's performance was evaluated using the Dice Similarity Coefficient (DSC).

RESULTS

The DSCs by the model trained with all institutional data ranged from 0.92 to 0.95 for kidney image segmentation, only 1-2 % higher than those by the models trained with single institutional data (0.90-0.93).In cyst segmentation, however, the DSCs by the model trained with all institutional data ranged from 0.83 to 0.89, which were 2-20 % higher than those by the models trained with single institutional data (0.66-0.86).

CONCLUSION

The UNet performance, when trained with a single institutional dataset, exhibited similar accuracy to the model trained on a multi-institutional dataset. Segmentation accuracy increases with models trained on larger sample sizes, especially in more complex cyst segmentation.

Treatment for patients with autosomal dominant polycystic kidney disease in the chronic kidney disease without kidney replacement therapy in real-world clinical practice: a descriptive retrospective cohort study

BACKGROUND

In real-world clinical practice, treatments selected for patients with autosomal dominant polycystic kidney disease (ADPKD) in the chronic kidney disease (CKD) without kidney replacement therapy (KRT) have not been reported. This study investigated the oral treatments used in these patients and the changes in their use in recent years. Additionally, we studied the factors affecting tolvaptan dose reduction or discontinuation.

METHODS

This retrospective cohort study was conducted using the medical records of 160 hospitals in Japan. Patients with ADPKD or polycystic kidney disease registered on the database between January 2014 and December 2020 were selected. Changes in prescription proportions over time were assessed using the Cochran-Armitage test. We focused on patients prescribed with >15 mg of tolvaptan daily to identify the factors related to its dose reduction or discontinuation and used Multivariate Cox regression analysis to evaluate them.

RESULTS

Tolvaptan use in patients with ADPKD in the CKD without KRT stage has increased. As of 2020, 25% of patients were treated with tolvaptan. Overall, 3639 patients with ADPKD were enrolled in the database, of whom 156 were treated with tolvaptan. Of these, 64 patients (41%) reduced or discontinued tolvaptan during the observation period. The presence of an estimated glomerular filtration rate <60 mL/min/1.73 m2 at the beginning of the treatment was associated with a higher risk of tolvaptan dose reduction or discontinuation.

CONCLUSION

The proportion of patients with ADPKD treated with high-dose tolvaptan is increasing. However, patients with late-stage CKD tended to reduce or discontinue tolvaptan.

Activation of Polycystin-1 Signaling by Binding of Stalk-derived Peptide Agonists

Polycystin-1 (PC1) is the membrane protein product of the PKD1 gene whose mutation is responsible for 85% of the cases of autosomal dominant polycystic kidney disease (ADPKD). ADPKD is primarily characterized by the formation of renal cysts and potential kidney failure. PC1 is an atypical G protein-coupled receptor (GPCR) consisting of 11 transmembrane helices and an autocatalytic GAIN domain that cleaves PC1 into extracellular N-terminal (NTF) and membrane-embedded C-terminal (CTF) fragments. Recently, signaling activation of the PC1 CTF was shown to be regulated by a stalk tethered agonist (TA), a distinct mechanism observed in the adhesion GPCR family. A novel allosteric activation pathway was elucidated for the PC1 CTF through a combination of Gaussian accelerated molecular dynamics (GaMD), mutagenesis and cellular signaling experiments. Here, we show that synthetic, soluble peptides with 7 to 21 residues derived from the stalk TA, in particular, peptides including the first 9 residues (p9), 17 residues (p17) and 21 residues (p21) exhibited the ability to re-activate signaling by a stalkless PC1 CTF mutant in cellular assays. To reveal molecular mechanisms of stalk peptide-mediated signaling activation, we have applied a novel Peptide GaMD (Pep-GaMD) algorithm to elucidate binding conformations of selected stalk peptide agonists p9, p17 and p21 to the stalkless PC1 CTF. The simulations revealed multiple specific binding regions of the stalk peptide agonists to the PC1 protein including an "intermediate" bound yet inactive state. Our Pep-GaMD simulation findings were consistent with the cellular assay experimental data. Binding of peptide agonists to the TOP domain of PC1 induced close TOP-putative pore loop interactions, a characteristic feature of the PC1 CTF signaling activation mechanism. Using sequence covariation analysis of PC1 homologs, we further showed that the peptide binding regions were consistent with covarying residue pairs identified between the TOP domain and the stalk TA. Therefore, structural dynamic insights into the mechanisms of PC1 activation by stalk-derived peptide agonists have enabled an in-depth understanding of PC1 signaling. They will form a foundation for development of PC1 as a therapeutic target for the treatment of ADPKD.

Patient-Reported Outcomes Measures, Polycystic Kidney Disease Burden, and Outcomes in Autosomal Dominant Polycystic Kidney Disease

Rationale & Objective

Using OVERTURE (NCT01430494) study data on patient-perceived health, health care utilization, and productivity in autosomal dominant polycystic kidney disease (ADPKD), this research was conducted to characterize the burden of illness in patients with ADPKD and assess whether patient-reported outcome (PRO) assessment scores predict clinical and health-economic outcomes.

Study Design

Data were analyzed from a prospective, observational study.

Setting & Participants

The study cohort comprised 3,409 individuals with ADPKD in 20 countries who were aged 12-78 years and were in chronic kidney disease (CKD) stages G1-G5 and Mayo risk subclasses 1A-1E.

Predictors

Scores on PRO instruments, including disease-specific assessments [ADPKD-Impact Scale (ADPKD-IS), and ADPKD-Urinary Impact Scale (ADPKD-UIS)] and generic measures were assessed.

Outcomes

Clinical variables [eg, height-adjusted total kidney volume (htTKV), estimated glomerular filtration rate (eGFR), and abdominal girth] and health-economic outcomes were assessed.

Analytical Approach

Associations among variables were evaluated using Spearman correlations, logistic regression, and generalized linear mixed effects repeated measures models.

Results

Baseline CKD stage and Mayo risk classification showed little correlation with baseline PRO scores; however, scores on disease-specific instruments and measures of physical functioning were worse at more severe CKD stages. PRO scores predicted hospitalizations and sick days at 6-18 months, with strongest associations noted for the ADPKD-IS. PRO scores were not associated with htTKV and eGFR, but worse PRO scores were associated with greater abdominal girth. Poor baseline ADPKD-IS scores were positively associated with occurrence of ADPKD-related symptoms up to 18 months, including kidney pain (OR, 5.30; 95% CI, 2.75-10.24), hematuria (OR, 4.58; 95% CI, 1.99-10.53), and urinary tract infection (OR, 4.41; 95% CI, 1.93-10.11; P < 0.001 for all).

Limitations

A limitation of the study was the maximum 18 months of follow-up available to assess outcomes.

Conclusions

PRO scores predicted clinical and health-economic outcomes, such as hospitalization and absence from work, underscoring the importance of quality of life assessment of individuals with ADPKD.

Plain-Language Summary

Patient-reported outcomes (PROs) are increasingly recognized as important parameters for assessing the clinical and humanistic burden of autosomal dominant polycystic kidney disease (ADPKD). We analyzed data from the observational OVERTURE study to better characterize disease impact on quality of life and determine whether patient-perceived burden might predict outcomes. Scores on PRO assessment instruments predicted hospitalizations and sick days at 6-18 months, with associations strongest for the disease-specific ADPKD-Impact Scale. Compared to patients who rated their health-related quality of life as good, those with poor baseline scores were significantly more likely to report ADPKD-related signs and symptoms up to 18 months of follow-up. These findings support using disease-specific PRO assessment instruments to assess and predict the impact of ADPKD.

Clinical findings, underlying pathogenetic processes and treatment of vascular dysfunction in autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is an inherited disorder characterized by the development of fluid-filled cysts in the kidneys. The primary cause of ADPKD is mutations in the PKD1 (polycystic kidney disease 1) or PKD2 (polycystic kidney disease 2) gene. Patients with ADPKD often develop a variety of vascular abnormalities, which have a major impact on the structure and function of the blood vessels and can lead to complications such as hypertension, intracranial aneurysm (ICAN), and atherosclerosis. The progression of ADPKD involves intricate molecular and cellular processes that lead to the development of these vascular abnormalities. Our understanding of these processes remains incomplete, and available treatment options are limited. The aim of this review is to delve into the underlying mechanisms of these vascular abnormalities and to explore potential interventions.

Pedigree Analysis of Polycystic Kidney Disease Patients: Bangladeshi Perspective

Background

Polycystic kidney disease (PKD), an inheritance disorder which is the fourth leading cause of the end-stage renal disease. The inheritance pattern can be diagnosed and confirmed by pedigree analysis. The aim of the present research was to determine the type and frequency of PKD using pedigree analysis.

Materials and Methods

The present research was designed as a cross-sectional descriptive study. Thirty-eight adult Bangladeshi PKD patients were recruited using a selection checklist from the Department of Nephrology, Bangabandhu Sheikh Mujib Medical University, Dhaka, Bangladesh. Data were collected using a data collection sheet after taking informed written consent. The pedigree was drawn using the genetic pedigree chart creation software f-tree V4.0.6. The percentage frequencies of different types of pedigree were calculated using the Statistical Package for the Social Sciences software, version 23.

Results

A total of 24 (63.20%) had a positive family history and 36.80% (14) had no positive family history. All of the patients with a positive family history had vertical transmission; male and female were equally inheriting the gene. Out of these 24 patients, 4.17% (one), 8.33% (two), and 16.67% (four) had a homozygous/heterozygous state, skip generation, and male to male transmission, respectively.

Conclusions

Pedigree analysis of PKD patients showed an increased value in early diagnosis and better management and prognosis of the disease.

Effects of tolvaptan discontinuation in patients with autosomal dominant polycystic kidney disease: a post hoc pooled analysis

BACKGROUND

Tolvaptan slows kidney function decline in patients with autosomal dominant polycystic kidney disease (ADPKD) who are at risk of rapid progression. Given that treatment requires commitment to long-term use, we evaluated the effects of tolvaptan discontinuation on the trajectory of ADPKD progression.

METHODS

This was a post hoc analysis of pooled data from two clinical trials of tolvaptan (TEMPO 2:4 [NCT00413777] and TEMPO 3:4 [NCT00428948]), an extension trial (TEMPO 4:4 [NCT01214421]), and an observational study (OVERTURE [NCT01430494]) that enrolled patients from the other trials. Individual subject data were linked longitudinally across trials to construct analysis cohorts of subjects with a tolvaptan treatment duration > 180 days followed by an off-treatment observation period of > 180 days. For inclusion in Cohort 1, subjects were required have ≥ 2 outcome assessments during the tolvaptan treatment period and ≥ 2 assessments during the follow-up period. For Cohort 2, subjects were required to have ≥ 1 assessment during the tolvaptan treatment period and ≥ 1 assessment during the follow-up period. Outcomes were rates of change in estimated glomerular filtration rate (eGFR) and total kidney volume (TKV). Piecewise-mixed models compared changes in eGFR or TKV in the on-treatment and post-treatment periods.

RESULTS

In the Cohort 1 eGFR population (n = 20), the annual rate of eGFR change (in mL/min/1.73 m2) was -3.18 on treatment and -4.33 post-treatment, a difference that was not significant (P = 0.16), whereas in Cohort 2 (n = 82), the difference between on treatment (-1.89) and post-treatment (-4.94) was significant (P < 0.001). In the Cohort 1 TKV population (n = 11), TKV increased annually by 5.18% on treatment and 11.69% post-treatment (P = 0.06). In Cohort 2 (n = 88), the annual TKV growth rates were 5.15% on treatment and 8.16% post-treatment (P = 0.001).

CONCLUSIONS

Although limited by small sample sizes, these analyses showed directionally consistent acceleration in measures of ADPKD progression following the discontinuation of tolvaptan.

Tolvaptan and Kidney Function Decline in Older Individuals With Autosomal Dominant Polycystic Kidney Disease: A Pooled Analysis of Randomized Clinical Trials and Observational Studies

Rationale & Objective

Tolvaptan is indicated for treatment of patients with autosomal dominant polycystic kidney disease (ADPKD) at risk of rapid progression. Participants aged 56-65 years constituted a small proportion of the Replicating Evidence of Preserved Renal Function: an Investigation of Tolvaptan Safety and Efficacy in ADPKD (REPRISE) trial population. We assessed effects of tolvaptan on estimated glomerular filtration rate (eGFR) decline in participants aged >55 years.

Study Design

This was a pooled data analysis from 8 studies of tolvaptan or non-tolvaptan standard of care (SOC).

Setting & Participants

Participants aged >55 years with ADPKD were included. Data on participants in >1 study were linked longitudinally for maximum follow-up duration, with matching for age, sex, eGFR, and chronic kidney disease (CKD) stage to minimize confounding.

Interventions

Tolvaptan or non-tolvaptan SOC.

Outcomes

Treatment effects on annualized eGFR decline were compared using mixed models with fixed effects for treatment, time, treatment-by-time interaction, and baseline eGFR.

Results

In the pooled studies, 230 tolvaptan-treated and 907 SOC participants were aged >55 years at baseline. Ninety-five participant pairs from each treatment group were matched, all in CKD G3 or G4, ranging from 56.0 to 65.0 years (tolvaptan) or from 55.1 to 67.0 years (SOC). The eGFR annual decline rate was significantly reduced by 1.66 mL/min/1.73 m² (95% CI, 0.43-2.90; P = 0.009) in the tolvaptan group compared with SOC (-2.33 versus -3.99 mL/min/1.73 m²) over 3 years.

Limitations

Limitations include potential bias because of study population differences (bias risk was reduced through matching and multiple regression adjustment); vascular disease history data was not uniformly collected, and therefore not adjusted; and natural history of ADPKD precludes evaluating certain clinical endpoints within the study time frame.

Conclusions

In individuals aged 56-65 years with CKD G3 or G4, compared to a SOC group with mean GFR rate of decline ≥3 mL/min/1.73 m²/year, tolvaptan was associated with efficacy similar to that observed in the overall indication.

Funding

Otsuka Pharmaceutical Development & Commercialization, Inc (Rockville, MD).

Trial Registration

TEMPO 2:4 (NCT00413777); phase 1 tolvaptan trial (no NCT number; trial number 156-06-260); phase 2 tolvaptan trial (NCT01336972); TEMPO 4:4 (NCT01214421); REPRISE (NCT02160145); long-term tolvaptan safety extension trial (NCT02251275); OVERTURE (NCT01430494); HALT Progression of Polycystic Kidney Disease (HALT-PKD) study B (NCT01885559).

Clinical Pattern of Tolvaptan-Associated Liver Injury in Trial Participants With Autosomal Dominant Polycystic Kidney Disease (ADPKD): An Analysis of Pivotal Clinical Trials

RATIONALE & OBJECTIVE

Tolvaptan is associated with risk of drug-induced liver injury when used to treat autosomal dominant polycystic kidney disease (ADPKD). After this risk was described based on the clinical trials TEMPO 3:4 and TEMPO 4:4, additional data from the REPRISE trial and a long-term extension of TEMPO 4:4, REPRISE, and other tolvaptan trials in ADPKD have become available. To further characterize the hepatic safety profile of tolvaptan, an analysis of the expanded dataset was conducted.

STUDY DESIGN

Analysis of safety data from prospective clinical trials of tolvaptan.

SETTING & PARTICIPANTS

Multicenter clinical trials including more than 2,900 tolvaptan-treated participants, more than 2,300 with at least 18 months of drug exposure.

INTERVENTION

Tolvaptan administered twice daily in split-dose regimens.

OUTCOMES

Frequency of liver enzyme level increases detected by regular laboratory monitoring.

RESULTS

In the placebo-controlled REPRISE trial, more tolvaptan- than placebo-treated participants (38 of 681 [5.6%] vs 8 of 685 [1.2%]) experienced alanine aminotransferase level increases to >3× the upper limit of normal (ULN), similar to TEMPO 3:4 (40 of 957 [4.4%] vs 5 of 484 [1.0%]). No participant in REPRISE or the long-term extension experienced concurrent alanine aminotransferase level increases to >3× ULN and total bilirubin increases to >2× ULN ("Hy's Law" laboratory criteria). Based on the expanded dataset, liver enzyme increases most often occurred within 18 months after tolvaptan initiation and were less frequent thereafter. Increased levels returned to normal or near normal after treatment interruption or discontinuation. Thirty-eight patients were rechallenged with tolvaptan after the initial drug-induced liver injury episode, with return of liver enzyme level increases in 30; 1 additional participant showed a clinical "adaptation" after the initial episode, with resolution of the enzyme level increases despite continuation of tolvaptan.

LIMITATIONS

Retrospective analysis.

CONCLUSIONS

The absence of Hy's Law cases in REPRISE and the long-term extension trial support monthly liver enzyme monitoring during the first 18 months of tolvaptan exposure and every 3 months thereafter to detect and manage enzyme level increases, as is recommended on the drug label.

FUNDING

Otsuka Pharmaceutical Development & Commercialization, Inc.

TRIAL REGISTRATION

Trials included in the dataset were registered at ClinicalTrials.gov with study numbers NCT00428948 (TEMPO 3:4), NCT01214421 (TEMPO 4:4), NCT02160145 (REPRISE), and NCT02251275 (long-term extension).

Development of an enterocutaneous fistula from an intestinal perforation in a patient with autosomal dominant polycystic kidney disease

We herein report a case of enterocutaneous fistula in a patient with autosomal dominant polycystic kidney disease (ADPKD). A 37-year-old Japanese man was admitted to our hospital. Three months prior to transfer to our hospital, he developed intense flank pain with gross hematuria. His serum creatinine had decreased to 7.8 mg/dL and hemodialysis was started, but gross hematuria persisted and he developed hypotension. Upon admission, plain chest radiography did not reveal any free air, but computed tomography (CT) showed generalized ventral subcutaneous air from the head to the lower extremities and enlarged kidneys. Enterography showed leakage of contrast medium from the descending colon into the subcutaneous area. C-reactive protein was 23.1 mg/dL. A colostomy was placed in the transverse colon proximal to the perforation, and systemic subcutaneous drainage was performed. The fever subsequently resolved, and the C-reactive protein test became negative. Three months later, renal artery embolization was performed, and 12 months thereafter, CT showed a marked decrease in kidney size. We assume that a markedly enlarged kidney leaded to intestinal perforation, which developed into an enterocutaneous fistula. Consequently, intestinal fluid leaked into the subcutaneous cavity of the abdominal wall and spread systemically, resulting in extensive subcutaneous abscesses.

Venglustat, a Novel Glucosylceramide Synthase Inhibitor, in Patients at Risk of Rapidly Progressing ADPKD: Primary Results of a Double-Blind, Placebo-Controlled, Phase 2/3 Randomized Clinical Trial

RATIONALE & OBJECTIVE

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by the formation of multiple kidney cysts that leads to growth in total kidney volume (TKV) and progression to kidney failure. Venglustat is a glucosylceramide synthase inhibitor that has been shown to inhibit cyst growth and reduce kidney failure in preclinical models of ADPKD.

STUDY DESIGN

STAGED-PKD was a 2-stage, multicenter, double-blind, randomized, placebo-controlled phase 2/3 study in adults with ADPKD at risk of rapidly progressive disease, who were selected based on Mayo Clinic imaging classification of ADPKD class 1C, 1D, or 1E and an estimated glomerular filtration rate (eGFR) of 30-89.9mL/min/1.73m².

SETTING & PARTICIPANTS

Enrollment included 236 and 242 patients in stages 1 and 2, respectively.

INTERVENTIONS

In trial stage 1, the patients were randomized 1:1:1 to venglustat, 8mg; venglustat, 15mg; or placebo. In stage 2, the patients were randomized 1:1 to venglustat, 15mg (highest dose identified as safe and well tolerated in stage 1), or placebo.

OUTCOMES

Primary end points were rate of change in TKV over 18 months in stage 1 and eGFR slope over 24 months in stage 2. Secondary end points were eGFR slope over 18 months (stage 1), rate of change in TKV (stage 2), and safety/tolerability, pain, and fatigue (stages 1 and 2).

RESULTS

A prespecified interim futility analysis showed that venglustat treatment had no effect on the annualized rate of change in TKV over 18 months (stage 1) and had a faster rate of decline in eGFR slope over 24 months (stage 2). Due to this lack of efficacy, the study was terminated early.

LIMITATIONS

The short follow-up period after the end of treatment and limited generalizability of the findings.

CONCLUSIONS

In patients with rapidly progressing ADPKD, treatment with venglustat at either 8mg or 15mg showed no change in the rate of change in TKV and a faster rate of eGFR decline in STAGED-PKD despite a dose-dependent decrease in plasma glucosylceramide levels.

FUNDING

This study was funded by Sanofi.

TRIAL REGISTRATION

Registered at ClinicalTrials.gov with study number NCT03523728.

Caregiver Burden of Autosomal Dominant Polycystic Kidney Disease: A Qualitative Study

Rationale & Objective

There is limited published research on how autosomal dominant polycystic kidney disease (ADPKD) impacts caregivers. This study explored how caregivers of individuals with ADPKD perceive the burdens placed on them by the disease.

Study Design

Qualitative study consisting of focus groups and interviews. Discussions were conducted by trained interviewers using semi-structured interview guides.

Setting & Participants

The research was conducted in 14 countries in North America, South America, Asia, Australia, and Europe. Eligible participants were greater than or equal to 18 years old and caring for a child or adult diagnosed with ADPKD.

Analytical Approach

The concepts reported were coded using qualitative research software. Data saturation was reached when subsequent discussions introduced no new key concepts.

Results

Focus groups and interviews were held with 139 participants (mean age, 44.9 years; 66.9% female), including 25 participants who had a diagnosis of ADPKD themselves. Caregivers reported significant impact on their emotional (74.1%) and social life (38.1%), lost work productivity (26.6%), and reduced sleep (25.2%). Caregivers also reported worry about their financial situation (23.7%). In general, similar frequencies of impact were reported among caregivers with ADPKD versus caregivers without ADPKD, with the exception of sleep (8.0% vs 28.9%, respectively), leisure activities (28.0% vs 40.4% respectively), and work/employment (12.0% vs 29.8%, respectively).

Limitations

The study was observational and designed to elicit concepts, and only descriptive analyses were conducted.

Conclusions

These findings highlight the unique burden on caregivers in ADPKD, which results in substantial emotional, social, and professional/financial impact.

Glomerular hyperfiltration: part 2-clinical significance in children

Glomerular hyperfiltration (GHF) is a phenomenon that can occur in various clinical conditions affecting the kidneys such as sickle cell disease, diabetes mellitus, autosomal dominant polycystic kidney disease, and solitary functioning kidney. Yet, the pathophysiological mechanisms vary from one disease to another and are not well understood. More so, it has been demonstrated that GHF may occur at the single-nephron in some clinical conditions while in others at the whole-kidney level. In this review, we explore the pathophysiological mechanisms of GHF in relation to various clinical conditions in the pediatric population. In addition, we discuss the role and mechanism of action of important factors such as gender, low birth weight, and race in the pathogenesis of GHF. Finally, in this current review, we further highlight the consequences of GHF in the progression of kidney disease.

The wind of change in the management of autosomal dominant polycystic kidney disease in childhood

Significant progress has been made in understanding the genetic basis of autosomal dominant polycystic kidney disease (ADPKD), quantifying disease manifestations in children, exploring very-early onset ADPKD as well as pharmacological delay of disease progression in adults. At least 20% of children with ADPKD have relevant, yet mainly asymptomatic disease manifestations such as hypertension or proteinuria (in line with findings in adults with ADPKD, where hypertension and cardiovascular damage precede decline in kidney function). We propose an algorithm for work-up and management based on current recommendations that integrates the need to screen regularly for hypertension and proteinuria in offspring of affected parents with different options regarding diagnostic testing, which need to be discussed with the family with regard to ethical and practical aspects. Indications and scope of genetic testing are discussed. Pharmacological management includes renin-angiotensin system blockade as first-line therapy for hypertension and proteinuria. The vasopressin receptor antagonist tolvaptan is licensed for delaying disease progression in adults with ADPKD who are likely to experience kidney failure. A clinical trial in children is currently ongoing; however, valid prediction models to identify children likely to suffer kidney failure are lacking. Non-pharmacological interventions in this population also deserve further study.

The Effect of Smoking on Endothelial Dysfunction in Autosomal Dominant Polycystic Kidney Disease Patients with Preserved Renal Function

Background

In autosomal dominant polycystic kidney disease (ADPKD), endothelial dysfunction (ED) is common and occurs much earlier than kidney function impairment. The impact of smoking on ED in ADPKD patients has not been previously studied. The aim of this study was to investigate the potential contribution of smoking habits to ED and subclinical atherosclerosis in these patients.

Methods

This case-control study included 54 ADPKD patients with preserved renal function and 45 healthy control subjects. ED was assessed using ischemia-induced forearm flow-mediated dilatation (FMD). Carotid intima-media thickness (CIMT) was measured from 10 mm proximal to the right common carotid artery. Clinical demographic characteristics and laboratory data were recorded for the patients and control group. Regression analysis was used to determine independent associations of ED and CIMT.

Results

FMD was significantly lower in the ADPKD patients (19.5 ± 5.63 vs. 16.56 ± 6.41, p = .018). Compared with nonsmoker ADPKD patients, smoker patients had significantly lower FMD values (18.19 ± 6.52 vs. 13.79 ± 5.27, p = .013). In multiple regression analysis, age (β = –0.294, 95% CI: −0.392: −1.96, p = .001) for FMD and smoking (β  =  1.328, 95% CI: 0.251, 2.404, p = .017) for CIMT were independent predictors.

Conclusions

Patients with ADPKD had more impaired endothelial function and subclinical atherosclerosis compared with control subjects. Smoking may increase the risk of subclinical atherosclerosis in ADPKD patients.

PKD1-Associated Arachnoid Cysts in Autosomal Dominant Polycystic Kidney Disease

OBJECTIVES

the prevalence of intracranial aneurysms and arachnoid cysts is higher in patients with autosomal dominant polycystic kidney disease (ADPKD) than in the general population. A genotype correlation was reported for intracranial aneurysms, but it is unclear for arachnoid cysts. Therefore, the genotype correlation with intracranial aneurysms and arachnoid cysts was investigated in ADPKD.

MATERIALS AND METHODS

intracranial aneurysms and arachnoid cysts were screened by magnetic resonance imaging (MRI), and PKD genotypes were examined using next-generation sequencing for 169 patients with ADPKD.

RESULTS

PKD1-, PKD2- and no-mutation were identified in 137, 24 and 8 patients, respectively. Intracranial aneurysms and arachnoid cysts were found in 34 and 25 patients, respectively, with no significant difference in frequency. Genotype, sex, estimated glomerular filtration rate and age at ADPKD diagnosis significantly affected the age at brain MRI. The proportional hazard risk analyzed using the age at brain MRI adjusted by these four variables was 5.0-times higher in the PKD1 group than in the PKD2 group for arachnoid cysts (P = 0.0357), but it was not different for intracranial aneurysms (P = 0.1605). Arachnoid cysts were diagnosed earlier in the PKD1 group than in the PKD2 group (54.8 vs 67.7 years, P = 0.0231), but no difference was found for intracranial aneurysms (P = 0.4738) by Kaplan-Meier analysis.

CONCLUSIONS

this study demonstrated the correlation between arachnoid cysts and PKD1 mutation. The reported association of arachnoid cysts with advanced renal disease may be due to the common correlation of these factors with PKD1 mutation.

A case of autosomal dominant polycystic kidney disease with amelioration of refractory cyst infections following prolonged hemodialysis time

Renal cyst infection is a frequent and serious problem in patients with autosomal dominant polycystic kidney disease (ADPKD). Cyst infection is often a refractory complication of treatment that leads to sepsis and death in patients with ADPKD. It was previously reported that a higher dose of dialysis demonstrated clearly better survival than shorten-time dialysis. The relationship between the frequency of cyst infection episodes in hemodialysis (HD) patients with ADPKD and the dialysis dose has not yet been fully elucidated. In this report, we describe a case of an HD patient with ADPKD that was provided elongation of HD time from 4-h twice weekly HD to 8-h thrice weekly nocturnal HD. As a result, the frequency of cyst infection episodes decreased from 10.0 to 1.5 days a month. Our findings suggest that prolonged HD time might contribute to amelioration of refractory cyst infections in patients with ADPKD.

Effect of tolvaptan in Japanese patients with autosomal dominant polycystic kidney disease: a post hoc analysis of TEMPO 3:4 and TEMPO Extension Japan

Background

Autosomal dominant polycystic kidney disease (ADPKD) is a progressive condition that eventually leads to end-stage renal disease. A phase 3 trial of tolvaptan (TEMPO 3:4; NCT00428948) and its open-label extension (TEMPO Extension Japan: TEMPO-EXTJ; NCT01280721) were conducted in patients with ADPKD. In this post hoc analysis, effects on renal function and the safety profile of tolvaptan were assessed over a long-term period that included the 3-year TEMPO 3:4 and the approximately 3-year TEMPO-EXTJ trials.

Methods

Patients from Japanese trial sites who completed TEMPO 3:4 were offered participation in TEMPO-EXTJ. Patients whose efficacy parameters were measured at year 2 in TEMPO-EXTJ for efficacy evaluation were included. The annual slope of the estimated glomerular filtration rate (eGFR) and growth in total kidney volume (TKV) were analyzed.

Results

In patients who received tolvaptan in TEMPO 3:4 and TEMPO-EXTJ, the annual slope of eGFR (mL/min/1.73 m²) was − 3.480 in TEMPO 3:4 and − 3.417 in TEMPO-EXTJ, with no apparent effect of an approximately 3.6-month off-treatment interval between the two trials. In patients who received a placebo in TEMPO 3:4 before initiating tolvaptan in TEMPO-EXTJ, the slope of eGFR was significantly less steep from TEMPO 3:4 (− 4.287) to TEMPO-EXTJ (− 3.364), a difference of 0.923 (P = 0.0441).

Conclusion

The TEMPO-EXTJ trial supports a sustained beneficial effect of tolvaptan on eGFR. In patients who received a placebo in TEMPO 3:4, initiation of tolvaptan in TEMPO-EXTJ was associated with a significant slowing of eGFR decline.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10157-021-02083-y.

The correlation between kidney volume and measured glomerular filtration rate in an Asian ADPKD population: a prospective cohort study

Background

Autosomal dominant polycystic kidney disease (ADPKD) is the most common hereditary kidney disorder that leads to end stage renal disease (ESRD). Cyst expansion in ADPKD is strongly associated with the decline in renal function. However, the correlation between total kidney volume (TKV) and glomerular filtration rate (GFR) at an early stage has not been well demonstrated. There is growing evidence that utilization of estimated GFR (eGFR) may induce misleading information in a population with near normal renal function. Therefore, a more accurate method is essential.

Methods

A prospective cohort of ADPKD patients was conducted with clinical data and laboratory collection. Measured GFR (mGFR) was assessed by iohexol plasma clearance method using ultra performance liquid chromatography. eGFR was calculated using the CKD-EPI equation. Kidney volumes were evaluated using MRI imaging protocol.

Results

Thirty two patients completed the study. The mean age was 56 years old. The mean initial mGFR was 83.8 mL/min/1.73m². The mean change in mGFR per year was –2.99 mL/min/1.73m²/year. The mean initial height-adjusted TKV (htTKV) was 681.0 mL/m. The mean percentage change in htTKV per year (%ΔhtTKV/y) was 4.77 %/year. mGFR had a better association with clinical parameters than eGFR. Initial mGFR was significantly and inversely correlated with initial htTKV and age. The percentage change in mGFR per year was significantly and inversely correlated with the %ΔhtTKV/y and 24-hr urine albumin. The %ΔhtTKV/y was significantly correlated with initial htTKV.

Conclusions

Our studies demonstrated that mGFR using iohexol is a more reliable and accurate method than eGFR for evaluating GFR changes in the early stages of ADPKD patients. There is a strong inverse correlation between kidney volume and mGFR in an Asian ADPKD population. The initial htTKV is a good predictor of kidney volume progression. The %ΔhtTKV/y is a good early surrogate marker for the decline in renal function. 24-hr urine albumin is also a good indicator for renal progression.

Overexpression of DJ-1 alleviates autosomal dominant polycystic kidney disease by regulating cell proliferation, apoptosis, and mitochondrial metabolism in vitro and in vivo

Background

DJ-1 is critical for the mitochondrial function associated with autosomal dominant polycystic kidney disease (ADPKD). We aimed to investigate DJ-1’s function in the pathogenesis of ADPKD.

Methods

DJ-1 was knocked-down in IMCD3 cells to evaluate the effects of DJ-1 on cell phenotype and mitochondrial function in vitro. Furthermore, we generated three groups of mice with different expression levels of DJ-1 within an established ADPKD model: ADPKD, ADPKD^pcDNA, and ADPKD^pcDNA-DJ-1.

Results

DJ-1 knock-down significantly increased oxidative stress as well as the proliferation and apoptosis rate of IMCD3 cells, along with Bcl-2 down-regulation and the up-regulation of Ki67, PCNA, Bax, cleaved caspase-3, and cleaved caspase-9. DJ-1 knock-down suppressed the cellular respiration, Ca²⁺ absorption, and mitochondrial complex I activity in mitochondria. In vivo, we verified that DJ-1 was down-regulated in ADPKD models, and its overexpression attenuated the renal dysfunction in ADPKD models. The transgenic mice had a significantly smaller renal cyst and less interstitial fibrosis than control, accompanied byα-SMA, fibronectin, and TGF-β1 up-regulation. Moreover, in vivo results confirmed DJ-1 overexpression inhibited the proliferation and apoptosis of tubular epithelial cells along with down-regulation of Ki67, PCNA, p53, intracellular Cyt c, cleaved caspase-3, and cleaved caspase-9 and the up-regulation of Bcl-2.

Conclusions

DJ-1 was down-regulated in ADPKD models, and its overexpression may attenuate the renal dysfunction and pathological damage by regulating the proliferation, apoptosis, oxidative stress and mitochondrial metabolism, which may be mediated by the p53 signaling pathway.

Combined Preimplantation Genetic Testing for Autosomal Dominant Polycystic Kidney Disease: Consequences for Embryos Available for Transfer

Autosomal dominant polycystic kidney disease (ADPKD) is the most common hereditary kidney disease and presents with genetic and clinical heterogeneity. ADPKD can also manifest extra-renally, and seminal cysts have been associated with male infertility in some cases. ADPKD-linked male infertility, along with female age, have been proposed as factors that may influence the clinical outcomes of preimplantation genetic testing (PGT) for monogenic disorders (PGT-M). Large PGT for aneuploidy assessment (PGT-A) studies link embryo aneuploidy to increasing female age; other studies suggest that embryo aneuploidy is also linked to severe male-factor infertility. We aimed to assess the number of aneuploid embryos and the number of cycles with transferable embryos in ADPKD patients after combined-PGT. The combined-PGT protocol, involving PGT-M by PCR and PGT-A by next-generation sequencing, was performed in single trophectoderm biopsies from 289 embryos in 83 PGT cycles. Transferable embryos were obtained in 69.9% of cycles. The number of aneuploid embryos and cycles with transferable embryos did not differ when the male or female had the ADPKD mutation. However, a significantly higher proportion of aneuploid embryos was found in the advanced maternal age (AMA) group, but not in the male factor (MF) group, when compared to non-AMA and non-MF groups, respectively. Additionally, no significant differences in the percentage of cycles with transferable embryos were found in any of the groups. Our results indicate that AMA couples among ADPKD patients have an increased risk of aneuploid embryos, but ADPKD-linked male infertility does not promote an increased aneuploidy rate.

Implications of the PAPP-A-IGFBP-IGF-1 pathway in the pathogenesis and treatment of polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is one of the most common genetic diseases implicated in the development of end stage renal disease (ESRD). Although FDA has recently approved a drug against ADPKD, there is still a great need for development of alternative management strategies for ADPKD. Understanding the different mechanisms that lead to cystogenesis and cyst expansion in ADPKD is imperative to develop new therapies against ADPKD. Recently, we demonstrated that caloric restriction can prevent the development of cystic disease in animal models of ADPKD and through these studies identified a new role for pregnancy associated plasma protein-A (PAPP-A), a component of the insulin-like growth factors (IGF) pathway, in the pathogenesis of this disease. The PAPP-A-IGF pathway plays an important role in regulation of cell growth, differentiation, and transformation and dysregulation of this pathway has been implicated in many diseases. Several indirect studies support the involvement of IGF-1 in the pathogenesis of ADPKD. However, it was only recently that we described a direct role for a component of this pathway in pathogenesis of ADPKD, opening a new avenue for the therapeutic approaches for this cystic disease. The present literature review will critically discuss the evidence that supports the role of components of IGF pathway in the pathogenesis of ADPKD and discuss the pharmacological implications of PAPP-A-IGF axis in this disease.

Core Outcome Domains for Trials in Autosomal Dominant Polycystic Kidney Disease: An International Delphi Survey

RATIONALE & OBJECTIVE

Outcomes reported in trials involving patients with autosomal dominant polycystic kidney disease (ADPKD) are heterogeneous and rarely include patient-reported outcomes. We aimed to identify critically important consensus-based core outcome domains to be reported in trials in ADPKD.

STUDY DESIGN

An international 2-round online Delphi survey was conducted in English, French, and Korean languages.

SETTING & PARTICIPANTS

Patients/caregivers and health professionals completed a 9-point Likert scale (7-9 indicating critical importance) and a Best-Worst Scale.

ANALYTICAL APPROACH

The absolute and relative importance of outcomes were assessed. Comments were analyzed thematically.

RESULTS

1,014 participants (603 [60%] patients/caregivers, 411 [40%] health professionals) from 56 countries completed round 1, and 713 (70%) completed round 2. The prioritized outcomes were kidney function (importance score, 8.6), end-stage kidney disease (8.6), death (7.9), blood pressure (7.9), kidney cyst size/growth (7.8), and cerebral aneurysm (7.7). Kidney cyst-related pain was the highest rated patient-reported outcome by both stakeholder groups. Seven themes explained the prioritization of outcomes: protecting life and health, directly encountering life-threatening and debilitating consequences, specificity to ADPKD, optimizing and extending quality of life, hidden suffering, destroying self-confidence, and lost opportunities.

LIMITATIONS

Study design precluded involvement from those without access to internet or limited computer literacy.

CONCLUSIONS

Kidney function, end-stage kidney disease, and death were the most important outcomes to patients, caregivers, and health professionals. Kidney cyst-related pain was the highest rated patient-reported outcome. Consistent reporting of these top prioritized outcomes may strengthen the value of trials in ADPKD for decision making.

Range and Variability of Outcomes Reported in Randomized Trials Conducted in Patients With Polycystic Kidney Disease: A Systematic Review

RATIONALE & OBJECTIVE

Trials in autosomal dominant polycystic kidney disease (ADPKD) have increased, but their impact on decision making has been limited. Because heterogeneity in reported outcomes may be responsible, we assessed their range and variability in ADPKD trials.

STUDY DESIGN

Systematic review.

SETTING & STUDY POPULATION

Adult participants in clinical trials in ADPKD.

SELECTION CRITERIA FOR STUDIES

We included trials that studied adults and were published in English. For trials that enrolled patients without ADPKD, only those enrolling ≥50% of participants with ADPKD were included.

DATA EXTRACTION

We extracted information on all discrete outcome measures, grouped them into 97 domains, and classified them into clinical, surrogate, and patient-reported categories. For each category, we choose the 3 most frequently reported domains and performed a detailed analysis of outcome measures.

ANALYTICAL APPROACH

Frequencies and characteristics of outcome measures were described.

RESULTS

Among 68 trials, 1,413 different outcome measures were reported. 97 domains were identified; 41 (42%) were surrogate, 30 (31%) were clinical, and 26 (27%) were patient reported. The 3 most frequently reported domains were in the surrogate category: kidney function (54; 79% of trials; using 46 measures), kidney and cyst volumes (43; 63% of trials; 52 measures), and blood pressure (27; 40% of trials, 30 measures); in the clinical category: infection (10; 15%; 21 measures), cardiovascular events (9; 13%; 6 measures), and kidney failure requiring kidney replacement therapy (8; 12%; 5 measures); and in the patient-reported category: pain related to ADPKD (16; 24%; 26 measures), pain for other reasons (11; 16%; 11 measures), and diarrhea/constipation/gas (10; 15%; 9 measures).

LIMITATIONS

Outcome measures were assessed for only the top 3 domains in each category.

CONCLUSIONS

The outcomes in ADPKD trials are broad in scope and highly variable. Surrogate outcomes were most frequently reported. Patient-reported outcomes were uncommon. A consensus-based set of core outcomes meaningful to patients and clinicians is needed for future ADPKD trials.

Spontaneous coronary artery dissection in a patient with hereditary polycystic kidney disease and a recent liver transplant: a case report

Background

Spontaneous coronary artery dissection (SCAD) is an underestimated cause of acute coronary syndromes. A predisposing arteriopathy is often present and a stressor can sometimes be identified. Autosomal dominant polycystic kidney disease (ADPKD) is the most common hereditary kidney disorder; its associated arteriopathy has been described as a predisposing condition for SCAD.

Case summary

A 44-year-old woman with ADPKD presented in the emergency room with recent onset thoracic pain radiating to the left arm at rest. She had undergone a recent liver transplant, for which she had received high-dose corticosteroids during 1 month. She was still taking tacrolimus and mycophenolate mofetil. She had no traditional risk factors but had experienced stress postoperatively. She was known with moderate chronic kidney disease. The initial electrocardiogram (ECG) was normal but high-sensitive troponin T was significantly elevated. Coronary angiography demonstrated diffuse narrowing of the distal left anterior descending artery with preserved flow, compatible with a SCAD Type 2 that was treated conservatively. However, under dual antiplatelet therapy (DAPT) with clopidogrel, the coronary dissection was progressive with new ischaemic ECG changes, further rise of troponins and development of apicoseptal hypokinesia. Because of the small vessel diameter and the preserved distal flow, conservative treatment was maintained. Clopidogrel was interrupted and the patient remained stable.

Discussion

As SCAD remains an underestimated cause of myocardial infarction, clinicians should be aware of the possibility of SCAD in ADPKD patients with chest pain. This case report illustrates that the decision DAPT vs. aspirin should be individualized in these patients.

Co-inheritance of pathogenic variants in PKD1 and PKD2 genes presenting as severe antenatal phenotype of autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is caused by pathogenic variants in either PKD1 or PKD2 genes. Disease severity is dependent on various factors including the presence of modifier genes. We describe a family with recurrent foetal presentation of ADPKD due to co-inheritance of pathogenic variants in both PKD1 [c.3860T > C; p.(Leu1287Pro)] and PKD2 [(c.1000C > A; p.(Pro334Thr)] genes. Familial segregation studies revealed the mother and the father to be heterozygous for the same variants in the PKD1 and PKD2 genes, respectively, as found in the foetus. Renal ultrasonography detected evidence of cystic disease in the mother and two of her family members. No cysts were detected in the father, however the paternal grandfather died of renal cystic disease. The absence of disease in the father can be explained by the phenomenon of incomplete penetrance, or Knudson's two-hit hypothesis of cystogenesis in the grandfather. This case underscores the importance of sequencing PKD2 gene even in the presence of a familial PKD1 variant, as well as genetic testing of the cysts for evidence of the second hit.

Cyclooxygenase 2 inhibition slows disease progression and improves the altered renal lipid mediator profile in the Pkd2WS25/- mouse model of autosomal dominant polycystic kidney disease

BACKGROUND

Increased levels of cyclooxygenase (COX) derived oxylipins is the earliest and most consistent alteration in the renal oxylipin profile in diverse models of cystic kidney diseases. Therefore, we examined whether a COX2 inhibitor would reduce disease progression in the Pkd2WS25/- mouse model of autosomal dominant polycystic kidney disease (ADPKD).

METHODS

Weanling normal and diseased male Pkd2 mice were provided diets that provided 0 or 50 mg celecoxib/kg body weight/day, for 13 weeks. Renal disease and function were assessed by histomorphometric analysis of renal cysts and measurement of serum creatinine and urea nitrogen (SUN) levels. Targeted lipidomic analysis of renal oxylipins was performed by HPLC-MS/MS.

RESULTS

Diseased mice had significant cyst involvement and reduced renal function as indicated by elevated serum creatinine and SUN. Celecoxib reduced cyst area by 48%, cyst volume by 70%, and serum creatinine and SUN by 20% and 16%, respectively. Consistent with our previous studies, 8 of the 11 COX derived oxylipins were higher in diseased kidneys. In addition, 24 of 33 lipoxygenase (LOX) derived oxylipins and 7 of 16 cytochrome P450 (CYP) derived oxylipins were lower in diseased kidneys. Celecoxib reduced total and five of the eight individual elevated COX oxylipins and increased 5 of 24 LOX and 5 of 7 CYP oxylipins that were reduced by disease.

CONCLUSIONS

COX2 inhibition ameliorates disease progression, improves renal function and improves the altered oxylipins in Pkd2 mice. This represents a potential new approach for treatment of ADPKD, a disorder for which no effective treatment currently exists.

Mineralocorticoid Antagonism and Vascular Function in Early Autosomal Dominant Polycystic Kidney Disease: A Randomized Controlled Trial

RATIONALE & OBJECTIVE

Vascular dysfunction, characterized by impaired vascular endothelial function and increased large-elastic artery stiffness, is evident early in autosomal dominant polycystic kidney disease (ADPKD) and is an important predictor of cardiovascular events and mortality. Aldosterone excess has been implicated in the development of endothelial dysfunction and arterial stiffness, in part by causing increased oxidative stress and inflammation. We hypothesized that aldosterone antagonism would reduce vascular dysfunction in patients with early-stage ADPKD.

STUDY DESIGN

Prospective, randomized, controlled, double-blind, clinical trial.

SETTING & PARTICIPANTS

61 adults aged 20 to 55 years with ADPKD, estimated glomerular filtration rate ≥ 60mL/min/1.73m², and receiving a renin-angiotensin-aldosterone system inhibitor.

INTERVENTION

Spironolactone (maximum dose, 50mg/d) or placebo for 24 weeks.

OUTCOMES

Change in brachial artery flow-mediated dilation (FMD_BA) was the primary end point and change in carotid-femoral pulse-wave velocity (CFPWV) was the secondary end point.

RESULTS

60 participants completed the trial. Participants had a mean age of 34±10 (SD) years, 54% were women, and 84% were non-Hispanic white. Spironolactone did not change FMD_BA (8.0% ± 5.5% and 7.8% ± 4.3% at baseline and 24 weeks, respectively, vs corresponding values in the placebo group of 8.4% ± 6.2% and 8.0% ± 4.6%; P=0.9for comparison of change between groups) or CFPWV (640±127 and 603±101cm/s at baseline and 24 weeks, respectively, vs corresponding values in the placebo group of 659±138 and 658±131cm/s; P=0.1). Brachial systolic blood pressure was reduced with spironolactone (median change, -6 [IQR, -15, 1] vs -2 [IQR, -7, 10] mm Hg in the placebo group; P=0.04). Spironolactone did not change the majority of circulating and/or endothelial cell markers of oxidative stress/inflammation and did not change vascular oxidative stress.

LIMITATIONS

Low level of baseline vascular dysfunction; lack of aldosterone measurements.

CONCLUSIONS

24 weeks of aldosterone antagonism reduced systolic blood pressure without changing vascular function in patients with early-stage ADPKD.

FUNDING

NIDDK, NIH National Center for Advancing Translational Sciences, and the Zell Family Foundation.

TRIAL REGISTRATION

Registered at ClinicalTrials.gov with study number NCT01853553.

Revisiting racial differences in ESRD due to ADPKD in the United States

Introduction

Autosomal dominant polycystic kidney disease (ADPKD) affects all races. Whether the progression of ADPKD varies by race remains unclear.

Methods

In this retrospective cohort study from 2004 to 2013 non-Hispanic blacks and non-Hispanic whites of all ages classified in the US Renal Data System (USRDS) with incident ESRD from ADPKD (n = 23,647), hypertension/large vessel disease (n = 296,352), or diabetes mellitus (n = 451,760) were stratified into five-year age categories ranging from < 40 to > 75 (e.g., < 40, 40–44, 45–49, …, 75+). The Cochran-Mantel-Haenszel test was used to determine the association of race and incidence of ESRD from ADPKD, diabetes, or hypertension. The difference in the proportions of ESRD in non-Hispanic black and non-Hispanic white patients at each age categorical bin was compared by two-sample proportion test. The age of ESRD onset between non-Hispanic black and non-Hispanic white patients at each year was compared using two-sample t-test with unequal variance.

Results

1.068% of non-Hispanic blacks and 2.778% of non-Hispanic whites had ESRD attributed to ADPKD. Non-Hispanic blacks were less likely than non-Hispanic whites to have ESRD attributed to ADPKD (odds ratio (OR) (95% CI) = 0.38 (0.36–0.39), p <  0.0001). Using US Census data as the denominator to adjust for population differences non-Hispanic blacks were still slightly under-represented (OR (95% CI) 0.94 (0.91–0.96), p = 0.004). However, non-Hispanic blacks with ADPKD had a younger age of ESRD (54.4 years ±13) than non-Hispanic whites (55.9 years ±12.8) (p <  0.0001). For those < 40 years old, more non-Hispanic blacks had incident ESRD from ADPKD than non-Hispanic whites (9.49% vs. 7.68%, difference (95% CI) = 1.81% (0.87–2.84%), p <  0.001) for the combined years examined.

Conclusions

As previously shown, we find the incidence of ESRD from ADPKD in non-Hispanic blacks is lower than in non-Hispanic whites. Among the younger ADPKD population (age < 40), however, more non-Hispanic blacks initiated dialysis than non-Hispanic whites. Non-Hispanic blacks with ADPKD initiated dialysis younger than non-Hispanic whites. A potential implication of these findings may be that black race should be considered an additional risk factor for progression in ADPKD.

Clinical Manifestation, Management and Prognosis of Acute Myocardial Infarction in Autosomal Dominant Polycystic Kidney Disease

BACKGROUND/AIMS

Cardiovascular complications are the most common cause of death in individuals with autosomal dominant polycystic kidney disease (ADPKD), yet there is no substantial data concerning the clinical characteristics of acute myocardial infarction (AMI) in this population. This study thus aimed to investigate AMI in persons with ADPKD.

METHODS

A retrospective analysis of ADPKD patients admitted to our hospital over a 13 year period was conducted. Age and gender-matched control patients without ADPKD were also selected at a ratio of 1: 10.

RESULTS

A total of 52 ADPKD and 520 non-ADPKD patients were enrolled in the present study, with those in the former group exhibiting significantly poorer kidney function. The distribution of AMI types differed significantly between these two groups. The incidence of ST-segment elevation myocardial infarction (STEMI) was higher (75.0%) and the incidence of non-ST segment elevation myocardial infarction (NSTEMI) was lower (25.0%) in the ADPKD group. At the onset of AMI, sudden cardiac death (SCD) was more common in ADPKD patients (11.5% vs. 4.6%). In terms of risk factors, the occurrence of hypertension was greater in ADPKD patients (78.8% vs. 39.6%). With regard to subsequent management, ADPKD patients had a higher prevalence of triple-branch coronary lesions (21.1% vs. 11.2%), undergoing more coronary artery bypass grafting (CABG) (7.7% vs. 5.4%) and fewer percutaneous coronary interventions (PCI) (73.1% vs. 84.6%). Overall, ADPKD patients had higher rates of mortality (13.5% vs. 6.2%).

CONCLUSION

ADPKD patients with AMI suffer from more severe conditions and difficult therapies, resulting in a poorer prognosis.

Age- and height-adjusted total kidney volume growth rate in autosomal dominant polycystic kidney diseases

Background

The Mayo Clinic Image Classification (MIC) was proposed as a renal prognosis prediction model for autosomal dominant polycystic kidney disease (ADPKD). MIC is based on the assumption of exponential constant increase in height-adjusted total kidney volume (HtTKV). HtTKV growth rate is calculated by one-time measurement of HtTKV and age. We named it as an age-adjusted HtTKV growth rate (AHTKV-α). AHTKV-α was compared with HtTKV slope measured by at least two HtTKV values.

Methods

Comparison of repeatability between AHTKV-α and HtTKV slope, correlation of subgroups divided according to baseline AHTKV-α and HtTKV slope with disease manifestations, estimated glomerular filtration rate (eGFR) slope, and renal survival were analyzed in 296 patients with ADPKD. PKD genotype influences were compared between AHTKV-α and HtTKV slope in 88 patients with characterized PKD mutations.

Results

Absolute differences between baseline and follow-up measures were significantly larger for the HtTKV slope than for AHTKV-α (P < 0.0001). From baseline AHTKV-α-based subgroups A–E according to MIC, disease manifestations occurred earlier and future eGFR slopes became steeper (P < 0.0001). Multivariate hazard ratios of renal survival differed significantly among baseline AHTKV-α-based subgroups. Inter-subgroup differences in these predictors were less evident during baseline HtTKV slope-based classification. AHTKV-α values, but not HtTKV slopes, were significantly higher for PKD1 mutation carriers than for PKD2 mutation carriers (P < 0.0001).

Conclusion

MIC is a good renal prediction model applicable to Japanese patients also. AHTKV-α can be a more sensitive and reliable indicator in TKV growth rate than HtTKV slope.

Electronic supplementary material

The online version of this article (10.1007/s10157-018-1617-8) contains supplementary material, which is available to authorized users.

Esophageal Artery Pseudoaneurysm and Takayasu Arteritis in a Patient with Autosomal Dominant Polycystic Kidney Disease

A 47-year-old female previously diagnosed with ADPKD visited the hospital due to sudden pain in her upper abdomen and back. Esophagogastroduodenoscopy, contrast-enhanced abdominal computed tomography (CT), and CT angiography identified an esophageal artery pseudoaneurysm and hematoma in the esophagus. Urgent angiography and embolization were performed. After the procedure, CT angiography and positron emission tomography were performed due to differences in blood pressure between the arms. The patient was also found to have Takayasu arteritis and subsequently received outpatient follow-up care. The possible mechanisms that cause vascular abnormalities in ADPKD patients include damaged vascular integrity due to abnormal polycystin expression caused by PKD mutations and connective tissue abnormalities. Further research is needed to confirm these mechanisms, and ADPKD patients should be assessed for vascular abnormalities.

Optimal equation for estimation of glomerular filtration rate in autosomal dominant polycystic kidney disease: influence of tolvaptan

BACKGROUND

The reliability of various equations for estimating the GFR in ADPKD patients and the influence of tolvaptan on the resulting estimates have not been examined when GFR is calculated on the basis of inulin clearance.

METHODS

We obtained baseline and on-tolvaptan measured GFRs (mGFRs), calculated on the basis of inulin clearance, in 114 ADPKD, and these mGFRs were compared with eGFRs calculated according to four basic equations: the MDRD, CKD-EPI, and JSN-CKDI equations and the Cockcroft-Gault formula, as well as the influence of tolvaptan and of inclusion of cystatin C on accuracy of the results. Accuracy of each of the seven total equations was evaluated on the basis of the percentage of eGFR values within mGFR ± 30% (P₃₀).

RESULTS

mGFRs were distributed throughout CKD stages 1-5. Regardless of the CKD stage, P₃₀s of the MDRD, CKD-EPI, and JSN-CKDI equations did not differ significantly between baseline values and on-tolvaptan values. In CKD 1-2 patients, P₃₀ of the CKD-EPI equation was 100.0%, whether or not the patient was on-tolvaptan. In CKD 3-5 patients, P₃₀s of the MDRD, CKD-EPI, and JSN-CKDI equations were similar. For all four equations, regression coefficients and intercepts did not differ significantly between baseline and on-tolvaptan values, but accuracy of the Cockcroft-Gault formula was inferior to that of the other three equations. Incorporation of serum cystatin C reduced accuracy.

CONCLUSIONS

The CKD-EPI equation is most reliable, regardless of the severity of CKD. Tolvaptain intake has minimal influence and cystatin C incorporation does not improve accuracy.

Autosomal dominant polycystic kidney disease: a potential mistake in the interpretation of radioiodine whole-body scintigraphy

There are a few case reports of renal cysts demonstrating radioiodine uptake on scintigraphy. In this case, we report a 49-year-old man who had undergone total thyroidectomy and had been treated with radioiodine. After conventional levothyroxine withdrawal, the patient underwent thyroid remnant ablation by oral administration of 125 mci ¹³¹I. Seven days later, post-therapy whole-body scan demonstrated thyroid remnant tissue and bilaterally multifocal radioiodine uptake in the upper abdomen. By ultrasonography and abdominal computed tomography scan, the iodine uptake was proven to be due to the accumulation of ¹³¹I in bilateral polycystic kidney disease.

Preimplantation Genetic Diagnosis Counseling in Autosomal Dominant Polycystic Kidney Disease

Autosomal dominant polycystic kidney disease (ADPKD) is one of the most common hereditary forms of chronic kidney disease. Mutations within PKD1 or PKD2 lead to innumerable fluid-filled cysts in the kidneys and in some instances, end-stage renal disease (ESRD). Affected individuals have a 50% chance of passing the mutation to each of their offspring. Assisted reproductive technology using preimplantation genetic diagnosis (PGD) allows these individuals to reduce this risk to 1% to 2%. We assess the disease burden of 8 individuals with ADPKD who have undergone genetic testing in preparation for PGD. Clinical features that predict high risk for progression to ESRD in patients with ADPKD include genotype, early onset of hypertension, a urologic event before age 35 years, and a large height-adjusted total kidney volume. Patients may have a family history of intracranial aneurysms or complications involving hepatic cysts, which may further influence the decision to pursue PGD. We also explore the cost, risks, and benefits of using PGD. All patients with ADPKD of childbearing potential, regardless of risk for progression to ESRD or risk for a significant disease burden, will likely benefit from genetic counseling.

The Value of Genetic Testing in Polycystic Kidney Diseases Illustrated by a Family With PKD2 and COL4A1 Mutations

The diagnosis of autosomal dominant polycystic kidney disease (ADPKD) relies on imaging criteria in the setting of a positive familial history. Molecular analysis, seldom used in clinical practice, identifies a causative mutation in >90% of cases in the genes PKD1, PKD2, or rarely GANAB. We report the clinical and genetic dissection of a 7-generation pedigree, resulting in the diagnosis of 2 different cystic disorders. Using targeted next-generation sequencing of 65 candidate genes in a patient with an ADPKD-like phenotype who lacked the familial PKD2 mutation, we identified a COL4A1 mutation (p.Gln247*) and made the diagnosis of HANAC (hereditary angiopathy with nephropathy, aneurysms, and muscle cramps) syndrome. While 4 individuals had ADPKD-PKD2, various COL4A1-related phenotypes were identified in 5 patients, and 3 individuals with likely digenic PKD2/COL4A1 disease reached end-stage renal disease at around 50 years of age, significantly earlier than observed for either monogenic disorder. Thus, using targeted next-generation sequencing as part of the diagnostic approach in patients with cystic diseases provides differential diagnoses and identifies factors underlying disease variability. As specific therapies are rapidly developing for ADPKD, a precise etiologic diagnosis should be paramount for inclusion in therapeutic trials and optimal patient management.

Patterns of Kidney Function Decline in Autosomal Dominant Polycystic Kidney Disease: A Post Hoc Analysis From the HALT-PKD Trials

BACKGROUND

Previous clinical studies of autosomal dominant polycystic kidney disease (ADPKD) reported that loss of kidney function usually follows a steep and relentless course. A detailed examination of individual patterns of decline in estimated glomerular filtration rate (eGFR) has not been performed.

STUDY DESIGN

Longitudinal post hoc analysis of data collected during the Halt Progression of Polycystic Kidney Disease (HALT-PKD) trials.

SETTING & PARTICIPANTS

494 HALT-PKD Study A participants (younger; preserved eGFR) and 435 Study B participants (older; reduced eGFR) who had more than 3 years of follow-up and 7 or more eGFR assessments.

MEASUREMENTS

Longitudinal eGFR assessments using the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) creatinine equation.

PREDICTORS

Demographic, clinical, laboratory, and imaging features of participants.

OUTCOMES

Probability of linear and nonlinear decline patterns or of stable eGFR calculated for each participant from a Bayesian model of individual eGFR trajectories.

RESULTS

Most (62.5% in Study A and 81% in Study B) participants had a linear decline in eGFR during up to 8 years of follow-up. A proportion (22% in Study A and 13% in Study B) of progressors had a nonlinear pattern. 15.5% of participants in Study A and 6% in Study B had a prolonged (≥4.5 years) period of stable eGFRs. These individuals (Study A) had significantly smaller total kidney volumes, higher renal blood flows, lower urinary albumin excretion, and lower body mass index at baseline and study end. In Study B, participants with reduced but stable eGFRs were older than the progressors. Two-thirds of nonprogressors in both studies had PKD1 mutations, with enrichment for weak nontruncating mutations.

LIMITATIONS

Relatively short follow-up of a clinical trial population.

CONCLUSIONS

Although many individuals with ADPKD have a linear decline in eGFR, prolonged intervals of stable GFRs occur in a substantial fraction. Lower body mass index was associated with more stable kidney function in early ADPKD.

A potentially crucial role of the PKD1 C-terminal tail in renal prognosis

Background

Autosomal dominant polycystic disease (ADPKD) often results in renal failure. Recently, allelic influences of PKD1 mutation types on renal survival were extensively investigated. Here, we analyzed integrated influences of PKD1 mutation types and positions on renal survival.

Methods

We included 338 (82 pedigrees) and 72 (12 pedigrees) patients with PKD1 and PKD2 mutations, respectively, identified through comprehensive gene analysis of 101 probands with ADPKD. Genetic testing was performed using next-generation sequencing, long-range PCR, and multiplex ligation-dependent probe amplification. Pathogenic mutations were identified by a software package-integrated seven databases and provided access to five cloud-based computing systems.

Results

Mean renal survivals of carriers with PKD1 non-truncating-type mutations at positions upstream of G-protein-coupled receptor proteolytic site (GPS-upstream domain), transmembrane domain, or cytoplasmic C-terminal tail (CTT) domain were 70.2, 67.0, and 50.1 years, respectively (P < 0.0001); renal survival was shorter for mutation positions closer to CTT domain, suggesting its crucial role in renal prognosis. Furthermore, in truncating-type mutations, strong inactivation is anticipated on nucleotides downstream from the mutation site, implying CTT domain inactivation irrespective of mutation site. Shorter mean renal survival was found for PKD1 truncating-type than non-truncating-type mutation carriers (P = 0.0348); mean renal survival was not different between PKD1 3′- and 5′-region truncating-type mutation carriers (P = 0.4375), but was shorter in PKD1 3′-region than in 5′-region non-truncating-type mutation carriers (P = 0.0014). Variable strength of CTT domain inactivation might account for these results.

Conclusions

Aforementioned findings indicate that CTT domain’s crucial role in renal prognosis needs further investigation by larger studies (ClinicalTrials.gov; NCT02322385).

Electronic supplementary material

The online version of this article (doi:10.1007/s10157-017-1477-7) contains supplementary material, which is available to authorized users.

Two autosomal dominant polycystic kidney (ADPKD) cases with advanced renal dysfunction, effectively treated with tolvaptan

We report here two cases of autosomal dominant polycystic kidney disease (ADPKD) with renal dysfunction that were treated with tolvaptan. Case 1 was a 47-year-old man with a glomerular filtration rate (GFR) of 17.0 ml/min/1.73 m² who received tolvaptan treatment (30 mg/day). After treatment, kidney pain was alleviated, and the estimated GFR (eGFR) decline improved from -9.84 ml/min/1.73 m² per year to -4.08 ml/min/1.73 m² per year, respectively. The rate of increase in total kidney volume was reduced from 18 % per year before treatment to 4 % per year following tolvaptan administration. Case 2 was a 44-year-old man with a GFR of 22.6 ml/min/1.73 m², and the eGFR decline improved from -5.76 ml/min/1.73 m² per year before treatment to -3.12 ml/min/1.73 m² per year following tolvaptan treatment (30 mg/day). The rate of increase in total kidney volume was also decreased from 10 % per year before treatment to -7 % per year following tolvaptan administration. These results suggested that tolvaptan may be effective in impeding kidney function aggravation and kidney volume increase in ADPKD patients with advanced renal dysfunction.

Impact of liver volume on polycystic liver disease-related symptoms and quality of life

Background

Symptoms in polycystic liver disease (PLD) are thought to be caused by compression of organs and structures by the enlarged liver.

Aim

The aim of this article is to assess the impact of liver volume on symptoms and quality of life (QoL) in PLD.

Methods

We included PLD patients from two prospective studies that used the PLD-questionnaire (PLD-Q) for symptom assessment. QoL was assessed through SF-36, summarized in a physical (PCS) and mental (MCS) component score. Liver volume was correlated with PLD-Q total scores. Patients were classified based on height-corrected liver volume in mild (<1600 ml), moderate (1600–3200 ml), and severe (>3200 ml) disease. PLD-Q and QoL (PCS and MCS) scores were compared across disease stages.

Results

We included 82 of 131 patients from the original studies (disease stages; mild n = 26, moderate n = 33, and severe n = 23). Patients with larger liver volume reported higher symptom burden (r = 0.516, p < 0.001). Symptom scores increased with disease progression, except for abdominal pain (p = 0.088). PCS decreased with advancing disease (p < 0.001), in contrast to MCS (p = 0.055). Moderate (p = 0.007) and severe (p < 0.001) PLD patients had lower PCS scores than the general population.

Conclusion

PLD with larger liver volume is more likely to be symptomatic and is associated with lower QoL.

Treatment of Persistent Gross Hematuria with Tranexamic Acid in Autosomal Dominant Polycystic Kidney Disease

BACKGROUND/AIMS

In this retrospective study we aimed to compare the effect of tranexamic acid (TXA) vs etamsylate, two hemostatic agents, on hematuria duration in autosomal dominant polycystic kidney disease (ADPKD) patients with persistent gross hematuria.

METHODS

This is a retrospective study of 40 patients with ADPKD and macroscopic hematuria. 20 patients receiving TXA and snake venom blood clotting enzyme injection were compared with 20 matched patients receiving etamsylate and snake venom blood clotting enzyme injection. The primary outcome was hematuria duration and the secondary outcomes were blood transfusion requirements and adverse events.

RESULTS

The hematuria duration was shorter in the TXA group compared with the etamsylate group (4[3-5] d vs 7[6-10] d, P<0.001). The volume of blood transfusion tended to be less in the TXA group than in the etamsylate group (300±115 ml vs 486±195 ml, P=0.12), and the number of patients needing a blood transfusion also tended to be lower [20% (4/20) vs 35% (7/20), P=0.29]. TXA and etamsylate were equally well tolerated and no serious adverse events were observed in both groups.

CONCLUSIONS

Our study indicates that TXA treatment was more effective than etamsylate in stopping bleeding in ADPKD patients with persistent gross hematuria.

PKD2-Related Autosomal Dominant Polycystic Kidney Disease: Prevalence, Clinical Presentation, Mutation Spectrum, and Prognosis

BACKGROUND

PKD2-related autosomal dominant polycystic kidney disease (ADPKD) is widely acknowledged to be of milder severity than PKD1-related disease, but population-based studies depicting the exact burden of the disease are lacking. We aimed to revisit PKD2 prevalence, clinical presentation, mutation spectrum, and prognosis through the Genkyst cohort.

STUDY DESIGN

Case series, January 2010 to March 2016.

SETTINGS & PARTICIPANTS

Genkyst study participants are individuals older than 18 years from 22 nephrology centers from western France with a diagnosis of ADPKD based on Pei criteria or at least 10 bilateral kidney cysts in the absence of a familial history. Publicly available whole-exome sequencing data from the ExAC database were used to provide an estimate of the genetic prevalence of the disease.

OUTCOMES

Molecular analysis of PKD1 and PKD2 genes. Renal survival, age- and sex-adjusted estimated glomerular filtration rate.

RESULTS

The Genkyst cohort included 293 patients with PKD2 mutations (203 pedigrees). PKD2 patients with a nephrology follow-up corresponded to 0.63 (95% CI, 0.54-0.72)/10,000 in Brittany, while PKD2 genetic prevalence was calculated at 1.64 (95% CI, 1.10-3.51)/10,000 inhabitants in the European population. Median age at diagnosis was 42 years. Flank pain was reported in 38.9%; macroscopic hematuria, in 31.1%; and cyst infections, in 15.3% of patients. At age 60 years, the cumulative probability of end-stage renal disease (ESRD) was 9.8% (95% CI, 5.2%-14.4%), whereas the probability of hypertension was 75.2% (95% CI, 68.5%-81.9%). Although there was no sex influence on renal survival, men had lower kidney function than women. Nontruncating mutations (n=36) were associated with higher age-adjusted estimated glomerular filtration rates. Among the 18 patients with more severe outcomes (ESRD before age 60), 44% had associated conditions or nephropathies likely to account for the early progression to ESRD.

LIMITATIONS

Younger patients and patients presenting with milder forms of PKD2-related disease may not be diagnosed or referred to nephrology centers.

CONCLUSIONS

Patients with PKD2-related ADPKD typically present with mild disease. In case of accelerated degradation of kidney function, a concomitant nephropathy should be ruled out.

Tolvaptan and Kidney Pain in Patients With Autosomal Dominant Polycystic Kidney Disease: Secondary Analysis From a Randomized Controlled Trial

Background

Kidney pain is a common complication in patients with autosomal dominant polycystic kidney disease (ADPKD), and data from the TEMPO 3:4 trial suggested that tolvaptan, a vasopressin V2 receptor antagonist, may have a positive effect on kidney pain in this patient group. Because pain is difficult to measure, the incidence of kidney pain leading to objective medical interventions was used in the present study to assess pain.

Study Design

Secondary analysis from a randomized controlled trial.

Setting & Participants

Patients with ADPKD with preserved kidney function.

Intervention

Tolvaptan or placebo.

Outcomes

Kidney pain events defined by objective medical interventions.

Measurements

Kidney pain events were recorded and independently adjudicated. Incidence of a first kidney pain event was assessed overall and categorized into 5 subgroups according to severity.

Results

Of 1,445 participating patients (48.4% women; mean age, 39 ± 7 [SD] years; mean estimated glomerular filtration rate, 81 ± 22 mL/min/1.73 m²; median total kidney volume, 1,692 [IQR, 750–7,555] mL), 50.9% reported a history of kidney pain at baseline. History of urinary tract infections, kidney stones, or hematuria (all P < 0.001) and female sex (P < 0.001) were significantly associated with history of kidney pain. Tolvaptan use resulted in a significantly lower incidence of kidney pain events when compared to placebo: 10.1% versus 16.8% (P < 0.001), with a risk reduction of 36% (HR, 0.64; 95% CI, 0.48–0.86). The reduction in pain event incidence by tolvaptan was found in all groups irrespective of pain severity and was independent of predisposing factors (P for interaction > 0.05). The effect of tolvaptan was explained at least in part by a decrease in incidence of urinary tract infections, kidney stones, and hematuria when compared to placebo.

Limitations

Trial has specific inclusion criteria for total kidney volume and kidney function.

Conclusions

Tolvaptan decreased the incidence of kidney pain events independent of patient characteristics predisposing for kidney pain and possibly in part due to reductions in ADPKD-related complications.

Low-Osmolar Diet and Adjusted Water Intake for Vasopressin Reduction in Autosomal Dominant Polycystic Kidney Disease: A Pilot Randomized Controlled Trial

BACKGROUND

Autosomal dominant polycystic kidney disease (ADPKD) affects millions of people worldwide. Vasopressin promotes disease progression.

STUDY DESIGN

A randomized controlled trial with equal (1:1) allocation.

SETTING & PARTICIPANTS

This trial examined the effect of combining a low-osmolar (low-sodium [1,500mg/d], low-protein [0.8g per kilogram of body weight]) diet and adjusted water intake on vasopressin secretion in 34 patients with ADPKD.

INTERVENTION

Participants were randomly assigned to receive a low-osmolar diet followed by adjusted water intake to achieve urine osmolality ≤ 280mOsm/kg water versus no intervention for 2 weeks.

OUTCOME

The primary outcome of the study was change (delta) in copeptin levels and urine osmolality between the intervention and control groups from baseline to 2 weeks.

MEASUREMENTS

Fasting plasma copeptin level, 24-hour urine osmolality, and total solute intake.

RESULTS

Baseline characteristics of the 2 groups were similar. Mean plasma copeptin levels and urine osmolality declined from 6.2±3.05 (SD) to 5.3±2.5pmol/L (P=0.02) and from 426±193 to 258±117mOsm/kg water (P=0.01), respectively, in the intervention group compared to a nonsignificant change in the control group (from 4.7±3.6 to 5.07±4pmol/L [P=0.2] and 329±159 to 349±139mOsm/kg water [P=0.3], respectively). The change in copeptin levels (primary outcome) and urine osmolality was statistically significant between the intervention and control groups (delta copeptin, -0.86±1.3 vs +0.39±1.2pmol/L [P=0.009]; delta urine osmolality, -167±264 vs +20±80mOsm/kg water [P=0.007], respectively). Total urinary solute decreased in only the intervention group and significantly differed between groups at week 1 (P=0.03), reducing mean water prescription from 3.2 to 2.6L/d.

LIMITATIONS

Small sample size and short follow-up.

CONCLUSIONS

We developed a stepwise dietary intervention that led to a significant reduction in vasopressin secretion in patients with ADPKD. Furthermore, this intervention led to a reduction in water required for vasopressin reduction.

Effect of tolvaptan in a patient with autosomal dominant polycystic kidney disease after living donor liver transplantation

Recently, a large randomized placebo-controlled trial indicated a beneficial effect of tolvaptan on the progression of autosomal dominant polycystic kidney disease (ADPKD) with near-normal kidney function. Meanwhile, the evidence of tolvaptan's efficacy in ADPKD with severe renal insufficiency was limited and higher frequency of liver enzyme elevations were observed in patients taking tolvaptan. Liver transplantation (LT) is the only curative treatment for patients with severe polycystic liver disease associated with ADPKD, but considering that liver injuries should be avoided particularly in patients who underwent LT, we must be careful to start tolvaptan in post-LT ADPKD patients. We describe the case of a patient who had developed severe renal insufficiency after living donor LT, for whom tolvaptan therapy showed marked reduction of total kidney volume and maintenance of renal function without any serious adverse events. This is the first report to show the beneficial effect and safety of tolvaptan, in a post-LT ADPKD patient with severe renal insufficiency, and hopefully will help broaden the spectrum of patients who will benefit from tolvaptan.

Peritoneal dialysis for autosomal dominant polycystic kidney disease: a retrospective study

To describe the long-term clinical outcomes of patients with autosomal dominant polycystic kidney disease (ADPKD) who are on peritoneal dialysis (PD) therapy. We performed a retrospective matched-cohort analysis comparing the clinical outcomes of 30 ADPKD patients with those of 30 non-diabetic patients who had bilateral small kidneys between July 1 2007 and July 31 2014. The patient groups were matched by age, gender, and time of PD initiation. There were no significant differences in the demographic or biochemical parameters, comorbid conditions, residual glomerular filtration rate, or Charlson comorbidity score at the beginning of PD. The median renal volume was 1315 ml for the ADPKD group and 213 ml for the control group. Patients with ADPKD had similar 3-year patient survival (90.6% versus 86.3%, P=0.807) and technique survival (89.2% versus 74.3%, P=0.506) compared with non-ADPKD patients. Also, there was no significant difference in the peritonitis-free survival between the ADPKD and control groups (P=0.22), and rates of peritonitis were similar (0.19 versus 0.21 episodes per patient-year, P=0.26). No differences were observed in the incidence of PD-related complications, such as hernia and dialysate leak. ADPKD is not a contraindication for PD, and a subgroup of ADPKD patients with relatively small kidney volume can be treated using PD.

Bacteremic kidney cyst infection caused by Helicobacter cinaedi

Cyst infection is one of the major complications in patients with autosomal dominant polycystic kidney disease (ADPKD). The causative pathogen in kidney cyst infection frequently goes undetected. Although only one case report of kidney cyst infection caused by Helicobacter cinaedi (H. cinaedi) is published in English literature, it may be an important pathogen in kidney cyst infection. Kidney cyst infection and H. cinaedi infection share the common characteristic of tendency to relapse and chronic kidney disease is a major risk factor for H. cinaedi infection. Moreover, a long period is required to detect H. cinaedi in blood cultures, potentially causing false-negative results. After the identification of H. cinaedi, we must carefully select antibiotics and the antibiotic treatment period should be extended to prevent recurrence. Here we present a case of a 58-year-old male with ADPKD who developed bacteremic kidney cyst infection caused by H. cinaedi. He was admitted to our hospital because of fever, lower left back pain, vomiting, and feeling of abdominal enlargement. H. cinaedi was detected from the blood cultures obtained at admission after 4 days of culture. Antibiotics were administered for 8 weeks after confirming negative blood cultures. There was no evidence of kidney cyst infection relapse at 3 months after treatment completion. Nephrologists should regard H. cinaedi as a challenging but important pathogen in kidney cyst infection, particularly when the causative organism is unknown or kidney cyst infection is recurrent.

Short-term Effects of Tolvaptan in Individuals With Autosomal Dominant Polycystic Kidney Disease at Various Levels of Kidney Function

BACKGROUND

A recent study showed that tolvaptan, a vasopressin V2 receptor antagonist, decreased total kidney volume (TKV) growth and estimated glomerular filtration rate (GFR) loss in autosomal dominant polycystic kidney disease (ADPKD) with creatinine clearance≥60mL/min. The aim of our study was to determine whether the renal hemodynamic effects and pharmacodynamic efficacy of tolvaptan in ADPKD are dependent on GFR.

STUDY DESIGN

Clinical trial with comparisons before and after treatment.

SETTING & PARTICIPANTS

Patients with ADPKD with a wide range of measured GFRs (mGFRs; 18-148 mL/min) in a hospital setting.

INTERVENTION

Participants were studied at baseline and after 3 weeks of treatment with tolvaptan given in increasing dosages, if tolerated (doses of 60, 90, and 120mg/d in weeks 1, 2, and 3, respectively).

OUTCOMES

Change in markers for aquaresis (free-water clearance, urine and plasma osmolality, 24-hour urine volume, and plasma copeptin) and kidney injury (TKV and kidney injury biomarkers).

MEASUREMENTS

GFR was measured by (125)I-iothalamate clearance; TKV, by magnetic resonance imaging; biomarker excretion, by enzyme-linked immunosorbent assay; and osmolality, by freezing point depression.

RESULTS

In 27 participants (52% men; aged 46±10 years; mGFR, 69±39mL/min; TKV, 2.15 [IQR, 1.10-2.77] L), treatment with tolvaptan led to an increase in urine volume and free-water clearance and a decrease in urine osmolality, TKV, and kidney injury marker excretion. Changes in urine volume and osmolality with treatment were less in participants with lower baseline mGFRs (both P<0.01). However, change in fractional free-water clearance was greater at lower baseline mGFRs (P=0.001), suggesting that participants with decreased GFRs responded more to tolvaptan per functioning nephron.

LIMITATIONS

Limited sample size, no control group.

CONCLUSIONS

In patients with ADPKD with decreased kidney function, response to tolvaptan is lower for TKV, urinary volume, and osmolality, but larger for fractional free-water clearance. This latter finding suggests that patients with ADPKD with lower GFRs might benefit from long-term treatment with tolvaptan, as has been observed for patients with preserved GFRs.

Intravascular embolization therapy in patients with enlarged polycystic liver

BACKGROUND

Hepatic transcatheter arterial embolization (TAE) has become an accepted treatment option for patients with symptomatic autosomal dominant polycystic kidney disease (ADPKD) who also have polycystic liver disease and who are not good candidates for surgery. However, indications for TAE and long-term outcome with it are still unclear.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

Symptomatic patients with ADPKD with polycystic liver disease who underwent hepatic TAE, June 2001 to December 2012, at Toranomon Hospital and whose liver volume data were available were studied (N=244; 56% on dialysis therapy, none with kidney transplants). Mean age was 55 ± 9 (SD) years, and mean liver volumes were 8,353 ± 2,807 and 6,626 ± 2,485 cm(3) in men and women, respectively. Target arteries were embolized from the periphery using platinum microcoils.

PREDICTORS

Sex-specific quartiles (6,433, 8,142, and 9,574 cm(3) in men and 4,638, 6,078, and 8,181 cm(3) in women) of total liver volume pretreatment.

OUTCOMES

All causes of mortality were obtained from medical records, followed up until July 31, 2013.

MEASUREMENTS

Laboratory values were measured before TAE and 1, 3, 6, and 12 months after. Organ volumes were measured pretreatment, then 6 and 12 months after, by summing the products of the organ areas traced in each computed tomographic image.

RESULTS

Liver/cyst volume decreased to 94.7% (95% CI, 93.5%-95.8%) at 6 months and 90.8% (95% CI, 88.7%-92.9%) at 12 months of pretreatment volumes. Serum protein and hematocrit values improved significantly without liver damage. Survival was significantly better for patients with liver volume ≤ 9,574 cm(3) (men) and ≤ 8,181 cm(3) (women) than for those with larger livers (5-year survival, 69% and 48%; P=0.02). Infection and liver failure caused most deaths, especially in patients with larger livers.

LIMITATIONS

Referral bias and lack of control group.

CONCLUSIONS

Hepatic TAE appears to be a safe and less invasive option for patients with symptomatic polycystic liver, especially those contraindicated for surgical treatment (eg, with malnutrition or on dialysis therapy), improving both hepatic volume and nutrition.