Assessing Risk of Disease Progression and Pharmacological Management of Autosomal Dominant Polycystic Kidney Disease: A Canadian Expert Consensus

Predicting autosomal dominant polycystic kidney disease progression: review of promising Serum and urine biomarkers

Autosomal dominant polycystic kidney disease (ADPKD) is one of the leading causes of end-stage renal disease. In spite of the recent tremendous progress in the understanding of ADPKD pathogenesis, the molecular mechanisms of the disease remain incompletely understood. Considering emerging new targeted therapies for ADPKD, it has become crucial to disclose easily measurable and widely available biomarkers for identifying patients with future rapid disease progression. This review encompasses all the research with a shared goal of identifying promising serum or urine biomarkers for predicting ADPKD progression or response to therapy. The rate of the ADPKD progress varies significantly between patients. The phenotypic variability is only partly explained by the underlying genetic lesion diversity. Considering significant decline in kidney function in ADPKD is not usually evident until at least 50% of the parenchyma has been destroyed, conventional kidney function measures, such as glomerular filtration rate (GFR), are not suitable for monitoring disease progression in ADPKD, particularly in its early stages. Since polycystic kidney enlargement usually precedes the decline in GFR, height-adjusted total kidney volume (ht-TKV) has been accepted as an early biomarker for assessing disease severity in ADPKD patients. However, since measuring ht-TKV is time-consuming and observer-dependent, the identification of a sensitive and quickly measurable biomarker is of a great interest for everyday clinical practice. Throughout the last decade, due to development of proteomic and metabolomic techniques and the enlightenment of multiple molecular pathways involved in the ADPKD pathogenesis, a number of urine and serum protein biomarkers have been investigated in ADPKD patients, some of which seem worth of further exploring. These include copeptin, angiotensinogen, monocyte chemoattractant protein 1, kidney injury molecule-1 and urine-to-plasma urea ratio among many others. The aim of the current review is to provide an overview of all of the published evidence on potentially clinically valuable serum and urine biomarkers that could be used for predicting disease progression or response to therapy in patients with ADPKD. Hopefully, this review will encourage future longitudinal prospective clinical studies evaluating proposed biomarkers as prognostic tools to improve management and outcome of ADPKD patients in everyday clinical practice.

Relationship between disease awareness and severity of kidney disease in autosomal dominant polycystic kidney disease patients

INTRODUCTION

Polycystic kidney disease (PKD) is responsible for 5%-10% of end-stage renal disease. We examined the relationship between renal and extrarenal findings, disease severity, and the level of consciousness of PKD patients.

METHODS

Patients were asked to answer the questionnaire about PKD. Disease severity was determined according to estimated glomerular filtration rate, and disease awareness was assessed by adapting the Disease Perception Scale to PKD. Awareness of patients was evaluated comparatively with chronic kidney disease stage, age, region, and symptoms.

RESULTS

One out of five patients does not know that this disease is inherited. Mean awareness scores of the patients decreased significantly with increasing age. Awareness scores were significantly higher in patients with flank pain, hematuria, and urinary tract stones.

CONCLUSION

Although PKD is the most common hereditary kidney disease, the rate of patients' knowledge on this subject is low. Increased awareness might lead to better treatment in those patients.

Utility of ultrasonography for predicting indications for tolvaptan in patients with autosomal dominant polycystic kidney disease

PURPOSE

Tolvaptan is the first approved treatment for autosomal dominant polycystic kidney disease (ADPKD) that targets a mechanism directly contributing to the development and growth of renal cysts. We investigated the ability of ultrasonography to predict total kidney volume (TKV) of 750 mL or more, which is an indication for tolvaptan therapy in patients with ADPKD.

METHODS

A total of 46 patients with ADPKD were evaluated. The most statistically appropriate measurement based on ultrasonography for predicting TKV determined by computed tomography (CT) was assessed.

RESULTS

TKV determined by CT was 796.8 (508.8-1,560.3) mL. The median length, anteroposterior distance, and mediolateral distance determined using ultrasonography were 15.7 cm, 7.6 cm, and 7.6 cm in the left kidney, and 13.4 cm, 6.9 cm, and 7.2 cm in the right kidney, respectively. Multivariate regression analysis showed that total kidney length (left and right) [variance inflation factor (VIF), 9.349] and total mediolateral distance (left and right) (VIF, 3.988) were independently associated with TKV. The correlation (r) between the logarithm of TKV determined by CT and total mediolateral distance determined using ultrasonography was 0.915 (p < 0.001). The linear regression equation was log (total kidney volume) = 1.833 + 0.075 × total mediolateral distance (left and right) based on ultrasonography. The area under the receiver operating characteristic curve for total mediolateral distance determined using ultrasonography to predict TKV of 750 mL or more was 0.989. Using the total mediolateral distance cut-off value of 14.2 cm, the sensitivity and specificity were 96.0% and 100.0%, respectively.

CONCLUSION

Total mediolateral distance determined using ultrasonography can predict TKV in patients with ADPKD.

Clinical characteristics and risk factors for kidney failure in patients with autosomal dominant polycystic kidney disease: A retrospective study

Autosomal dominant polycystic kidney disease (ADPKD) is a hereditary and progressive renal disease. By the age of 65 years, 45% to 70% of patients with ADPKD reach end-stage renal disease (ESRD). Although there are various treatments for this condition, no standard therapy exists to delay the progression of ADPKD. Hence, understanding the factors that affect disease progression may be helpful for the treatment of ADPKD. The medical records of 288 patients with ADPKD at Keimyung University Dongsan Medical Center between January 1989 and August 2018 were analyzed retrospectively. Furthermore, we inspected the risk factors involved in the progression of ADPKD and the kidney survival rates of patients using the Cox proportional hazards model and Kaplan-Meier survival analysis. The mean age at the time of diagnosis was 43.1 ± 14.1 years, and there were 146 males (50.7%). In total, 197 patients (68.4%) had hypertension and 11 patients (3.8%) had cerebral aneurysm. Stroke occurred in 35 patients (12.1%), including 11 cases of cerebral hemorrhage and 24 cases of cerebral infarction. Twenty-eight patients (9.7%) died during the follow-up period (117.1 ± 102.1 months). Infection (42.9%) was the most common cause of mortality, followed by sudden cardiac death (25.0%). Overall, 132 patients (45.8%) progressed to ESRD and 104 patients (36.1%) required renal replacement therapy (RRT). The mean duration from diagnosis to RRT was 110.8 ± 93.9 months. Age at diagnosis after 30 years (odd's ratio [OR], 2.737; 95% confidence interval [CI], 1.320-5.675; P = .007), baseline serum creatinine levels (OR, 1.326; 95% CI, 1.259-1.396; P < .001), and cyst infection (OR, 2.065; 95% CI, 1.242-3.433; P = .005) were the independent risk factors for kidney failure in multivariable analysis. To delay the advance of ADPKD to ESRD, early diagnosis and close observation for the onset of cyst infection are crucial.

Accuracy, Reproducibility and User Experience With Standardized Instructions for Measurement of Total Kidney Volume in Autosomal Dominant Polycystic Kidney Disease

PURPOSE

Total kidney volume (TKV) measurement is integral in clinical management of autosomal dominant polycystic kidney disease (ADPKD) but the gold standard of measurement via stereology/manual planimetry is time-consuming and not readily available to clinicians. This study assessed whether standardized measurement instructions based on an ellipsoid equation enhanced TKV assessment on computed tomographic (CT) images of the kidneys as determined by accuracy, reproducibility, efficiency and/or user acceptability.

METHODS

Participating radiologists were randomized to perform TKV measurements with or without standardized instructions. All participants measured the same 3 non-contrast, low-dose CT scans. Accuracy was assessed as variation from TKV measurements obtained by planimetry. Intraclass correlation coefficients and time to complete the measurements were assessed. Surveys assessed prior experience with TKV measurement and user acceptability of the instructions.

RESULTS

49 radiologists participated. There was no difference in accuracy or measurement time between instructed and non-instructed participants. There was a trend towards greater reproducibility with standardized instructions (ICC .8 vs .6). 92% of respondents indicated the instructions were easy to use, 86% agreed the instructions would enhance their comfort with TKV measurement and 75% agreed they would recommend these instructions to colleagues.

CONCLUSIONS

Instructed and non-instructed participants demonstrated similar accuracy and time required for TKV measurement, but instructed participants had a trend towards greater reproducibility. There was high acceptability including enhanced user confidence with the instructions. Standardized instructions may be of value for radiologists seeking to improve their confidence in providing clinicians with TKV measurements necessary to appropriately manage this patient population.

Automated measurement of total kidney volume from 3D ultrasound images of patients affected by polycystic kidney disease and comparison to MR measurements

PURPOSE

Total kidney volume (TKV) is the most important imaging biomarker for quantifying the severity of autosomal-dominant polycystic kidney disease (ADPKD). 3D ultrasound (US) can accurately measure kidney volume compared to 2D US; however, manual segmentation is tedious and requires expert annotators. We investigated a deep learning-based approach for automated segmentation of TKV from 3D US in ADPKD patients.

METHOD

We used axially acquired 3D US-kidney images in 22 ADPKD patients where each patient and each kidney were scanned three times, resulting in 132 scans that were manually segmented. We trained a convolutional neural network to segment the whole kidney and measure TKV. All patients were subsequently imaged with MRI for measurement comparison.

RESULTS

Our method automatically segmented polycystic kidneys in 3D US images obtaining an average Dice coefficient of 0.80 on the test dataset. The kidney volume measurement compared with linear regression coefficient and bias from human tracing were R² = 0.81, and - 4.42%, and between AI and reference standard were R² = 0.93, and - 4.12%, respectively. MRI and US measured kidney volumes had R² = 0.84 and a bias of 7.47%.

CONCLUSION

This is the first study applying deep learning to 3D US in ADPKD. Our method shows promising performance for auto-segmentation of kidneys using 3D US to measure TKV, close to human tracing and MRI measurement. This imaging and analysis method may be useful in a number of settings, including pediatric imaging, clinical studies, and longitudinal tracking of patient disease progression.

Total Kidney Volume Measurements in ADPKD by 3D and Ellipsoid Ultrasound in Comparison to Magnetic Resonance Imaging

Background and Objectives: Total kidney volume (TKV) is a validated prognostic biomarker for autosomal dominant polycystic kidney disease (ADPKD). TKV by magnetic resonance imaging (MRI) and manual segmentation is considered the "reference standard", but is time-consuming and not readily accessible. By contrast, 3-dimensional ultrasound (3D ultrasound) provides a promising technology for TKV measurements with unknown potential. Here, we report a comparative study of TKV measurements by 3D ultrasound vs. the conventional methods by ultrasound ellipsoid and MRI ellipsoid. Design, setting, participants, and measurements: Single-center prospective study of 142 patients who completed a standardized 3D ultrasound and MRI. TKV by 3D ultrasound and ultrasound ellipsoid were compared to those by MRI. We assessed the agreement of TKV measurements by Bland-Altman plots and misclassification of the Mayo Clinic Imaging Classes (MCIC) between the different imaging methods, and prediction of MCIC 1C-1E by average ultrasound kidney length >16.5 cm. Results: Compared to MRI manual segmentation, MRI ellipsoid, 3D ultrasound, and ultrasound ellipsoid underestimated TKV (mean difference: -3.2%, -9.1%, and -11.0%) with MCIC misclassified in 11%, 21% and 22% of patients, respectively; most misclassified cases by MRI ellipsoid (11/16), 3D ultrasound (23/30), and ultrasound ellipsoid (26/31) were placed into a lower MCIC. Prediction of the high-risk MCIC (1C-1E) by MRI ellipsoid, 3D ultrasound, and ultrasound ellipsoid all yielded high positive predictive value (96%, 95%, 98%), and specificity (96%, 96%, 99%). However, both negative predictive value (90%, 88%, 95%) and sensitivity (88%, 85%, 94%) were lower for 3D ultrasound and ultrasound ellipsoid compared to MRI ellipsoid. An average ultrasound kidney length >16.5 cm was highly predictive of MCIC 1C-1E only in patients aged <45 years. Conclusions: TKV measurements in ADPKD by 3D ultrasound and ultrasound ellipsoid displayed similar bias, variability, and are less accurate than MRI ellipsoid. Prediction of high-risk MCIC (1C-1E) by all three methods provides high positive predictive value, but ultrasound ellipsoid is simpler to use and more readily available.

The BC ADPKD Network: A Comprehensive Provincial Approach to Support Specialized and Locally Delivered Multidisciplinary ADPKD Care

Purpose:

With evolving evidence around the progression, assessment, and management of autosomal dominant polycystic kidney disease (ADPKD), care of the disease has become increasingly complex. Needs assessments in British Columbia (BC) described variability in knowledge and comfort with incorporating these new aspects of ADPKD care into clinical practice. Undercapture of early-stage ADPKD patients in existing renal databases was also identified as an unmet need.

Sources of Information:

A multidisciplinary group of clinicians and patient partners with interest and expertise in ADPKD and/or multidisciplinary kidney care informed the project work. An existing provincial renal database was used to support the provincial ADPKD registry.

Methods:

A formalized, comprehensive provincial ADPKD Network was created within the existing infrastructure of multidisciplinary kidney clinics (MDCs) in BC. The Network is coordinated provincially and implemented locally. It incorporates robust data collection, education, creation, and dissemination of dedicated clinical tools; collaboration between clinics and clinicians across the province; and ongoing evaluation and continuous quality improvement.

Key Findings:

Over the 5 years since its inception, the BC ADPKD Network has enabled increased and earlier identification of British Columbians living with ADPKD and a shift in practice toward increased and earlier enrollment of ADPKD patients into MDCs. A host of tailored ADPKD clinical tools have been created and implemented in all MDCs across the province to support existing MDC staff in the delivery of more standardized and specialized ADPKD care. A collaborative provincial clinician network founded on Local Clinical Champions has been established to support ongoing experience sharing between clinics. An evaluation framework has been established to evaluate outcomes and enable ongoing refinement of the Network.

Limitations:

The provincial ADPKD registry is undergoing enhancements to enable more comprehensive capture of APDKD-specific information such as total kidney volume and genetic results, but at present, this remains a limitation. It remains to be seen whether the activities of the ADPKD Network will improve long-term clinical outcomes and care experiences of patients living with ADPKD, and a long-term sustainability assessment of this model of care will be required.

Implications:

The structure, tools, and coordinated and collaborative clinician network established through this comprehensive provincial ADPKD Network may be valuable in addressing the variability and gaps in existing ADPKD care while allowing patients and families across BC to receive enhanced care locally, in their usual kidney care environments.

Endothelin-targeted new treatments for proteinuric and inflammatory glomerular diseases: focus on the added value to anti-renin-angiotensin system inhibition

Chronic kidney disease (CKD) is the main cause of end-stage renal disease worldwide arising as a frequent complication of diabetes, obesity, and hypertension. Current therapeutic options, mainly based of inhibition of the renin-angiotensin system (RAS), provide imperfect renoprotection if started at an advanced phase of the disease, and treatments that show or even reverse the progression of CKD are needed. The endothelin (ET) system contributes to the normal renal physiology; however, robust evidence suggests a key role of ET-1 and its cognate receptors, in the progression of CKD. The effectiveness of ET receptor antagonists in ameliorating renal hemodynamics and fibrosis has been largely demonstrated in different experimental models. A significant antiproteinuric effect of ET receptor antagonists has been found in diabetic and non-diabetic CKD patients even on top of RAS blockade, and emerging evidence from ongoing clinical trials highlights their beneficial effects on a wide range of kidney disorders.

Recognizing and treating autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease causes chronic kidney disease and end-stage renal disease. Mechanisms include cyst production, multiplication, and enlargement leading to increased kidney size, and ultimately kidney failure. Although there is no known cure, NPs are uniquely positioned to help patients manage their symptoms and delay onset of kidney failure and need for dialysis.

A Provincial Survey of the Contemporary Management of Autosomal Dominant Polycystic Kidney Disease

Background:

Recent years have witnessed an encouraging expansion of knowledge and management tools in the care of patients with autosomal dominant polycystic kidney disease (ADPKD), including measurement of total kidney volume as a biomarker of disease progression, stringent blood pressure targets to slow cyst growth, and targeted treatments such as tolvaptan.

Objectives:

We sought to evaluate clinicians’ familiarity with, and usage of, novel evidence-based management tools for ADPKD.

Design:

On-line survey.

Setting:

British Columbia, Canada.

Participants:

Nephrologists in academic and community practice (excluding clinicians who practice exclusively in transplantation).

Measurements:

Participants answered multiple-choice questions in 6 domains: sources of information, self-identified needs for optimal care delivery, prognostication, imaging tests, blood pressure targets, and use of tolvaptan.

Methods:

An online survey was developed and disseminated via email to 65 nephrologists engaged in current clinical practice in British Columbia.

Results:

A total of 29 nephrologists (45%) completed the questionnaire. The most popular source of information was the primary literature (83% of respondents). While 86% of respondents reported assessing the risk of disease progression before the onset of kidney function decline, most were using traditional metrics such as blood pressure and proteinuria rather than validated prediction tools such as the Mayo Classification. Although 90% of respondents obtained additional imaging after diagnosis in some or all of their ADPKD patients, only 1 in 5 reported being confident in their ability to interpret kidney size. The recommended blood pressure (BP) target of <110/75 mmHg was sought by 17% of respondents. All respondents reported being familiar with the literature regarding tolvaptan; however, only half were confident in their ability to identify suitable patients for treatment. The top 3 needs identified by clinicians were better access to medications (69%), clear management protocols (66%), and easier access to imaging tests (59%).

Limitations:

Funding mechanisms for tolvaptan can vary; therefore, clinicians’ experience with the drug may not be generalizable. Although the response rate was acceptable, the survey is nonetheless subject to responder bias.

Conclusion:

This survey indicates that there is substantial variability in the usage of, and familiarity with, evidence-based ADPKD management tools among contemporary nephrologists, contributing to incomplete translation of evidence into clinical practice. Providing greater access to tolvaptan or imaging tests is unlikely to improve patient care without enhancing knowledge translation and education.

Trial Registration:

Not applicable as this was a survey.

The Role of Endothelin and Endothelin Antagonists in Chronic Kidney Disease

Background

Endothelins (ET) are a family of peptides that act as potent vasoconstrictors and pro-fibrotic growth factors. ET-1 is integral to renal and cardiovascular pathophysiology and exerts effects via autocrine, paracrine and endocrine signaling pathways tied to regulation of aldosterone, catecholamines, and angiotensin. In the kidney, ET-1 is critical to maintaining renal perfusion and controls glomerular arteriole tone and hemodynamics. It is hypothesized that ET-1 influences the progression of chronic kidney disease (CKD), and the objective of this review is to discuss the pathophysiology, and role of ET and endothelin receptor antagonists (ERAs) in CKD.

Summary

The use of ERAs in hypertensive nephropathy has the potential to decrease proteinuria, and in diabetic nephropathy has the potential to restore glycocalyx thickness, also decreasing proteinuria. Focal segmental glomerular sclerosis has no specific Food and Drug Administration-approved therapy currently, however, ERAs show promise in decreasing proteinuria and slowing tissue damage. ET-1 is a potential biomarker for autosomal dominant polycystic kidney disease progression and so it is thought that ERAs may be of some therapeutic benefit.

Key Messages

Multiple studies have shown the utility of ERAs in CKD. These agents have shown to reduce blood pressure, proteinuria, and arterial stiffness. However, more clinical trials are needed, and the results of active or recently concluded studies are eagerly awaited.

Kidney and cystic volume imaging for disease presentation and progression in the cat autosomal dominant polycystic kidney disease large animal model

BACKGROUND

Approximately 30% of Persian cats have a c.10063C > A variant in polycystin 1 (PKD1) homolog causing autosomal dominant polycystic kidney disease (ADPKD). The variant is lethal in utero when in the homozygous state and is the only ADPKD variant known in cats. Affected cats have a wide range of progression and disease severity. However, cats are an overlooked biomedical model and have not been used to test therapeutics and diets that may support human clinical trials. To reinvigorate the cat as a large animal model for ADPKD, the efficacy of imaging modalities was evaluated and estimates of kidney and fractional cystic volumes (FCV) determined.

METHODS

Three imaging modalities, ultrasonography, computed tomography (CT), and magnetic resonance imaging examined variation in disease presentation and disease progression in 11 felines with ADPKD. Imaging data was compared to well-known biomarkers for chronic kidney disease and glomerular filtration rate. Total kidney volume, total cystic volume, and FCV were determined for the first time in ADPKD cats. Two cats had follow-up examinations to evaluate progression.

RESULTS

FCV measurements were feasible in cats. CT was a rapid and an efficient modality for evaluating therapeutic effects that cause alterations in kidney volume and/or FCV. Biomarkers, including glomerular filtration rate and creatinine, were not predictive for disease progression in feline ADPKD. The wide variation in cystic presentation suggested genetic modifiers likely influence disease progression in cats. All imaging modalities had comparable resolutions to those acquired for humans, and software used for kidney and cystic volume estimates in humans proved useful for cats.

CONCLUSIONS

Routine imaging protocols used in veterinary medicine are as robust and efficient for evaluating ADPKD in cats as those used in human medicine. Cats can be identified as fast and slow progressors, thus, could assist with genetic modifier discovery. Software to measure kidney and cystic volume in human ADPKD kidney studies is applicable and efficient in cats. The longer life and larger kidney size span than rodents, similar genetics, disease presentation and progression as humans suggest cats are an efficient biomedical model for evaluation of ADPKD therapeutics.

CT of Kidney Volume in Autosomal Dominant Polycystic Kidney Disease: Accuracy, Reproducibility, and Radiation Dose

Background Total kidney volume (TKV) assessment is valuable in autosomal dominant polycystic kidney disease (ADPKD) but the reference standard method of MRI planimetry requires access to MRI and time-consuming interpretation. Purpose To determine whether accurate TKV measurements comparable to the resource-intensive reference standard of MRI planimetry can be obtained by using alternate methods including dose-reducing CT protocols and time-saving measurement equations. Materials and Methods In this prospective study conducted September 2016 to June 2017, adult participants with ADPKD underwent one MRI and two CT examinations. Low-dose (LD) and ultra-low-dose (ULD) CT examinations were performed with radiation doses 1.4 and 2.6 times lower, respectively, than the authors' institution's standard abdomen and pelvis CT. ULD CT examinations were reconstructed via model-based iterative reconstruction. Three TKV measurement equations were applied to all image sets, and MRI manual planimetry was the reference standard. Spearman correlation with the reference standard, simple linear regression, and root mean square error (RMSE) calculation analyzed accuracy of these methods; intraclass correlation coefficient examined reproducibility. Results Thirty participants (mean age, 41 years; age range, 24-67 years) had a mean TKV of 1368.9 mL ± 1146.13 (standard deviation). The ULD and LD CT protocols had median dose-length product of 58.8 and 115.5 mGy ∙ cm, respectively (P = .01), and CT dose index of 1.2 and 3.9 mGy, respectively (P < .001). All imaging modalities and measurement equations had excellent correlation with the reference standard (r² > 0.98). RMSE ranged from 80.5 to 157.3 mL (5.9%-11.5% of mean TKV). Intraclass correlation coefficients were greater than 0.98 for all methods. Mean measurement times for the ellipsoid method ranged from 4.6 to 5.2 minutes compared with a mean of 27.7 minutes (range, 14-60 minutes) for manual planimetry. Conclusion Accurate and reproducible total kidney volume measurements comparable to the reference standard of MRI planimetry can be obtained by using a dose-minimizing ultra-low-dose CT protocol and volume measurement based on discrete linear measurements. © RSNA, 2019 Online supplemental material is available for this article.

Autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is the most common hereditary kidney disease and one of the most common causes of end-stage kidney disease. Multiple clinical manifestations, such as enlarged kidneys filled with growing cysts, hypertension, and multiple extrarenal complications, including liver cysts, intracranial aneurysms, and cardiac valvular disease, show that ADPKD is a systemic disorder. New information derived from clinical research using molecular genetics and advanced imaging techniques has provided enhanced tools for assessing the diagnosis and prognosis for individual patients and their families. Phase 3 randomised, placebo-controlled clinical trials have clarified aspects of disease management and a disease-modifying therapeutic drug is now available for patients with high risk of rapid disease progression. These developments provide a strong basis on which to make clear recommendations about the management of affected patients and families. Implementation of these advances has the potential to delay kidney failure, reduce the symptom burden, lessen the risk of cardiovascular complications, and prolong life.

Prenatal detection of isolated bilateral hyperechogenic kidneys: Etiologies and outcomes

OBJECTIVES

To delineate the etiology and outcome of prenatally diagnosed isolated bilateral hyperechogenic kidneys (IBHK).

STUDY DESIGN

Pregnancies with IBHK on prenatal ultrasound identified and followed by us between January 1, 2000 and January 1, 2015 were evaluated regarding the etiology and outcome by evaluation of family history, targeted AR-PKD and AD-PKD DNA analysis, and microarray analysis, according to renal size and amniotic fluid volume.

RESULTS

Of the 52 identified cases, there were 34 cases with enlarged kidneys, 16 with normal size kidneys, and two with small kidneys. There were seven cases with AD-PKD, six inherited, and one with de novo causative variants in the PKD1 gene. Fifteen had AR-PKD, and microarray analysis showed two inherited findings: one with 17q12 deletion including the HNF1B/TCF2 gene inherited from asymptomatic mother and a duplication at 3p26.1 inherited from a healthy father. Of the remaining four cases, three cases had bilateral multicystic dysplastic kidneys, and one had unilateral renal agenesis.

CONCLUSION

Microarray analysis and mutation analysis for PKD1 and PKHD1 have an important contribution to the diagnostic investigation of IBHK and to the management of affected and future pregnancies. Poor outcome was associated with large hyperechoic kidneys with oligohydramnios.

A Practical Guide for Treatment of Rapidly Progressive ADPKD with Tolvaptan

In the past, the treatment of autosomal dominant polycystic kidney disease (ADPKD) has been limited to the management of its symptoms and complications. Recently, the US Food and Drug Administration (FDA) approved tolvaptan as the first drug treatment to slow kidney function decline in adults at risk of rapidly progressing ADPKD. Full prescribing information approved by the FDA provides helpful guidelines but does not address practical questions that are being raised by nephrologists, internists, and general practitioners taking care of patients with ADPKD, and by the patients themselves. In this review, we provide practical guidance and discuss steps that require consideration before and after prescribing tolvaptan to patients with ADPKD to ensure that this treatment is implemented safely and effectively. These steps include confirmation of diagnosis; identification of rapidly progressive disease; implementation of basic renal protective measures; counseling of patients on potential benefits and harms; exclusions to use; education of patients on aquaresis and its expected consequences; initiation, titration, and optimization of tolvaptan treatment; prevention of aquaresis-related complications; evaluation and management of liver enzyme elevations; and monitoring of treatment efficacy. Our recommendations are made on the basis of published evidence and our collective experiences during the randomized, clinical trials and open-label extension studies of tolvaptan in ADPKD.

End-Stage Kidney Disease in Patients With Autosomal Dominant Polycystic Kidney Disease: A 12-Year Study Based on the Canadian Organ Replacement Registry

Background:

Autosomal dominant polycystic kidney disease (ADPKD) is the most common hereditary kidney disease, with afflicted patients often progressing to end-stage kidney disease (ESKD) requiring renal replacement therapy (RRT). As the timelines to ESKD are predictable over decades, it follows that ADPKD patients should be optimized regarding kidney transplantation, home dialysis therapies, and vascular access.

Objectives:

To examine the association of kidney transplantation, dialysis modalities, and vascular access in ADPKD patients compared with a matched, non-ADPKD cohort.

Setting:

Canadian patients from 2001-2012 excluding Quebec.

Patients:

All adult incident ESKD patients who received dialysis or a kidney transplant.

Measurements:

ADPKD as defined by the treating physician.

Methods:

ADPKD and non-ADPKD patients were propensity score (PS) matched (1:4) using demographics, comorbidities, and lab values. Conditional logistic regression and Cox proportional hazards models were used to examine associations with kidney transplantation (preemptive or any), dialysis modality (peritoneal, short daily, home, or in-center hemodialysis [HD]), vascular access (arteriovenous fistula [AVF], permanent or temporary central venous catheter [CVC]), and dialysis survival.

Results:

We matched 2120 ADPKD (99.9%) with 8283 non-ADPKD with no significant imbalances between the groups. ADPKD was significantly associated with preemptive kidney transplantation (odds ratio [OR] = 7.13, 95% confidence interval [CI] = 5.74-8.87), any kidney transplant (OR = 2.37, 95% CI = 2.14-2.63), and initial therapy of nocturnal daily HD (OR = 2.74, 95% CI = 1.38-5.44), whereas in-center intermittent HD was significantly less likely in the ADPKD population (OR = 0.59, 95% CI = 0.54-0.65). There was no difference in peritoneal dialysis (PD) as initial RRT but lower use of any PD among the ADPKD group (OR = 0.85, 95% CI = 0.77-0.95). ADPKD patients were significantly more likely to have an AVF (OR = 3.25, 95% CI = 2.79-3.79) and less likely to have either a permanent (OR 0.68, 95% CI 0.59-0.78) or temporary (OR = 0.49, 95% CI = 0.41-0.59) CVC as compared with the non-ADPKD cohort. Survival on either in-center HD or PD was better for ADPKD patients (HD: hazard ratio [HR] 0.48, 95% CI 0.44-0.53; PD: HR 0.73, 95% CI 0.60-0.88).

Limitations:

Conservative care patients were not captured; despite PS matching, the possibility of residual confounding remains.

Conclusions:

ADPKD patients were more likely to receive a kidney transplant, use home HD, dialyze with an AVF, and have better survival relative to non-ADPKD patients. Conversely, they were less likely to receive PD either as initial therapy or anytime during ESKD. This may be attributed to higher transplantation or clinical decision-making processes susceptible to education and intervention.

Long-term follow up of a boy with unilateral autosomal dominant polycystic kidney disease and contralateral renal agenesis

In patients with autosomal dominant polycystic kidney disease (ADPKD) coexisting abnormalities of the urinary tract are considered rare. Only a few patients with ADPKD and congenital abnormalities of the kidney and urinary tract- renal agenesis, hypoplasia, aplasia, horseshoe kidney, ectopic multicystic dysplasic kidney, or subpelvic junction obstruction were reported. Renal agenesis occurs in approximately 1 in 1.500.000-3.000.000 patients with ADPKD. We report a boy with ADPKD and renal agenesis diagnosed at the age of 12 years. ADPKD was diagnosed in some other members of the family. Additionally to kidney changes, mitral valve prolapse was found on echocardiography. At the age of 18 years high normal blood pressure was recognized and laboratory tests demonstrated: serum creatinine 1.0 mg/dl, glomerular filtrate rate 97.9 ml/min/1.73m2 , isotopic creatinine clearance (Tc-99mDTPA) 99 ml/min/1.73m2 , normal urinalysis, no microalbuminuria.

CONCLUSIONS

In children with positive family history of ADPKD, screening ultrasonography of the kidney performed at the request of the family, allows the early diagnosis of sporadic present abnormalities of the kidney and urinary tract.