Natural history and renal pathology in patients with isolated microscopic hematuria

Variants in genes coding for collagen type IV α-chains are frequent causes of persistent, isolated hematuria during childhood

BACKGROUND

Children with persistent, isolated microscopic hematuria typically undergo a limited diagnostic workup and are monitored for signs of kidney disease in long-term longitudinal follow-up, which can delay diagnosis and allow disease progression in some cases.

METHODS

To determine the clinical utility of genetic screening in this population, we performed targeted genetic testing using a custom, 32-gene next-generation sequencing panel for progressive kidney disease on children referred to the Texas Children's Hospital Pediatric Nephrology clinic for persistent, microscopic hematuria (n = 30; cohort 1). Patients with microscopic hematuria identified by urinalysis on at least two separate occasions were eligible for enrollment, but those with other evidence of kidney disease were excluded. Results were analyzed for sequence variants using the American College of Medical Genetics and Genomics (ACMG) guideline for data interpretation and were validated using a secondary analysis of a dataset of children with hematuria and normal kidney function who had undergone genetic testing as part of an industry-sponsored program (cohort 2; n = 67).

RESULTS

In cohort 1 33% of subjects (10/30) had pathogenic or likely pathogenic (P/LP) variants in the type IV collagen genes (COL4A3/A4/A5), and 10% (3/30) had variants of uncertain significance in these genes. The high diagnostic rate in type IV collagen genes was confirmed in cohort 2, where 27% (18/67) of subjects had P/LP variants in COL4A3/A4/A5 genes.

CONCLUSIONS

Children with persistent, isolated microscopic hematuria have a high likelihood of having pathogenic variants in type IV collagen genes and genetic screening should be considered. A higher resolution version of the Graphical abstract is available as Supplementary information.

Cost Analysis of Screening for IgA Nephropathy Using Novel Biomarkers

OBJECTIVES

IgA nephropathy (IgAN) is the most common primary chronic glomerulonephritis and a major cause of end-stage kidney disease worldwide. Novel biomarkers, including the aberrantly glycosylated IgA1 and glycan-specific antibodies, could be useful in the diagnosis of IgAN. The aim of this study was to assess the cost analysis of IgAN screening using novel biomarkers in addition to the conventional screening compared with conventional screening alone.

METHODS

To estimate the medical expense of each strategy related to renal disease for 40 years, we developed an analytical decision model. The decision tree started at "40 years of age with first-time hematuria." It simulated 2 clinical strategies: IgAN screening using the novel biomarkers (group N) and conventional screening (group C). The analysis results were presented as medical expenses from a societal perspective. Discounting was not conducted.

RESULTS

The expected medical expense per person for 40 years was ¥31.2 million (~$291 000) in group N and ¥33.4 million (~$312 000) in group C; hence, expense in group N was lower by ¥2.2 million (~$21 000). In group N, the expected value of IgAN increased by 5.67% points (N 48.44%, C 42.77%) and that of dialysis introduction decreased by 0.85% points (N 19.06%, C 19.91%). In the sensitivity analysis, expenses could be reduced in almost all cases except when renal biopsy using conventional screening was performed at the rate of 73% or higher.

CONCLUSION

Screening for IgAN using novel biomarkers would reduce renal disease-related expenses.

Minor Glomerular Abnormalities are Associated with Deterioration of Long-Term Kidney Function and Mitochondrial Injury

Minor glomerular abnormalities (MGAs) are unclassified glomerular lesions indicated by the presence of minor structural abnormalities that are insufficient for a specific pathological diagnosis. The long-term clinical outcomes and pathogenesis have not been examined. We hypothesized that MGAs would be associated with the deterioration of long-term kidney function and increased urinary mitochondrial DNA (mtDNA) copy numbers. We retrospectively enrolled patients with MGAs, age-/sex-/estimated glomerular filtration rate (eGFR)-matched patients with immunoglobulin A nephropathy (IgAN), and similarly matched healthy controls (MHCs; n = 49 each). We analyzed the time × group interaction effects of the eGFR and compared mean annual eGFR decline rates between the groups. We prospectively enrolled patients with MGAs, age- and sex-matched patients with IgAN, and MHCs (n = 15 each) and compared their urinary mtDNA copy numbers. Compared to the MHC group, the MGA and IgAN groups displayed differences in the time × group effects of eGFR, higher mean annual rates of eGFR decline, and higher urinary mtDNA copy numbers; however, these groups did not significantly differ from each other. The results indicate that MGAs are associated with deteriorating long-term kidney function, and mitochondrial injury, despite few additional pathological changes. We suggest that clinicians conduct close long-term follow-up of patients with MGAs.

Glomerular isolated microscopic hematuria: urinary features and long term follow-up of a selected cohort of patients

BACKGROUND

Isolated microscopic hematuria is a condition characterized by the presence in the urine of an "abnormal" number of erythrocytes in the absence of proteinuria. Several studies have been published on this condition, but with heterogeneous inclusion criteria and variable outcomes at follow-up. In this retrospective study, we describe a selected and homogenous cohort of patients who presented with isolated microscopic hematuria of glomerular origin.

METHODS

We included in the study patients with isolated microscopic hematuria of glomerular origin (> 1 erythrocyte/high power field at 400× and ≥ 40% dysmorphic erythrocytes and/or ≥ 5% acanthocytes and proteinuria ≤ 150 mg/24 h) with a follow-up of > 60 months from the first documentation of microscopic hematuria.

RESULTS

Forty-two patients (M 12, F 30, age at presentation 14-68 years, eGFR < 60 ml/min/1.73 m²: 1 patient) were included. During a medium term follow-up, microscopic hematuria was persistent in 25 patients (59.5%), transiently absent in 17 (40.5%), always glomerular in 16 patients (38.1%), and occasionally non-glomerular in 26 (61.9%); proteinuria, observed in 16 patients (38.1%), was always transient and < 500 mg/24 h. At the end of a follow-up of 181.8 ± 97.9 (median 168) months, only 2 patients (4.8%) had eGFR < 60 ml/min/1.73 m², one of whom had reduced eGFR already at presentation.

CONCLUSIONS

This study on a small but selected and homogeneous cohort of patients with isolated microscopic hematuria of glomerular origin demonstrates that urinary features can transiently change over time and that the renal outcome is good.

Histopathologic Findings of Potential Kidney Donors With Asymptomatic Microscopic Hematuria: Impact on Donation

INTRODUCTION

Isolated microscopic hematuria (IMH) is not uncommon in potential kidney donors.

AIM

The aim was to study the kidney biopsy findings of potential kidney donors with IMH and the impact of the histopathologic diagnoses on the decision to accept or decline such donors from kidney donation.

METHODS

In this retrospective study, all the potential kidney donors with IMH were identified from the medical records of patients who underwent kidney biopsies between January 2010 and December 2016.

RESULTS

Forty-five such individuals were identified. The mean age of these potential donors was 32.6 years and 76% were male. All of them had normal blood pressure and no significant proteinuria. Seventeen (38%) biopsies showed histopathologic abnormalities; thin basement membrane disease (n = 13; 28%) was the most common cause followed by immunoglobulin (Ig)A nephropathy (n = 4; 9%). Donors with abnormal biopsy findings were excluded from donation. However, 62% of the potential donors had normal kidney biopsy findings and were accepted for kidney donation.

CONCLUSION

IMH justifies extensive work-up including kidney biopsy to identify donors who may have underlying significant glomerular pathology excluding them from kidney donation. On the other hand, kidney biopsy also helps in accepting the donors if it does not show significant abnormality.

The Natural Course of Biopsy-Proven Isolated Microscopic Hematuria: a Single Center Experience of 350 Patients

The increasing interest in healthcare and health screening events is revealing additional cases of asymptomatic isolated microscopic hematuria (IMH). However, a consensus of the evaluation and explanation of the IMH prognosis is controversial among physicians. Here, we present the natural course of IMH together with the pathological diagnosis and features to provide supportive data when approaching patients with IMH. We retrospectively evaluated 350 patients with IMH who underwent a renal biopsy between 2002 and 2011, and the pathological diagnosis and chronic histopathological features (glomerulosclerosis, interstitial fibrosis, and tubular atrophy) were reviewed. Deterioration of renal function was examined during follow up. The patients with IMH were evaluated for a mean of 86 months. IgA nephropathy was the most common diagnosis in 164 patients (46.9%). Chronic histopathological changes were observed in 166 (47.4%) but was not correlated with proteinuria or a decline in renal function. Ten patients developed proteinuria, and all of them had IgA nephropathy. Three patients progressed to chronic kidney disease with an estimated glomerular filtration rate < 60 mL/min/1.73 m(2) but none progressed to end stage renal disease. In conclusion, IMH had a generally benign course during 7-years of observation, although IgA nephropathy should be monitored if it progresses to proteinuria. Future prospective randomized studies may help conclude the long-term prognosis and lead to a consensus for managing IMH.

Proliferative, necrotizing and crescentic immune complex-mediated glomerulonephritis in a cat

Case Summary

A 5-year-old cat was examined for vomiting and anorexia of 2 days’ duration. Azotemia, hyperphosphatemia and hypoalbuminemia were the main biochemical findings. Serial analyses of the urine revealed isosthenuria, proteinuria and eventual glucosuria. Hyperechoic perirenal fat was detected surrounding the right kidney by ultrasonography. Histopathologic evaluation of ante-mortem ultrasound-guided needle biopsies of the right kidney was consistent with proliferative, necrotizing and crescentic glomerulonephritis with fibrin thrombi, proteinaceous and red blood cell casts, and moderate multifocal chronic-active interstitial nephritis. Owing to a lack of clinical improvement, the cat was eventually euthanized. Post-mortem renal biopsies were processed for light microscopy, transmission electron microscopy and immunofluorescence. This revealed severe focal proliferative and necrotizing glomerulonephritis with cellular crescent formation, podocyte injury and secondary segmental sclerosis. Ultrastructural analysis revealed scattered electron-dense deposits in the mesangium, and immunofluorescence demonstrated positive granular staining for λ light chains, consistent with immune complex-mediated glomerulonephritis. Severe diffuse acute tubular epithelial injury and numerous red blood cell casts were also seen.

Relevance and novel information

To our knowledge, this is the first report of naturally occurring proliferative, necrotizing and crescentic immune complex glomerulonephritis in a cat.

Evaluation of microscopic hematuria: a critical review and proposed algorithm

Microscopic hematuria (MH), often discovered incidentally, has many causes, including benign processes, kidney disease, and genitourinary malignancy. The clinician, therefore, must decide how intensively to investigate the source of MH and select which tests to order and referrals to make, aiming not to overlook serious conditions while simultaneously avoiding unnecessary tests. Existing professional guidelines for the evaluation of MH are largely based on expert opinion and have weak evidence bases. Existing data demonstrate associations between isolated MH and various diseases in certain populations, and these associations serve as the basis for our proposed approach to the evaluation of MH. Various areas of ongoing uncertainty regarding the appropriate evaluation should be the basis for ongoing research.

Effect of hematuria on the outcome of IgA nephropathy with mild proteinuria

BACKGROUND

The effects of hematuria on the outcome of IgA nephropathy (IgAN) remain unknown and treatment of IgAN with severe hematuria is controversial.

METHODS

Eighty-eight IgAN patients with proteinuria <0.5 g/day and who had not received corticosteroids, immunosuppressive agents, or undergone a tonsillectomy were divided into two groups: (1) patients with low (<20/high-power field [HPF]) urinary red blood cell (U-RBC) counts (L-RBC group, n = 48); and (2) patients with high (≥20/HPF) U-RBC counts (H-RBC group, n = 40). Clinical and histological findings, renal survival rate and risk factors for progression were analyzed.

RESULTS

The male ratio and blood pressure were significantly higher in the L-RBC group. Median proteinuria, mean estimated glomerular filtration rate and histological findings according to Oxford classifications were similar. During the 5 years after renal biopsy, the median amount of proteinuria remained at <0.5 g/day or g/g creatinine in both groups, and the median U-RBC decreased to <10/HPF in both groups without any intensive therapy. The 15-year renal survival rate, estimated using the Kaplan-Meier method, was 100 % in the H-RBC group, but decreased to 83.4 % in the L-RBC group, although it was not significant. The treatment of inhibitors of renin-angiotensin system (RAS inhibitors) decreased the risk for progression by Cox regression analysis (hazard ratio: 0.14, p = 0.027).

CONCLUSION

Severe hematuria at the time of biopsy naturally improved without any intensive therapy, and there were no negative effects of hematuria on the outcome of IgAN with mild proteinuria. Its prognosis was relatively good, and the treatment of RAS inhibitors might prevent from progression.

Characteristics of IgA nephropathy in advanced-age patients

PURPOSE

The susceptible age for IgA nephropathy (IgAN) is <30 years. However, IgAN sometimes develops in people aged >60 years, and its characteristics remain unknown.

METHODS

We divided 600 IgAN patients into three groups: advanced-age group (AAG, n=31, ≥60 years); middle-aged group (MAG, n=162, 40-59 years); and young-aged group (YAG, n=407, 20-39 years). We analyzed clinical and histological background, renal outcome, and risk of progression.

RESULTS

In the AAG, mean arterial pressure (MAP) and the number of hypertensive patients were significantly higher than in the YAG. Total protein, serum albumin, and estimated glomerular filtration rate were significantly lower, and blood urea nitrogen, proteinuria, and N-acetyl-β-D-glucosaminidase were significantly higher in the AAG than in MAG and YAG. In histological findings, interstitial fibrosis/tubular atrophy by Oxford classification and arteriosclerosis were more severe in the AAG than the in YAG. Renal survival rate analyzed by Kaplan-Meier method was significantly lower in the AAG (22.9%/19 years in the AAG vs. 69.2 and 84.9%/20 years in the MAG and YAG, p<0.0001). The patients who progressed to end-stage renal disease (ESRD) in the AAG had higher MAP and more severe proteinuria compared with the patients who did not progress to ESRD in the AAG.

CONCLUSIONS

The characteristics of IgAN in advanced-age were lower renal function, high levels of proteinuria, severe interstitial change, and arteriolosclerosis caused by glomerulopathy and concomitant diseases, such as hypertension, dyslipidemia, and hyperuricemia. Prognosis was poor, and >70% developed ESRD within 20 years.

Clinicopathological analysis of 155 patients with persistent isolated hematuria

OBJECTIVES

To reveal etiologies of persistent isolated hematuria (PIH) through ultrastructural pathological examination, to disclose clinicopathological correlation in cases with PIH, and to summarize appropriate management of patients with PIH.

METHODS

we retrospectively studied 155 PIH patients receiving renal biopsy between January, 2003 and December, 2008 in Peking Union Medical College Hospital. All the clinical data and follow-up result were analyzed.

RESULTS

All subjects included 38 children and 117 adults, with mean age of 11.38±3.25 years for children and 35.17±8.44 years for adults. Thin basement membrane nephropathy (TBMN) was the most common pathology (55.3% of children and 49.6% of adults), followed by IgA nephropathy (18.4% of children and 32.5% of adults, mainly grade 2-3) and mesangial proliferative glomerulonephritis (MsPGN) without IgA deposition (13.2% of children and 12.8% of adults). Besides, Alport syndrome (2.6% of children) and membrane nephropathy (2.6% of children and 0.9% of adults) were demonstrated as other causes of PIH. Elevated mean arteral pressure or protein excretion rate, as well as episodic macrohematuria, indicated higher risk for MsPGN rather than TBMN. On the other hand, severity of microhematuria was irrelevant to pathological types of PIH. Totally, 86 patients were followed up and 37 cases therein stayed on track for long term (mean duration 41.11?28.92 months, range 8-113 months). Most cases had benign clinical course except 3 cases with TBMN, 5 cases with IgA nephropathy, 1 case with MsPGN (without IgA deposition), and 1 case with Alport syndrome, who developed hypertension or proteinuria. All of them were administered timely intervention.

CONCLUSIONS

Close follow-up should be required as the primary management for PIH. Equally important is careful monitoring for early identification of undesirable predictors; while renal biopsy and other timely intervention are warranted if there is hypertension, significant proteinuria or renal impairment.

In search of a consensus: evaluation of the patient with hematuria in an era of cost containment

OBJECTIVE

The purpose of this article is to describe the current consensus guidelines for nonimaging triage and ultimate preferred imaging approach for the patient with unexplained hematuria.

CONCLUSION

Numerous consensus guidelines from varying societies have outlined preferred imaging pathways for the patient with unexplained urologic causes of hematuria. Future guidelines will need to take into account disease prevalence, radiation considerations, and cost.

Comparison between consecutive and intermittent steroid pulse therapy combined with tonsillectomy for clinical remission of IgA nephropathy

BACKGROUND

In recent years, tonsillectomy and steroid pulse (TSP) therapy have been widely performed in Japan. However, there is no consensus about the treatment protocol and indication.

METHODS

In this retrospective analysis, we compared patients who received tonsillectomy plus intermittent steroid pulse (SP) therapy three times in 6 months (ISP group, n = 44) with patients who received tonsillectomy plus 3 weeks of consecutive SP therapy (CSP group, n = 46) within 1 year after renal biopsy. These two different protocols were performed at two different institutions. We analyzed the clinical and histological background and clinical remission (CR), defined as disappearance of urine abnormalities at 18 months after starting treatment.

RESULTS

Before treatment, there was no significant difference in the clinical findings except for sex between the two groups. In ISP group and CSP group, mean estimated glomerular filtration rate was 82.1 ± 20.9 and 85.9 ± 19.1 ml/min/1.73 m(2), median proteinuria was 0.55 and 0.56 g/day, and median urinary red blood cells were 20 (10-20) and 20 (6-30)/high power filed. The histological (H) grade was lower in the CSP than the ISP group (p = 0.022). The remission rate of proteinuria, hematuria, and rate of CR by the Kaplan-Meier method and logrank test were significantly higher in the CSP group than in the ISP group (CSP vs. ISP group; proteinuria: 97.8 vs. 77.3 %, p < 0.001, hematuria: 97.8 vs. 75.0 %, p = 0.005, CR: 95.6 vs. 63.6 %, p < 0.001). In the Cox proportional hazard model (forced entry), SP protocol and proteinuria before treatment were significantly associated with CR [SP protocol: hazard ratio (HR) 2.50, 95 % confidence interval (CI) 1.46-4.30, p = 0.001, proteinuria: HR 0.81, 95 % CI 0.68-0.96, p = 0.013)]. However H-grade was associated with remission of proteinuria (H-grade: hazard ratio (HR) 0.56, 95 % confidence interval (CI) 0.37-0.85, p = 0.006), and this result meant histological bias affected the remission of proteinuria.

CONCLUSIONS

The difference of the protocol of TSP therapy may have some effect on the CR of IgAN, though the histological bias was observed in this study. The appropriate protocol and indication of TSP therapy must be analyzed and determined in the randomized controlled trial.

Persistent asymptomatic isolated hematuria in children: clinical and histopathological features and prognosis

BACKGROUND

This study involving 351 children who had undergone kidney biopsy secondary to persistent asymptomatic isolated hematuria was undertaken to assess histological diagnosis of the disease and its natural history and prognosis.

METHODS

The patients were divided into two groups: 215 patients with asymptomatic isolated microhematuria (AIMH; proteinuria <0.1 g/day) and 136 patients with persistent asymptomatic microhematuria, recurrent macrohematuria and/or proteinuria (AMHP; proteinuria 0.1-0.25 g/day). After kidney biopsy, the patients were monitored for 2-10 years.

RESULTS

Normal biopsies or minor abnormalities were more frequent in AIMH patients than those in AMHP patients, who exhibited IgA nephropathy more frequently. During the 2- to 10-year follow-up period, adverse renal events (i.e., development of proteinuria, hypertension, or impaired renal function) were observed in 13/215 (6.0%) patients with AIMH and 31/136 (22.8%) patients with AMHP (χ(2)=15.521, P<0.001).

CONCLUSIONS

Normal biopsies or minor abnormalities were more frequently observed in AIMH patients, whereas IgA nephropathy and adverse renal events were more frequent in AMHP. Microscopic hematuria, especially when accompanied by macroscopic hematuria and proteinuria, may represent an important risk factor for the development of chronic kidney disease.

Complete remission within 2 years predicts a good prognosis after methylprednisolone pulse therapy in patients with IgA nephropathy

BACKGROUND

Pozzi et al. reported the effectiveness of steroid pulse therapy (Pozzi's regimen) in IgA nephropathy (IgAN). The present study was performed to clarify the predictive factors for IgAN patients treated with Pozzi's regimen.

METHODS

One hundred nine IgAN patients treated by Pozzi's regimen were observed for up to 112.6 (median 39.7) months, and remission of proteinuria (PR) and disappearance of urinary abnormalities [complete remission (CR)] after Pozzi's regimen were analyzed. Predictive factors for the glomerular filtration rate (GFR) slopes for up to 5 years were analyzed among 81 patients who were observed for at least 2 years. The outcome of a 50 % increase in sCr was compared between the CR and non-CR groups within 2 years.

RESULTS

Cumulative PR and CR rates increased rapidly until 2 years (54.5 and 46.8 % at 2 years), and then slowly but steadily up to 6 years (72.8 and 66.4 % at 6 years). Baseline characteristics of the CR and non-CR groups within 2 years were similar except for proteinuria. GFR slope was steeper in the non-CR group than in the CR group (-2.44 ± 5.12 vs. -0.32 ± 3.34 ml/min/1.73 m(2)/year). On multivariate analysis, sex and CR within 2 years were associated with GFR slope. Kaplan-Meier analysis demonstrated a better survival rate in CR group patients without a 50 % increase in sCr (p = 0.024).

CONCLUSIONS

Among IgAN patients treated with Pozzi's regimen, CR within 2 years predicts a good prognosis.

The role of molecular genetics in diagnosing familial hematuria(s)

Familial microscopic hematuria (MH) of glomerular origin represents a heterogeneous group of monogenic conditions involving several genes, some of which remain unknown. Recent advances have increased our understanding and our ability to use molecular genetics for diagnosing such patients, enabling us to study their clinical characteristics over time. Three collagen IV genes, COL4A3, COL4A4, and COL4A5 explain the autosomal and X-linked forms of Alport syndrome (AS), and a subset of thin basement membrane nephropathy (TBMN). A number of X-linked AS patients follow a milder course reminiscent of that of patients with heterozygous COL4A3/COL4A4 mutations and TBMN, while at the same time a significant subset of patients with TBMN and familial MH progress to chronic kidney disease (CKD) or end-stage kidney disease (ESKD). A mutation in CFHR5, a member of the complement factor H family of genes that regulate complement activation, was recently shown to cause isolated C3 glomerulopathy, presenting with MH in childhood and demonstrating a significant risk for CKD/ESKD after 40 years old. Through these results molecular genetics emerges as a powerful tool for a definite diagnosis when all the above conditions enter the differential diagnosis, while in many at-risk related family members, a molecular diagnosis may obviate the need for another renal biopsy.