Association of thin basement membrane nephropathy with hypercalciuria, hyperuricosuria and nephrolithiasis

Kidney Biopsy and Type IV Collagen Gene Sequencing Fail to Explain Hematuria in Loin Pain Hematuria Syndrome

Introduction

Loin pain hematuria syndrome (LPHS) is a rare clinical syndrome with a reported prevalence of 1 in 10,000. The syndrome is characterized by severe pain localized to the kidney in the absence of identifiable urinary tract disease. Because of an inadequate understanding of the pathophysiology of the disease, the goal of management has been limited to symptomatic pain management. Through detailed phenotype and genotype assessment we sought to identify possible underlying etiologies.

Methods

We completed a chart review, ultrasound imaging, kidney biopsy, and type IV collagen (COL4A3, COL4A4, and COL4A5) gene sequencing in 14 patients with loin pain hematuria recruited from a single center.

Results

Red blood cells and red cell casts were observed within the tubules in 10 of 14 patients. The glomerular basement membrane (GBM) was normal in 11 patients and thickened in 1 patient. Staining for IgA kappa was present in 1 patient. C3 deposition without any inflammation was present in 7 patients. Arteriolar hyalinosis was present in 4 patients and endothelial cell injury was present in 6 patients. No pathogenic COL4A3, COL4A4, or COL4A5 variants were identified.

Conclusion

Conventional histopathology and genetic testing for type IV collagen variants failed to identify the cause of hematuria in 14 patients with LPHS.

Chronic hepatitis B virus infection increases the risk of upper urinary calculi

Background

Although hepatitis B virus (HBV) is a recognized risk factor for renal diseases, little is known about HBV infection in individuals with upper urinary calculi (UUC). We investigated the relationship between chronic HBV infection and UUC.

Methods

We retrospectively analysed data from 1399 patients who were discharged from the Department of Urology (2017–2018). The diagnosis of UUC was determined using urinary tract ultrasonography or computed tomography, and HBV infection was evaluated by a positive hepatitis B surface antigen (HBsAg) test. Data on patients with and without UUC and HBsAg-positive and HBsAg-negative patients were compared by univariate and multivariate analyses.

Results

Data on chronic HBV infection and UUC were available for 1062 patients, including 514 who presented with UUC and 548 who did not. Overall, 5.8% of total patients, 8.0% of UUC patients and 3.8% of non-UUC patients had chronic HBV infection. UUC patients (41/514) had a significantly higher prevalence of HBsAg positivity (OR 2.175; 95% CI 1.267–3.734; P = 0.004) than non-UUC patients (21/548). After stratifying by sex, the relative odds of HBsAg positivity were statistically significant in men (OR 2.156; 95% CI 1.162–4.003; P = 0.015) but not in women (OR 2.947; 95% CI 0.816–10.643; P = 0.099). The incidence of urinary pH > 6 and staghorn stones was significantly higher in HBsAg-positive UUC patients than in HBsAg-negative UUC patients.

Conclusion

This is the first study to demonstrate that chronic HBV infection is strongly associated with UUC, at least in men. The urinary pH > 6 and staghorn stones were more common in UUC patients with chronic HBV infection.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12894-022-01038-z.

An evaluation of the roles of hematuria and uric acid in defining the prognosis of patients with IgA nephropathy

In recent years, many significant advances have been made in determining which clinical manifestations and pathologic lesions can provide prognostic information for patients with IgA nephropathy (IgAN). However, some important questions remain, including the long-term consequences of hematuria, both macroscopic (MH) and microscopic (mH), in patients with IgAN. The importance of distinguishing patients who have a single episode of MH of long duration from those with recurrent episodes of short duration and the prognostic importance of the episodes of acute kidney injury (AKI) that sometimes accompany episodic MH will be discussed. Studies that have evaluated the mechanisms that may be responsible for recurrent MH and the toxic effects of red blood cells (RBCs), or their constituents, on kidney tubules will also be addressed. In the last section, I will review the evidence that hyperuricemia (HU) may be a significant independent risk factor for progressive kidney disease in patients with IgAN.

Treatment and Management of Loin Pain Hematuria Syndrome

PURPOSE OF REVIEW

Loin pain hematuria syndrome (LPHS) is rare and seldom diagnosed, yet it has a particularly significant impact on those affected. This is a review of the latest and seminal evidence of the pathophysiology and diagnosis of LPHS and presents the typical clinical presentation and treatment options available.

RECENT FINDINGS

LPHS is typically found in young women with characteristic symptoms, including severe recurrent flank pain and gross or microscopic hematuria. The majority of patients will experience crippling pain for many years without effective therapy, often requiring frequent use of narcotic medication. However, the lack of conclusive pathophysiology, in conjunction with the rarity of LPHS, has prohibited the development and trial of definitive treatment options. Nevertheless, in order to combat this rare but severe disease, management strategies have continued to evolve, ranging from conservative measures to invasive procedures. This review presents an overview of the current hypotheses on the pathophysiology of LPHS in addition to summarizing the management strategies that have been utilized. Only 30% of LPHS patients will experience spontaneous resolution, whereas the majority will continue to face chronic, crippling pain. Several methods of treatment, including invasive and non-invasive, may provide an improved outcome to these patients. Treatment should be individually tailored and multi-disciplinary in nature. Further research is required to further elucidate the pathophysiology and develop new, specific, treatment options.

Renal Auto-Transplantation for Loin Pain Hematuria Syndrome Using a Multidisciplinary Team Model: Intermediate-Term Results

Background

Patients with loin pain hematuria syndrome (LPHS) can find relief via multiple modalities, few provide long-term pain control like renal auto-transplantation (RAT). This study evaluates the intermediate effectiveness of the RAT procedure’s ability to achieve long-term pain control and quality of life improvement.

Methods

All patients with suspected LPHS were seen by a multi-disciplinary team (MDT) composed of urologists, interventional radiologists, and transplant surgeons. Clinical history and physical exam, lab values, imaging findings, and response to renal hilar block (RHB) were used to determine LPHS and candidacy for potential RAT. Preoperative, one-year, three-year, and five-year postoperative pain assessment scores and quality of life surveys were administered to each LPHS and potential RAT patient.

Results

Eighty-four LPHS patients were referred for the evaluation of and consultation for the option of RAT. Sixty-four of these patients underwent RHB of which 60 (93.8%) had a positive response, defined as a temporary reduction of pain score by >50%. Forty-six of the 60 patients who responded favorably proceeded to RAT. At the one-year follow-up, there was a 75% reduction in pain with 88.9% of patients experiencing a 50% reduction in pain. At one year, the mean Beck Depression Inventory (BDI) decreased by 65.4%, from an average of 23.7 to 8.2. Similarly, at three years (n = 5) and five years (n = 3), the mean pain scores were 2 and 1.

Conclusions

The MDT evaluation of potential LPHS patients with our protocol and treatment results in an improvement in pain and depression scores in these selected patients.

The idiopathic hypercalciuria reviewed. Metabolic abnormality or disease?

Idiopathic hypercalciuria (IH) is defined as that clinical situation in which an increase in urinary calcium excretion is observed, in the absence of hypercalcemia and other known causes of hypercalciuria. In recent years, its diagnosis in pediatric age has been more frequent because it has been known that it can debut with very different symptoms, in the absence of kidney stone formation. The discovery of genetic hypercalciuric stone-forming rats has allowed us to glimpse the pathophysiological mechanism of IH since they show many data in common with humans with IH as normal levels of blood calcium, intestinal calcium hyperabsorption, increased bone resorption and a defect in the renal tubular calcium reabsorption. In 1993, it was shown that in these animals there is an increase in the number of vitamin D receptors (VDR) in the intestine, which favors an increase in the functional capacity of calcitriol-VDR complexes that explains the increase in intestinal transport of calcium. The same happens at the bone level producing a greater resorption. In our opinion, IH is a 'metabolic anomaly' or, better, an inheritable constitutive metabolic characteristic. In this sense, what patients with IH would inherit is the availability of having a greater number of VDRs in their cells than those with normal urinary calcium excretion. IH cannot be considered a sensu stricto disease, so pharmacological treatment must be individualized.

Renal hilar block predicts long-term success of renal auto-transplantation for loin pain hematuria syndrome

PURPOSE

In patients with loin pain hematuria syndrome (LPHS), a response to percutaneous renal hilar blockade (RHB) and a multidisciplinary team (MDT) evaluation predicts patient's potential renal auto-transplantation (RAT) success.

METHODS

A pain assessment was performed using a 0-10 numeric pain rating scale prior to a percutaneous RHB under CT guidance. If the pain score was reduced > 50% immediately after the RHB, patients were evaluated for RAT by a MDT. Pre-operative and 1-year post-operative quality-of-life surveys were administered to each RAT patient.

RESULTS

43 LPHS patients were referred for RHB. Of the 38 patients who received a RHB, 31 had > 50% reduction in pain scores. Pre- and post-RHB mean pain scores were 6/10 and 0.7/10, respectively, in patients who had > 50% reduction in pain. 22 of the patients who responded favorably then proceeded to RAT. Twelve patients had at least 1-year follow-up after RAT. All patients had a meaningful decrease in their pain. Mean pain score at 1 year was 0.8/10 for an 85% overall reduction in pain. 92% of patients experienced a ≥ 50% reduction in pain at 1 year. Mean Beck Depression Inventory (BDI) score (0-66) 1 year after RAT decreased from 25.2 pre-op (moderate depression) to 12.8 post-op (minimal depression).

CONCLUSIONS

A MDT approach utilizing a RHB should be considered as a tool to select appropriate LPHS patients for RAT to achieve long-term success in reducing chronic pain and depression while increasing quality of life.

[Unilateral renal agenesis. New arguments about the genetic relationship between kidney malformations and urolithiasis]

BACKGROUND

In few previous works, it has been reported that hypercalciuria is associated with some types of CAKUT, namely ureteropelvic junction obstruction, vesicoureteral reflux or simple renal cysts. In addition, one higher prevalence of hypercalciuria and/or urolithiasis has been described in their family members compared to the general population. This study was carried out to find out whether children with unilateral renal agenesis (URA) have these features previously described in other CAKUT types.

METHODS

In a descriptive and multicenter study we studied the prevalence of hypercalciuria, hypocitraturia and urolithiasis in 67 children (43 males and 24 females) with URA and their families.

RESULTS

The two metabolic anomalies that promote stone formation were observed in 26 children (38.8%), distributed as follows: hypercalciuria in 16, hypocitraturia in 9, and both hypercalciuria and hypocitraturia in 1. Eight children (11.9%) suffered renal colic during follow-up. Familial history of urolithiasis was found in 42/67 children (62.7%): in 12 of the first-degree relatives, in 15 of the second degree relatives and in 15 patients both in the first-degree as in their second degree relatives. In contrast, in historic control group, only in 28.1% of families at least one member had urolithiasis.

CONCLUSION

Our results show that the prevalence of hypercalciuria and/or hypocitraturia is greater in pediatric patients with URA than in the general population. Likewise, the prevalence of urolithiasis in the families of these children is also higher than that in the general population.

Metabolic risk factors in children with asymptomatic hematuria

BACKGROUND

Idiopathic or benign hematuria is diagnosed in children after all other possible causes have been ruled out and test results for renal or urologic pathologies are negative.

METHODS

To identify possible urinary risk factors for hematuria in children, we retrospectively evaluated clinical onset, family history, and metabolic risk factors of 60 children with idiopathic hematuria but without renal stones or other pathologic conditions that could explain the hematuria. All patients followed the same ambulatory protocol at that used to evaluate kidney stone-formers.

RESULTS

Seven patients had microhematuria, three patients each had microhematuria and gross hematuria, and the remaining 50 patients had gross hematuria onset. A family history of stone disease was found in 63 % of the children. At least one urinary metabolic abnormality was present in 49 patients, while 11 patients had no metabolic abnormality. The most common urinary risk factor was idiopathic hypercalciuria (single or associated), which was found in 43.5 % of patients, followed by hypocitraturia (single or associated), present in 31.7 %. Unduly acidic urine pH as a single abnormality was found in 10 % of this pediatric patient population. We also found hyperoxaluria and, less frequently, hypomagnesuria, and hyperuricosuria.

CONCLUSIONS

Asymptomatic idiopathic hematuria in pediatric patients may often be associated to different urinary biochemical abnormalities, similar to what is observed in pediatric kidney stone-formers.

Loin pain hematuria syndrome

Loin pain hematuria syndrome (LPHS), first described in 1967, is a rare pain syndrome, which is not well understood. The syndrome is characterized by severe intermittent or persistent flank pain, either unilateral or bilateral, associated with gross or microscopic hematuria. LPHS is a diagnosis of exclusion as there still is not a consensus of validated diagnostic criteria, though several criteria have been proposed. The wide differential diagnosis would suggest a meticulous yet specific diagnostic work-up depending on the individual clinical features and natural history. Several mechanisms regarding the pathophysiology of LPHS have been proposed but without pinpointing the actual causative etiology, the treatment remains symptomatic. Treatment modalities for LPHS are diverse including simple analgesia, opioid analgesic and kidney autotransplantation. This review article summarizes the current understanding regarding the pathophysiology of LPHS along with the steps required for proper diagnosis and a discussion of the different therapeutic approaches for LPHS.

Induced urinary crystal formation as an analytical strategy for the prediction and monitoring of urolithiasis and other metabolism-related disorders

Crystal formation reflects the entire composition of the surrounding solution. In case of urolithiasis, induced crystal formation in native urine has led to the development of the Bonn-Risk-Index (BRI), a valuable tool to quantify an individual's risk of calcium oxalate urolithiasis. If the progression of a disease is associated with characteristic changes in the activities of urinary components, this leads to an altered urinary crystallisation capacity. Therefore, the results of induced urinary crystal formation can be used to detect and monitor any disease linked to the altered urinary composition. Since crystal formation inherently takes into account the entire urinary composition, the influence of the disease on individual urinary parameters does not have to be known in order to monitor the consequent pathologic alterations. In this paper, we review the background of urinary crystal formation analysis and describe its established application in urolithiasis monitoring as well as potential further fields of clinical application.

Multiple kidney cysts in thin basement membrane disease with proteinuria and kidney function impairment

Background

Some patients with thin basement membrane disease (TBMD) develop proteinuria, hypertension and different degrees of CKD, besides the persistent microhaematuria characteristic of the disease. Little is known about factors associated with this unfavourable outcome.

Methods

We reviewed clinical, pathological and radiological features of 32 patients with biopsy-proven TBMD. Patients were divided in two groups: those with persistent normal kidney function and negative or minimal proteinuria (n = 16) and those with persistent proteinuria >0.5 g/day (n = 16).

Results

Patients with proteinuria had a worse kidney function at baseline than those with negative proteinuria. Global or segmental glomerulosclerosis, together with interstitial fibrosis, was found in 37% of patients with proteinuria. All proteinuric patients were treated with renin–angiotensin system blockers. At the end of follow-up (198 months in proteinuric patients and 210 months in patients with negative proteinuria) the prevalence of hypertension was 68% in proteinuric patients (12% at baseline), compared with 12 and 6%, respectively, in non-proteinuric patients. A slow decline of renal function was observed in proteinuric patients, although no patient developed end-stage kidney disease. Ultrasound studies showed bilateral kidney cysts in nine patients (56%) with proteinuria. Cysts were bilateral and countless in six patients, and bilateral but with a limited number of cysts in the three remaining patients. No cysts were found in patients with negative proteinuria.

Conclusions

Some patients with TBMD develop hypertension, proteinuria and CKD. Multiple bilateral kidney cysts were found in a majority (56%) of these patients. Further studies are needed to investigate the pathogenesis and the influence on long-term outcome of this TBMD-associated multiple kidney cysts.

Novel heterozygous COL4A3 mutation in a family with late-onset ESRD

Thin basement membrane nephropathy (TBMN) and Alport syndrome (ATS) are genetically heterogeneous conditions characterized by structural abnormalities in the glomerular basement membrane (GBM). TBMN presents with hematuria, minimal proteinuria, and normal renal function. Although TBMN is an autosomal dominant disease (COL4A3 and COL4A4), ATS can be inherited X-linked (COL4A5), autosomal recessive, or autosomal dominant (both COL4A3 and COL4A4). The clinical course of TBMN is usually benign, whereas ATS typically results in end-stage renal disease (ESRD). Nevertheless, there is a broad spectrum of clinical phenotypes caused by mutations in COL4A3 or COL4A4. We report an Italian family who presented with hematuria and mild proteinuria. Mutational analysis showed a novel heterozygous mutation p.G291E in exon 15 of the COL4A3 gene. Many different mutations in COL4A3 and COL4A4 that cause TBMN have already been identified, but most genetic variability in these genes has been found to cause autosomal ATS. A valid genotype-phenotype correlation for TBMN or ATS is not yet known. Therefore, it is important to identify new mutations by direct sequencing to clarify their clinical importance, to assess the prognosis of the disease, and to avoid renal biopsy.

[From Alport syndrome to benign familial hematuria: clinical and genetic aspect]

Alport syndrome (AS) is a hereditary glomerulonephritis variably associated with neural hearing loss and ocular abnormalities. The prevalence of the disease is estimated at approximately 1 in 50,000 live births. AS arises from mutations in genes encoding alpha chains constituting type IV collagen. In 85% of patients, the disease results from mutations in the COL4A5 gene located on X chromosome. In the hemizygous male, persistent microhematuria is present from early life, then proteinuria and renal insufficiency occur with time, leading to end-stage renal failure before age 40. In the heterozygous female, clinical manifestations vary from completely healthy state to end-stage renal failure, most often reached after the age of 40. In 15% of patients, the disease results from mutations in either the COL4A3 or the COL4A4 gene, both located on chromosome 2. When both alleles are mutated (autosomal recessive form), the phenotype is constantly severe, resembling that of the hemizygous male in the X-linked form. In the heterozygous individual, the clinical spectrum vary from the absence of any manifestation to the development of proteinuria - the so-called autosomal-dominant AS -, and even renal insufficiency, sometimes reaching end-stage (after the age of 40) through the most frequently encountered phenotype, i.e. a persistently isolated microhematuria, accounting for the so-called benign familial hematuria (or healthy carrier state). The determinants of the phenotype remain largely unknown, so that it may be risky to predict renal prognosis in the individual with a single COL4A3/A4 mutation and an isolated microhematuria at the time of examination.

Evaluation of gross hematuria

Gross hematuria in children is a common complaint that often leads patients to seek urgent care. The diagnostic evaluation can be chosen based on specific patient history and physical examination. When a patient is asymptomatic, hypercalciuria and mild forms of glomerulonephritis are common causes of gross hematuria. Although they are less common in children, special care should be taken to investigate for renal and bladder tumors.

Proposed pathogenesis of idiopathic loin pain-hematuria syndrome

BACKGROUND

To study loin pain-hematuria syndrome (LPHS) pathogenesis, we evaluated 43 consecutive patients for whom urological evaluation failed to disclose the cause of their recurrent flank pain and hematuria. Each underwent percutaneous kidney biopsy. In 9 patients, the biopsy specimen showed immunoglobulin A nephritis, an established cause of LPHS. We suggest these cases be designated secondary LPHS. They are not included in this analysis. The remaining patients (N = 34) are designated idiopathic (primary) LPHS. They are the basis of this report.

METHODS

Demographics of patients with primary LPHS are mean age of 30.8 +/- 10.3 years; 74% women; 94% white; and history of kidney stones, 47%, although none was obstructing.

RESULTS

Primary LPHS kidney biopsy specimens showed red blood cells (RBCs) in multiple tubules, consistent with glomerular hematuria. Glomeruli were normal by means of light and immunofluorescent microscopy; however, more than 50% of biopsy specimens showed unusually thin or thick glomerular basement membranes. To assess whether the biopsy itself caused RBCs in tubules, we compared RBCs in renal tubular cross-sections from primary LPHS biopsies with those of normal kidneys (donors, n = 10). The mean percentage of tubular cross-sections containing RBCs was greater in primary LPHS than normal specimens (7.2% +/- 6.5% versus 1.6% +/- 1.0% [SD]; P < 0.0001), confirming glomerular hematuria in patients with primary LPHS.

CONCLUSION

Primary LPHS pathogenesis includes glomerular hematuria, apparently from structurally abnormal glomerular basement membrane. Primary LPHS pain may be initiated by obstructing RBC casts and perhaps microcrystals in those with a history of urolithiasis. Nevertheless, other factors are needed to explain the severe pain in patients with primary LPHS.

Nephrolithiasis in children

A metabolic etiology is the most common cause for pediatric kidney stones. Appropriate evaluation of affected children should include assessment of stone type, if available, and assessment of predisposing factors in all cases. This review discusses the metabolic disorders that lead to nephrolithiasis with respect to the development of calcium, uric acid, struvite, and cystine stones. Environmental and hereditary factors are summarized to provide a guide in the evaluation of pediatric stone formers.

Thin basement membrane nephropathy

Thin basement membrane nephropathy. Thin basement membrane nephropathy (TBMN) is the most common cause of persistent glomerular bleeding in children and adults, and occurs in at least 1% of the population. Most affected individuals have, in addition to the hematuria, minimal proteinuria, normal renal function, a uniformly thinned glomerular basement membrane (GBM) and a family history of hematuria. Their clinical course is usually benign. However, some adults with TBMN have proteinuria >500 mg/day or renal impairment. This is more likely in hospital-based series of biopsied patients than in the uninvestigated, but affected, family members. The cause of renal impairment in TBMN is usually not known, but may be due to secondary focal segmental glomerulosclerosis (FSGS) or immunoglobulin A (IgA) glomerulonephritis, to misdiagnosed IgA disease or X-linked Alport syndrome, or because of coincidental disease. About 40% families with TBMN have hematuria that segregates with the COL4A3/COL4A4 locus, and many COL4A3 and COL4A4 mutations have now been described. These genes are also affected in autosomal-recessive Alport syndrome, and at least some cases of TBMN represent the carrier state for this condition. Families with TBMN in whom hematuria does not segregate with the COL4A3/COL4A4 locus can be explained by de novo mutations, incomplete penetrance of hematuria, coincidental hematuria in family members without COL4A3 or COL4A4 mutations, and by a novel gene locus for TBMN. A renal biopsy is warranted in TBMN only if there are atypical features, or if IgA disease or X-linked Alport syndrome cannot be excluded clinically. In IgA disease, there is usually no family history of hematuria. X-linked Alport syndrome is much less common than TBMN and can often be identified in family members by its typical clinical features (including retinopathy), a lamellated GBM without the collagen alpha3(IV), alpha4(IV), and alpha5(IV) chains, and by gene linkage studies or the demonstration of a COL4A5 mutation. Technical difficulties in the demonstration and interpretation of COL4A3 and COL4A4 mutations mean that mutation detection is not used routinely in the diagnosis of TBMN.

Childhood stones

Urinary stones in children are usually genetic and most commonly due to hypercalciuria. Symptoms of urolithiasis in children differ among age groups. Isolated hematuria in children may be caused by hypercalciuria and precede calculus formation. Careful evaluation successfully identifies the cause of urinary stones in most children, although diagnostic criteria may vary in different age groups. Therapies should be targeted to the underlying diagnosis.

Familial microscopic hematuria caused by hypercalciuria and hyperuricosuria

We report 12 patients belonging to five different families in whom persistent isolated microhematuria was associated with hypercalciuria and/or hyperuricosuria. Four patients had episodes of gross hematuria, three patients had passed renal stones, and a history of nephrolithiasis was obtained in four of the families (80%). Calcium oxalate and uric acid crystals were commonly observed in the urine sediments. Urinary erythrocytes had a normal appearance on phase-microscopic examination. Reduction of calciuria and uricosuria by thiazide diuretics, allopurinol, forced fluid intake, and dietetic measures led to a persistent normalization of urine sediment with complete disappearance of hematuria. Determination of calcium and uric acid urinary excretions should be included in the study of familial hematuria.