Glomerular basement membrane abnormalities associated with apparently idiopathic hematuria: ultrastructural morphometric analysis

Validation of glomerular basement membrane thickness changes with aging in minimal change disease

Measurement of the normal range of glomerular basement membrane (GBM) thickness by electron microscopy is required for the diagnosis of thin basement membrane disease or diabetic nephropathy; however, this measurement is influenced by aging. The aim of this study was to introduce a simple histogram plotting method for the validation of the results of the GBM thickness measurements by the accepted arithmetic mean ± SD method. We examined renal biopsy specimens obtained from 19 patients (10 males and 9 females) with minimal change disease, ranging in age from 3 to 70 years. Renal tissue samples obtained at autopsy from a male baby (3 months old) with no renal disease were also examined. For each case, GBM thicknesses at 10-15 evenly distributed points per glomerular loop were directly measured and the arithmetic mean ± SD was calculated. Subsequently, the arithmetic mean ± SD for each group of cases classified by age into 4 groups, i.e. babyhood (3 months old), childhood (3-11 years old), adulthood (12-57 years old), and old age (60-70 years old), was determined. On the other hand, a histogram of the frequency of GBM points measured against thickness was plotted to determine the distribution pattern and the range of measurements in each age group. The histogram plot showed 4 clearly divided modes for GBM thickness. Comparison of the results obtained by the 2 methods revealed a significant correlation indicating the feasibility of the histogram plotting method as a useful adjunct to validate GBM thickness measurements.

Analysis of the glomerular basement membrane in images of renal biopsies using the split-and-merge method: a pilot study

Abnormal thinning, thickening, or variation in the thickness of the glomerular basement membrane (GBM) are caused by familial hematuria, diabetes mellitus, and Alport syndrome, respectively. We propose a semi-automated procedure for the segmentation and analysis of the thickness of the GBM in images of renal biopsy samples obtained by using a transmission electron microscope (TEM). The procedure includes the split-and-merge algorithm, morphological image processing, skeletonization, and statistical analysis of the width of the GBM. The procedure was tested with 34 TEM images of six patients. The mean and standard deviation of the GBM width for a patient with normal GBM were estimated to be 368 +/- 177 nm, those for a patient with thin GBM associated with familial hematuria were 216 +/- 95 nm, and those for a patient with thick GBM due to diabetic nephropathy were 1,094 +/- 361 nm. Comparative analysis of the results of image processing with manual measurements by an experienced renal pathologist indicated low error in the range of 12 +/- 9 nm.

Segmentation and analysis of the glomerular basement membrane using the split and merge method

Certain renal diseases are characterized by alterations in the thickness of the glomerular basement membrane (GBM), as visualized by images of biopsy samples obtained by using a transmission electron microscope (TEM). Abnormal thinning, thickening, or variation in thickness can occur in familial hematuria, diabetes mellitus, and Alport syndrome, respectively. We propose image processing methods for the segmentation and measurement of the GBM. The methods include the split and merge algorithm, morphological image processing, skeletonization, and statistical analysis of the width of the GBM. The proposed methods were applied to 34 TEM images of six patients. The mean and standard deviation of normal GBM were estimated to be 368 +/- 177 nm; those of thin GBMs associated with familial hematuria were 216 +/- 95 nm; and those of thick GBM due to diabetic nephropathy were 1094 +/- 361 nm. Comparative analysis of the results of image processing with manual measurements by an experienced renal pathologist indicated low error in the range of 12 +/- 9 nm.

Incidence of thin basement membrane nephropathy in 990 consecutive renal biopsies examined with electron microscopy

Thin basement membrane nephropathy is one of the main causes of hematuria in both children and adults. It is often associated with a family history and its true incidence is unknown. Accurate diagnosis of thin basement membrane nephropathy relies on the presence of attenuated glomerular basement membranes, a finding that can be appreciated only by examination in the electron microscope. In Cyprus the department of electron microscopy has received 990 consecutive renal biopsies for diagnosis. The aim of this study is to define the incidence of thin basement membrane nephropathy in this population sample based on the results of electron microscopy.

Segmentation and analysis of the glomerular basement membrane in renal biopsy samples using active contours: a pilot study

Some renal diseases cause changes in the structure of the glomerular basement membranes (GBM). Measurement of the thickness of the GBM can be performed on transmission electron microscopy (TEM) images of renal biopsy samples. Increased thickness of the GBM is observed in patients with diabetic nephropathy. Abnormally thin GBMs are associated with hematuria. We propose image processing methods for the detection and measurement of the GBM. The methods include edge detection, morphological image processing, active contour modeling, skeletonization, and statistical analysis of the width of the GBM. In the present pilot study, the methods were tested with 34 TEM images of six patients. The estimated mean and standard deviation of the GBM width for a patient with normal GBM were 348 +/- 135 nm; those for a patient with thin GBMs due to hematuria were 227 +/- 94 nm; and those for a patient with diabetic nephropathy were 1,152 +/- 411 nm. Comparison with manual measurements by an experienced renal pathologist indicated low error in the range of 36 +/- 11 nm.

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.

Thin basement membrane disease with heavy proteinuria or nephrotic syndrome at presentation

Thin basement membrane disease (TBMD) is a condition originally defined as diffuse thinning of the glomerular basement membrane (GBM) associated with hematuria in all patients. Although proteinuria has been described in up to 60% of patients with TBMD, it is almost always mild, with a 24-hour excretion mostly of less than 500 mg. We describe eight patients (four men and four women between 32 and 66 years of age) with TBMD who presented with heavy proteinuria or nephrotic syndrome. Among the seven cases with family history, hematuria was noted in five. All patients had a long history of microscopic hematuria, with episodic gross hematuria in two. Renal biopsies showed diffuse thinning of the GBM in each patient (mean between 185.3 x 29.8 nm and 232.6 x 34.5 nm versus control between 325 x 35 nm and 350 x 15 nm). Three cases showed thinning of GBM only (group I); the remaining five cases showed thinning of GBM associated with focal segmental glomerulosclerosis. All three patients of group I presented with nephrotic syndrome and normal renal function. Treatment with steroids resulted in remission of nephrotic syndrome in two, whereas nephrotic syndrome persisted in the untreated patient. Among the five patients in group II, nephrotic syndrome and normal renal function at presentation were noted in two, whereas the other three had heavy proteinuria (2.2, 2. 5, and 2.6 g/d, respectively) associated with mildly decreased renal function (serum creatinine 1.8, 1.3, and 1.5 mg/dL, respectively). At last follow-up, although the renal function was stable in all five, only the three who received steroid treatment had remission or marked improvement of proteinuria. Hematuria, however, persisted in all eight patients of both groups. Whether specific gene mutations are translated into structural changes responsible for both excessive GBM thinning and increased transcapillary permeability remains to be elucidated. Alternatively, the heavy proteinuria/nephrotic syndrome may not be related to TBMD, but rather is the manifestation of associated glomerular diseases. Follow-up, including a response to steroids, supports the latter hypothesis.

Thin glomerular basement membranes in patients with hematuria and minimal change disease

A detailed morphometric analysis of glomerular basement membrane (GBM) thickness was carried out on biopsies from 16 patients exhibiting normal histology and unremarkable immunofluorescence. Eleven of these patients presented with proteinuria, 8 in the nephrotic syndrome range, while 5 had hematuria as well. The remaining 5 patients presented with hematuria only. Eight patients had an initial diagnosis of minimal change disease, 4 were diagnosed as thin-membrane nephropathy, 2 had Alport syndrome, and the remaining 2 had hypertensive nephropathy. Quantitative morphometric analysis of GBM identified 3 subsets of patients. The first subset consisted of 6 patients: 5 adults, with an average GBM width of 361 +/- 34 nm, and 1 child. The second subset included 8 patients with thin GBMs and a mean thickness of 253 +/- 15 nm. The last subset comprised 2 patients with Alport syndrome showing marked variability in GBM thickness. This study has confirmed the presence of thin GBMs in hematurics, but has also revealed GBM thinning in 50% of patients with a diagnosis of minimal change disease.

Glomerular basement membrane thickness in primary diffuse IgA nephropathy: ultrastructural morphometric analysis

Sixteen renal biopsy specimens from adult patients with IgA nephropathy (IgAN) for whom both light and electron microscopy as well as immunofluorescence microscopy and full clinical data were available were examined quantitatively and compared with six cases of normal controls. The electron micrographs of the glomeruli were scanned in a Primax flatbed A4 scanner and then morphometric investigations were performed by means of a computer image analysis system to evaluate glomerular basement membrane (GBM) thickness and to study whether this parameter could correlate with the degree of the haematuria, which is thought to be a main renal symptom in this glomerulopathy. The study revealed that the mean value of the GBM thickness was in IgAN patients significantly lower in comparison with normal controls (268.6 nm versus 338.8 nm). The authors also noted the tendency to negative correlation between GBM thinning and haematuria, although this relationship was not significant. It is suggested that deposits located in the vicinity of the capillary loops may play a role in this process.

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

BACKGROUND

Familial persistent microhematuria with normal renal function is the most common presentation of thin basement membrane nephropathy (TBMN). Gross hematuria episodes and loin pain attacks are other manifestations of the disease. On the other hand, it has been shown that hypercalciuria (HC) and hyperuricosuria (HU) can produce both gross or microscopic non-glomerular hematuria, in addition to their role in renal stone formation.

METHODS

We studied the prevalence of HC, HU and nephrolithiasis in a group of 27 biopsy-proven TBMN as well as in 19 non-biopsied first-degree relatives with persistent microhematuria and 25 first-degree relatives without microhematuria. A group of 27 patients with IgA nephropathy (IgAN) and persistent microhematuria, and another group of 20 healthy subjects without known renal diseases were selected as control groups.

RESULTS

Ten (37%) patients with TBMN and 8 (42%) relatives with microhematuria showed HC and/or HU at presentation; relatives without microhematuria, IgAN patients and normal controls showed a significantly lower prevalence of HC and HU. The prevalence of previous nephrolithiasis among TBMN patients (25%) was significantly higher than in IgAN patients (3%; P < 0.05). Family history of nephrolithiasis was recorded in 14 (51%) of the 27 TBMN families, in contrast with 2 of 27 (7%) with IgAN and 1 of 20 (5%) in normal controls (P < 0.05). The prevalence of nephrolithiasis, gross hematuria bouts and loin pain episodes among TBMN patients and microhematuric relatives showing HC and/or HU at presentation (44%, 44% and 27%, respectively) were significantly higher than those of TBMN patients and microhematuric relatives with normal calcium and uric acid urinary excretions (10%, 7% and 3%, respectively; P < 0.05). At the end of follow-up (8.8+/-4.1 years in TBMN patients and 9.1+/-4.2 years in relatives with microhematuria), all the cases maintained normal renal function.

CONCLUSIONS

We found a high prevalence of HC, HU, and nephrolithiasis among TBMN patients and relatives with microhematuria. Our study also shows a significant relationship between the presence of HC and/or HU and the prevalence of nephrolithiasis, gross hematuria bouts and loin pain episodes.

Diagnosis and management of glomerular diseases

Glomerular diseases are a diagnostic challenge. Early recognition and timely institution of appropriate treatment are critical to optimum outcome in many patients, especially those with rapidly progressive glomerulonephritis. The clinical presentations and laboratory data provide adequate presumptive diagnoses in some patients; however, renal biopsy evaluation is often required for a definitive diagnosis.

A practical approach to the diagnosis of renal disease by biopsy

The pathologist has an important role in the diagnosis and monitoring of renal disease. However, for optimal useful information to be derived from renal biopsy specimens, certain guidelines must be adhered to and these are enunciated here. The 3 avenues of observation of renal biopsies viz. light microscopy, immunofluorescence and electron microscopy, all have important roles to play and give differing data which informs the diagnosis for the renal biopsy report. The relative emphasis on each of these modalities of investigation will vary depending upon the situation in which the renal biopsy is performed. The methods used here have been shown to be effective in practice over a period of 20 yrs. Although there may be variations in methodology from centre to centre, the general background aims and principles remain the same. The emphasis in this paper has been on common practical aspects of renal biopsies. Much of the practical information concerning renal biopsies, which is brought together here, is otherwise scattered and not readily available. The aim of this article is to allow the reader to understand the rationale for the steps that are involved in renal biopsy diagnosis.

Association of thin glomerular basement membrane with other glomerulopathies

In the present study we assessed the prevalence of thin glomerular basement membrane (TGBM) in a large group of native kidney biopsies done for evaluation of renal disease. TGBM was present in 54 of 1078 biopsies (5%). In 12 of 54 biopsies (24%), TGBM was the only abnormality present. In the remaining biopsies TGBM was associated with other pathologic diagnoses. The overall prevalence of TGBM in this series is comparable to previous population studies. TGBM is significantly more common in patients with IgA nephropathy and mesangial proliferative glomerulonephritis. Compared to control patients, individuals with TGBM were more likely to have a history of familial hematuria (14% vs. 43%, P = 0.02). Furthermore, examination of urinary sediments in first degree relatives of patients with TGBM demonstrated microscopic hematuria in 92% of families and, in those families, hematuria was present in 47 +/- 6% of relatives. In contrast, hematuria was discovered in 38% of families of control patients, affecting 25 +/- 5% of relatives. In conclusion, the presence of TGBM in a kidney biopsy is highly predictable for the presence of familial microscopic hematuria, even in patients in whom TGBM is associated with another glomerulopathy. The present data also indicate that patients with TGBM nephropathy often have concomitant IgA nephropathy and mesangial proliferative glomerulonephritis.

Inherited diseases of the glomerular basement membrane

The inherited diseases of the glomerular basement membrane include Alport's syndrome (AS), nail-patella syndrome, and thin basement membrane nephropathy. Classical AS is inherited in an X-linked manner and accounts for approximately 85% of the cases. Its manifestations include hematuria, sensorineural hearing loss, ocular defects, and a progression to renal failure. A defect(s) in the alpha 5 (IV) chain of type IV collagen is believed to be the etiology of classic AS, and alterations in its encoding gene localized to the X-chromosome have been elucidated. Although isolated cases of anti-glomerular basement membrane glomerulonephritis have been reported following renal transplantation in patients with AS, it is considered an effective form of renal replacement therapy. Less is known regarding the genetic basis of the autosomal-dominant form of AS, which apparently accounts for the remaining 15% of the cases. Nail-patella syndrome is characterized by nail dysplasia, patellar hypoplasia or aplasia, and nephropathy. It is inherited in an autosomal-dominant fashion with the gene locus assigned to the long arm of chromosome 9. Possible linkage between the COL5A1 gene and the gene for nail-patella syndrome has been suggested. Approximately 30% of the patients progress to end-stage renal failure. Renal transplantation has been successful in treating patients who progress to end-stage renal failure. Thin basement membrane nephropathy is an autosomal dominant trait that accounts for approximately 30% of the cases presenting as persistent, asymptomatic hematuria. The cause of thin basement membrane nephropathy is unknown at present. No decline in renal function is associated with thin basement membrane nephropathy.

Familial lobular glomerulopathy

A family with an unusual lobular glomerulopathy is described. Renal tissue from three males and one female in two successive generations was available for review. The glomerulopathy was characterized by a marked lobular accentuation with only a modest increase in mesangial cellularity. Immunofluorescence in two patients showed focal or diffuse staining with immunoglobulins G, A, M, and C3 in the mesangium and along the glomerular capillary basement membranes. Ultrastructural study showed amorphous granular subendothelial material distending capillary loops and mesangial regions. This material accounted for the pronounced lobular accentuation. The patients in this family presented with proteinuria, hematuria, and hypertension. Three of the four patients have sustained cerebral vascular accidents and two have died. This family is compared with a previously reported family that showed similar glomerular pathology.

Incidence of thin membrane nephropathy: morphometric investigation of a population sample

To explore the incidence of thin membrane nephropathy (thin basement membrane syndrome, benign familial haematuria), glomerular basement membrane thickness was assessed by light and electron microscopy and by morphometry in a series of newly transplanted allograft kidneys, in lieu of normal kidney specimens. Five of the 76 donors possessed an abnormally thin basement membrane, similar to that observed in thin membrane nephropathy, while in two others the measurements fell in the overlap range between thin and normal. Seven donors therefore had a definite or possible basement membrane lesion. After taking account of an additional series of controls, unrelated to transplantation, it is suggested that the incidence of this abnormality in the general population lies between 5.2% and 9.2%. Circumstances did not allow any association between a thin basement membrane and haematuria or other clinical manifestations to be detected.

Thin basement membrane nephropathy as a cause of recurrent haematuria in childhood

A survey of 69 children presenting with recurrent or persistent haematuria and submitted to percutaneous renal biopsy at this hospital over a 17-year period, was performed to establish the incidence of thin basement membrane nephropathy (TBMN). A diagnosis of primary glomerular disease was established in 44 (IgA nephropathy in 16, Alport's syndrome in 13 and other varieties of glomerulonephritis in 15). Of the remaining 25 patients in whom light microscopical and immunochemical examination revealed no abnormalities, material for electron microscopy was available in 11. In eight of these (five of whom had a family history), TBMN was diagnosed on the basis of ultrastructural morphometric evaluation of glomerular basement membrane thickness. Assuming a similar proportion of the remaining 14 patients with renal biopsy specimens normal by light microscopy had TBMN, the probable frequency of this abnormality in the whole series would be 26%, very similar to that of IgA nephropathy. In the eight TBMN patients the mean glomerular basement membrane thickness ranged between 181 and 236 nm, whilst in 'control' biopsies from children with 'minimal change' nephrotic syndrome or IgA nephropathy, the mean thickness ranged between 242 and 333 nm.

Thin basement membranes in minimally abnormal glomeruli

The light microscopic, immunofluorescence, and electron microscopic appearances of renal biopsy specimens were reviewed and correlated with the clinical and laboratory findings in 61 patients in whom the findings were initially considered to be either normal or to show only minor non-specific abnormalities. In all cases this reassessment included quantitative measurement of glomerular basement membrane thickness by an orthogonal intercept technique. On the basis of the indication for biopsy, patients were classified into three groups: those with haematuria (group I, n = 41); those with a minor degree of proteinuria (group II, n = 16); and those without any urinary abnormality but in whom possible renal disease as a result of systemic disease was suspected (group III, n = 6). About half of the patients with haematuria had significantly thinner glomerular basement membranes than those in the other two groups, irrespective of the variable selected for assessment, and in three this was confirmed in follow up biopsy specimens. Follow up for up to eight years showed that in patients either with or without thin basement membranes haematuria commonly persisted, but the long term outlook in all three groups was otherwise good and no patient developed impaired renal function.

Thin-membrane nephropathy--a common cause of glomerular haematuria

Thin-membrane nephropathy recently has been described as a cause of glomerular haematuria. The prognosis of the condition is unclear but it generally is considered to be benign. In a series of 92 patients with glomerular haematuria, thin-membrane nephropathy was found to be a common cause, occurring in 26 (28%) patients. Sixteen patients were women. The mean age was 42 years. Four patients had a family history of renal disease or haematuria and no patient was deaf. Haematuria had been present from six days to 30 years. Loin pain occurred in 31% of patients. Hypertension was not a feature and mild renal impairment was present in one case only, while a further three cases showed proteinuria at a level of greater than 500 mg of protein per day. Glomerular basement membranes in patients with thin-membrane nephropathy gave a mean (+/- standard deviation) width of 319 + 37 nm which was significantly (P less than 0.002) less than the control value of 394 +/- 61 nm. On the basis of clinical features and serological parameters, thin-membrane nephropathy could not be separated from other renal causes of haematuria but required careful electronmicroscopic examination of renal biopsy material to establish the diagnosis. Limited follow-up has confirmed the good prognosis of the condition.

Afferent arteriolar C3 disease--a distinct pathological entity

Afferent arteriolar C3 deposition was the sole histological abnormality in 79 and the major histological abnormality in an additional 39 of 959 renal biopsies performed over a 10-year period. Of these 79 patients, hematuria was the presenting symptom in 90%, with coincident loin pain in 49%. Urine microscopy of asymptomatic first-degree relatives revealed hematuria in 44% of children and siblings and 54% of parents, suggesting autosomal dominant inheritance. Arteriolar C3 deposition was confirmed by biopsy in four asymptomatic relatives with hematuria. Generalized thinning of glomerular basement membrane (less than 200 nm) was observed in five patients and focal thinning was observed in six patients with coincident afferent arteriolar C3 deposition. Seven other patients were identified as having generalized thinning of glomerular basement membrane in the absence of afferent arteriolar C3 deposition. Renal function was stable and similar in all groups studied over 37.9 +/- 23.7 months. No difference in clinical presentation or urinary abnormalities was evident between the groups. No arteriolar C3 deposition was evident in eight autopsy specimens with no known renal disease. It was concluded that afferent arteriolar C3 deposition is a marker of a distinct hereditary pathological entity, with differentiation from thin basement membrane disease not possible on clinical grounds. The medium- and long-term prognoses with respect to renal function are excellent.

Thin-basement-membrane nephropathy in adults with persistent hematuria

Thin-basement-membrane nephropathy, also called benign recurrent hematuria, is characterized by diffuse thinning of the glomerular basement membrane and by hematuria. To determine the incidence of thin-basement-membrane nephropathy among patients with idiopathic hematuria, we conducted a prospective study in the nephrology units of three large hospitals in the Netherlands. Eighty normotensive adults without azotemia underwent renal biopsy because of recurrent macroscopic hematuria (n = 26) or persistent microscopic hematuria (n = 54). Idiopathic IgA nephropathy was found in 27 of the 80 patients. Light microscopical examination showed that 42 patients had normal renal tissue. The remaining 11 patients had mesangioproliferative glomerulonephritis (n = 5), interstitial nephritis (n = 3), or focal global glomerulosclerosis (n = 3). Tissue from the 42 patients whose renal biopsy specimens were normal when examined with light microscopy was analyzed morphometrically with electron microscopy to determine the thickness of the glomerular basement membrane. Two subsets of patients were identified by this analysis. In 18, thin-basement-membrane nephropathy was found (mean basement-membrane thickness [+/- SE], 191 +/- 28 nm; normal, 350 +/- 43 nm); all but one of these 18 patients had microscopic hematuria, which persisted during follow-up (median duration, 50 months). (Of the 54 patients who presented with microscopic hematuria, 17 [31 percent] had thin-basement-membrane nephropathy.) The thickness of the glomerular basement membrane was normal in the other 24 patients (361 +/- 69 nm); during follow-up, hematuria disappeared in all 13 of these patients who had macroscopic hematuria, and hematuria resolved in 5 of the 11 patients who had microscopic hematuria. We conclude that in patients with persistent microscopic hematuria, the incidence of thin-basement-membrane nephropathy is similar to that of idiopathic IgA nephropathy. Morphometric analysis of the thickness of the glomerular basement membrane should be included in the workup of adults with persistent microscopic hematuria that is not of urologic origin.

Alterations of glomerular basement membrane relevant to haematuria

To elucidate the morphological basis of glomerular haematuria, morphometric analysis of the glomerular basement membrane (GBM) and lamina densa (LD) was performed on silver impregnated samples for electron microscopy. The cases studied consisted of 3 groups: group A, normal controls, being from donors for kidney transplantation; group B, haematuric; and group C, non-haematuric cases with isolated proteinuria. Qualitative analysis revealed that gap formation, splitting, segmental and diffuse thinning of the GBM occur preferentially in haematuric cases. The morphometry of the GBM and LD yielded increased mean values of the GBM and of LD thickness in groups B and C. The coefficient of variation (CV, SD/mean) for the GBM and LD, however, was the highest in group B among the 3 groups, suggesting the most irregular GBM and LD in group B. In addition, CV was significantly higher in cases with splitting, segmental attenuation and gap of the GBM than cases without. The findings suggest that the irregularity of the GBM rather than its mean thickness is clearly associated with splitting and ultimately with haematuria via the gaps produced.

Epidemiology of idiopathic glomerular disease: a prospective study

In this study incidence rates of idiopathic glomerular disease in 1.5 X 10(6) Dutch adults between 16 and 65 years of age were determined, as well as the prevalence of these diseases in terms of indication for renal biopsy. The study was conducted between 1978 and 1985; indications for renal biopsy in decreasing hierarchical order were recently discovered uremia, nephrotic syndrome, chronic hematuria of less than two years duration with or without proteinuria or disturbed renal function, and chronic proteinuria of less than two years duration, of unknown origin. The main findings are fourfold. The incidence of IgA nephropathy and thin glomerular basal membrane lesions was high, 19 and 13 per 10(6) adults respectively, and the prevalence in patients biopsied because of non-azotemic chronic hematuria was 31% and 22%, respectively. In the normotensive non-azotemic adults biopsied because of chronic, mild proteinuria the prevalence of focal segmental glomerular sclerosis and vascular hyalinosis was both 41%. Of the patients biopsied because of nephrotic syndrome the prevalence of membranoproliferative glomerulonephritis (5%) was low, as was the incidence (less than 2 per 10(6) adults per year). Finally, the prevalence of diffuse sclerosing glomerulonephritis was 25% in patients biopsied because of uremia. This study is useful for the differential diagnosis of idiopathic glomerular disease.