LIGHT AND ELECTRON MICROSCOPE APPEARANCES IN RENAL BIOPSY MATERIAL FROM CASES OF RECURRENT HAEMATURIA IN CHILDREN

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.

The thin glomerular basement membrane in children with haematuria

To determine the specificity and significance of widespread attenuation of the glomerular basement membrane on electron microscopy, 240 renal biopsies from 218 children were studied retrospectively. Twenty-three patients showed diffuse attenuation and three of them are cases of hereditary nephritis. The other 20 patients are characterized by persistent microscopic haematuria, absence of proteinuria, normal blood pressure and renal function, and minimal glomerular changes. In 10 of these 20 children, microscopic haematuria was also present in the family. We conclude that widespread attenuation of the glomerular basement membrane is a characteristic of benign familial and non-familial haematuria. The thin glomerular basement membrane may be responsible for the haematuria and may result from incomplete glomerular maturation.

Segmental glomerulonephritis

The renal biopsy findings in 40 patients with segmental glomerulonephritis are reported. The term is used to describe a condition in which one or more segments of the glomerular tuft is involved by disease when other segments appear unaffected on light microscopy. The word 'focal' is not used as it may be taken to imply that the changes affect some glomeruli but not others and the evidence for this is not convincing. Segmental glomerulonephritis was a relatively common finding in cases of proteinuria with or without the nephrotic syndrome. The severity of the glomerular changes did not correlate with the ultimate prognosis. On the other hand the tubular and interstitial changes, as assessed by a grading procedure and by point counting, were significantly less severe in those patients who showed clinical recovery than in those who did not.

Clinical, light, and electron microscopy findings in idiopathic haematuria

The electron microscopic findings are reported in detail in 20 patients submitted to renal biopsy with the major complaint or clinical finding of gross or microscopic haematuria. The lesions were classified histologically into four groups: group 1, minor glomerular alterations; group 2, focal mesangial thickening and/or cellular proliferation; group 3, diffuse mesangial proliferation; and group 4, other lesions. The major ultrastructural alterations included irregularity in thickness and density of the capillary basement membrane, with apparent discontinuity and bi- or multilaminar splitting of the lamina densa. There were varying degrees of foot process fusion, visceral epithelial polykaryocytosis, and granular deposits related to the capillary basement membrane. Densities were found in the mesangial basement membrane-like material, which was often markedly increased in quantity. A few microtubular aggregates were observed in endothelial cell cytoplasm. Changes consistent with acute diffuse proliferative and membrano-proliferative glomerulonephritis were also seen. The significant clinical findings, histological groups, and ultrastructural changes are correlated.

Recurrent haematuria and mesangial IgA deposition

Six patients are described in whom recurrent haematuria was associated with IgA deposits in the glomerular mesangium. These patients conform closely to the nephropathy described by Berger. The condition can only be definitely diagnosed by immunofluorescence techniques. These six patients were diagnosed in one renal unit within 18 months and, despite the absence of reports from British units, this nephropathy is probably not uncommon. No treatment for it is known at present but the prognosis appears to be good in most patients. Renal failure and hypertension have been reported and long-term follow up is necessary to clarify the natural history of the disease.

Symptomless haematuria in childhood

The clinical, laboratory, and renal biopsy findings in 47 children with symptomless haematuria are reported. In 41 the haematuria was recurrent. Local causes were excluded by means of intravenous urography, which was normal in all but one child, who had a horseshoe kidney.Since all the patients had presented in a similar manner they were classified into four groups according to the severity of glomerular changes on renal biopsy. In group I the glomeruli were optically normal. In group 2 they showed a variable degree of mesangial thickening with absent or minimal cellular proliferation. In group 3 there was diffuse mesangial thickening and proliferation-an appearance indistinguishable from that of subsiding post-streptococcal glomerulonephritis. Compared with groups 1 and 2, more patients in this group had persistent proteinuria, as well as evidence of streptococcal infection preceding the initial haematuria. Only two patients showed severe proliferative glomerulonephritis on biopsy (group 4); both had heavy proteinuria and one repeatedly had low serum beta1(c)-globulin levels.