Oligomeganephronia: an unexpected cause of chronic renal failure.

Oligomeganephronia represents a distinct subgroup of renal hypoplasia in which there is a marked reduction in the number of nephrons with hypertrophy of those that are present. It can only be recognised on renal biopsy. We describe a 14-year-old boy who presents with a history of dysuria and some blood in his pants. Urinalysis showed no hematuria but persistent heavy proteinuria. The size of the kidneys on ultrasound was between -1 to -2 SD for height (right 9.3; left 9.6cm) and both kidneys showed a diffuse increase in echogenicity. The pathological features were diagnostic with a reduced number of greatly enlarged glomeruli indicating oligomeganephronia. No focal segmental glomerulosclerosis was identified but there was subcapsular fibrosis. Hyperfiltration in the small number of nephrons initially maintains the glomerular filtration rate at an acceptable level but by adolescence these children typically have progressive proteinuria, glomerulo-sclerosis and renal failure.