Oligomeganephronia

Oligomeganephronia (also known as oligonephronia) is a rare congenital renal malformation characterized by a marked reduction in the total number of nephrons (the functional units of the kidney), with the remaining nephrons being abnormally enlarged (hypertrophied). The condition primarily affects the kidneys and is classified as a form of bilateral renal hypoplasia. Both kidneys are small but retain their normal shape, and the reduced nephron population undergoes compensatory hypertrophy, with enlarged glomeruli and tubules attempting to maintain adequate kidney function. Clinically, oligomeganephronia typically presents in infancy or early childhood with polyuria (excessive urination), polydipsia (excessive thirst), dehydration, failure to thrive, and poor growth. Affected children may also develop proteinuria, salt wasting, and a progressive decline in renal function. Because the remaining nephrons are under chronic hyperfiltration stress, the condition gradually leads to chronic kidney disease and eventually end-stage renal disease (ESRD), often by adolescence or early adulthood. Renal biopsy is important for diagnosis, revealing the characteristic finding of markedly enlarged glomeruli with a reduced total nephron count. There is no specific curative treatment for oligomeganephronia. Management is supportive and focuses on optimizing nutrition, maintaining fluid and electrolyte balance, controlling blood pressure, and slowing the progression of chronic kidney disease through measures such as dietary protein restriction and use of renin-angiotensin system inhibitors. Once end-stage renal disease develops, renal replacement therapy (dialysis or kidney transplantation) becomes necessary. Most cases appear to occur sporadically, though rare familial cases have been reported. The condition may occur in isolation or as part of broader syndromes.

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