Nephrotic syndrome in infancy can spontaneously resolve.

Nephrotic syndrome in the first year of life (NSFL) is a heterogeneous group of disorders, the management of which is supportive, as most patients do not respond to immunosuppression. Prognosis is guarded, as the syndrome tends to lead to end-stage renal failure. We describe four cases, all of which went into spontaneous remission. These patients had severe nephrosis that began postnatally at ages 15 days to 7 months and had preceding symptoms of viral infections. One infant had proven pertussis and required ventilation for respiratory failure. Renal biopsies showed varying degrees of mesangial expansion and increased cellularity. Two biopsies showed mild mesangial sclerosis and the other two only scattered globally sclerosed glomeruli. Supportive treatment was started with 20% albumin infusions, diuretics, penicillin, and thyroxine. Angiotensin-converting enzyme (ACE) inhibitors were used to reduce proteinuria in all infants, and one was also treated with indomethacin. The nephrosis gradually resolved, and protein-lowering medications were successfully weaned completely 5-30 months after presentation. The patients were protein free with normal renal function at last follow-up. Investigations including viral studies and autoimmune profiles were negative. Genetic studies for NPHS1, NPHS2, WT1, and LAM-β were negative. We therefore describe a subgroup of NSFL with good prognosis associated with infectious prodromes. This is also the first-described case of pertussis causing nephrotic syndrome.