Severe tubular resistance to aldosterone in a child with familial juvenile nephronophthisis.

A 9.5-year-old girl, whose early symptoms were polyuria and growth retardation, is described. During the progression of her disease, hyperkalaemia developed out of proportion to the degree of renal insufficiency. Her fractional excretion of sodium increased from 3.3% to 35%, and her fractional excretion of potassium decreased from 55% to 22%. The plasma aldosterone level and plasma renin activity (PRA) were very high--290 ng/ml and 100 ng/dl per hour, respectively (normal range for this age 2.6-20.8 ng/ml and 1.2-2.7 ng/ml per hour, respectively). In an attempt to reduce these hormone levels, an acute and sustained saline load, captopril and peritoneal dialysis were used. Only the sustained saline load normalized the PRA, and only peritoneal dialysis sufficiently suppressed the plasma aldosterone level. Successful renal transplantation normalized both plasma aldosterone and PRA. This girl presents the unusual occurrence of pseudohypoaldosteronism type I, during the course of familial juvenile nephronophthisis.