[Tubular handling of potassium in cystinosis]

Seven patients with cystinosis (Ccr between 30 and 90 ml/m/1.73 m2), were studied attempting to delineate renal tubular handling of potassium. Ks, Ck/Ccr X 100, Aldou and UAldo V/Ks were determined in basal conditions; tubular handling of water and sodium, and clearance of potassium were studied during hypotonic saline diuresis. Results obtained in cystinosis were compared with normal values and with values found in renal insufficiencies in the same range of GFR. Studies performed indicate that in cystinosis Ks is lower and Ck/Ccr X 100 and UAldo V/Ks higher than in normal children. During hypotonic saline diuresis, patients with cystinosis presented higher fractional water, sodium and potassium clearances than control children with the same range of GFR.