Decreased Renal Clearance of Sodium in Cystic Fibrosis

. In 10 patients with cystic fibrosis (CF) and 10 controls of similar age quantitative segmental handling of sodium was estimated by lithium clearance. In the CF group, there was tendency for an increased glomerular filtration rate (GFR) and increased absolute proximal sodium reabsorption. The fractional distal sodium reabsorption was significantly (p=0.015) increased and sodium clearance was significantly (p≤0.01) decreased in CF.