Adult polycystic kidney disease - sodium handling and the renin-angiotensin-aldosterone system

Although most patients with adult polycystic kidney disease (APKD) are hypertensive, a minority have been reported to be sodium wasters. To investigate the ability of polycystic kidneys to produce renin and the integrity of the renin-angiotensin-aldosterone system, a study was carried out in nine patients. Sodium depletion was used to stimulate the system and significant increases in plasma renin activity, plasma aldosterone concentration, and urinary aldosterone excretion indicated appropriate responsiveness. Simultaneously with increased activity of the system, urinary sodium excretion fell significantly in eight of these patients. Reduced urinary sodium excretion was accompanied by increased colonic sodium transport, a transport process thought to depend on aldosterone. These findings suggest that the distal nephron, thought to be unreponsive to antidiuretic hormone in APKD, is probably normally responsive to aldosterone in most of these patients.