Aldosterone Secretion in Anephric Patients

Serum renin was uniformly absent in 10 anephric patients. Plasma aldosterone concentrations during recumbency were normal with both overhydration and normal hydration. Aldosterone increased significantly after two hours of quiet standing, regardless of hydration. The increase was unrelated to sodium or potassium. A statistical association with an increased cortisol was seen; however, in several subjects, including a steroid-suppressed patient, aldosterone rose distinctly without a corresponding cortisol rise. Dehydration by peritoneal dialysis did not change the recumbent subject's aldosterone levels. ACTH in large doses sharply increased aldosterone in nine of the 10 subjects, including two receiving long-term steroids. We conclude that the renin system plays no part in aldosterone secretion in anephric man. ACTH may be a mediator of the acute postural change, but we suggest there is a still unidentified, additional mechanism for increasing aldosterone. It is triggered by acute volume depletion or other stimulus of quiet standing.