Calcium-dependent low renin syndrome in a diabetic patient with prostaglandin deficiency.

Calcium and prostaglandin are supposed to play a critical role in the renin-angiotensin aldosterone system. Calcium has been described as an inhibitory second messenger for renin exocytosis whereas vasodilatory prostaglandins, such as PGE2, are known to stimulate the production of renin. These factors are probably interrelated since calcium also enhances urinary prostaglandin release. We report the case of a 52 year-old diabetic patient treated with insulin injections with intestinal malabsorption leading to chronic hyperkalemia and hypocalcemia in whom a low renin syndrome and low levels of urinary prostaglandins were observed. The correction of the hypocalcemia was able to improve plasma renin as well as urinary prostaglandin levels. This observation suggests a prominent role played by calcium on the in vivo regulation of renin and prostaglandin release. These results illustrate the closed loop between plasma calcium level, urinary prostaglandins production and renin release.