The Aldosterone/Direct Renin Ratio (ADRR) is a vital screening tool used by clinicians to detect primary aldosteronism, a leading cause of secondary high blood pressure.

Aldosterone is a hormone that regulates sodium and water balance, while renin is an enzyme that controls aldosterone production. In a healthy body, these two work in tandem. However, in primary aldosteronism, the adrenal glands overproduce aldosterone independently of renin.

By measuring both levels in the blood and calculating the ratio, doctors can identify an abnormal imbalance—specifically, highly elevated aldosterone alongside suppressed renin levels—signaling the need for further diagnostic testing.