Aldosterone renin ratio in patients with resistant hypertension.

Sir, Essential hypertension resistant to treatment often warrants suitable investigations to exclude underlying secondary causes. Aldosterone renin ratio (ARR) is an effective diagnostic tool for detecting primary hyperaldosteronism among patients with presumed essential hypertension. Further confirmation of existing adrenal tumours or hyperplasia can be obtained with imaging studies such as high-resolution computed tomography (CT) scans. Appropriate timing of the laboratory tests for ARR is essential for reliability of results as posture, anti-hypertensive medications tends to interfere with the values. We present a few cases of patients with established and resistant hypertension in whom estimation of ARR was valuable as a part of their work up to ascertain a definitive diagnosis. We also present a brief review of the contemporary literature. A 60-year-male was being investigated for hyperten-sion with hypokalaemia. He was treated with dox-azosin, atenolol, losartan and amiloride with regular monitoring of renal function and electrolytes, which revealed a low potassium (usually <3.6 mmol/l) and raised sodium on multiple occasions. His aldoster-one level was 351 pmol/l with a renin level of 0.39 mg/l.h with the ambulant ARR of 900 pmol/l per mg/l.h. Urinary cortisol was normal and an ultra-sound of abdomen was normal as well but the CT scan of abdomen showed a left adrenal mass of 2 Â 2 cm size that was consistent with a left adrenal adenoma. A 57-year-old gentleman with diabetes, hyperten-sion and angina was noted to have persistently raised blood pressure in spite of maximal treatment with amlodipine, lisinopril, spironolactone and moxonidine. He was investigated for resistant hyper-tension, which revealed normal electrolytes and renal function and a urine-free cortisol level of 164 nmol/day. Further investigations revealed an aldosterone level of 746 pmol/l and renin of 0.21 mg/l.h and ARR of 3552 pmol/l per mg/l.h. A CT scan of his abdomen showed a 9-mm sized right adrenal adenoma. A 45-year-old gentleman was referred by the general practitioner (GP) with a suspicion of Conn's syndrome with raised blood pressure and low potassium at the GP surgery. He was taking atenolol and clonidine at the time of presentation but had been on angiotensin-converting enzyme (ACE) inhi-bitors and diuretics before. His sodium level was 144 mmol/l and potassium was 3.7 mmol/l and his aldosterone levels were 385 pmol/l and the renin level was 0.05 mg/l.h with an aldosterone rennin ratio of 7700 pmol/l per mg/l.h but CT scan of his abdomen was normal with no mass in the adrenals. …