Case detection of primary aldosteronism using the aldosterone-renin ratio (ARR): A three year experience in a tertiary hospital.

BACKGROUND: Primary aldosteronism is a common, treatable and potentially curable cause of hypertension. It is a much more common cause of hypertension than was previously thought, and aldosterone excess may have deleterious effects on the cardiovascular system that are at least partly independent of blood pressure elevation. Plasma aldosterone-renin ratio is currently the most reliable available screening test for primary aldosteronism.

OBJECTIVE: To determine the cases of primary aldosteronism using aldosterone-renin ratio as screening tool.

METHODOLOGY: This is a retrospective, descriptive study. Seventy-two charts of patients with plasma aldosterone and renin determination done were reviewed.

RESULTS: Forty-three patients had positive aldosterone-renin ratio (ARR≥30). Only 23 submitted to a confirmatory test. Eighteen were females. The mean age was 40 y.o; the mean duration of onset of hypertension was 5 years prior to consult. Mean systolic and diastolic BP were 195mmHg and 100mmHg, respectively. All were hypokalemic. Fourteen showed a positive result in confirmatory saline infusion test. Computed tomography was done. Ten had unilateral adrenal nodule, 2 had adrenal limb thickening and 2 had bilateral adrenal lesions. Those with bilateral lesions underwent bilateral adrenal vein sampling, but no lateralization was demonstrated. They were given medical therapy, as well as the other 2 with adrenal limb thickening. The ten patients with unilateral adrenal lesions underwent unilateral adrenalectomy. Serum potassium normalized postoperatively; blood pressure improved but 3 patients continued to maintain on antihypertensive medication after surgery.

CONCLUSIONS: Primary aldosteronism is a potentially curable disease. Hypokalemia and blood pressure improve upon treatment. Case detection using plasma aldosterone-renin ratio be done in high risk group. Confirmatory test must be pursued in those with positive ratio. CT scan is helpful in detecting the lesion and adrenal vein sampling be done to lateralize the hyperfunctioning adrenal.