Primary hyperaldosteronism

Primary hyperaldosteronism is an important cause of hypertension. Its true prevalence is still a matter of debate, since about 10% of hypertensives may have underlying hyperaldosteronism. Primary hyperaldosteronism is due to aldosterone-secreting tumours, bilateral adrenal hyperplasia or, rarely, adrenal carcinoma or genetic causes. There is considerable debate over the optimal screening methods for detecting hyperaldosteronism. The patients who benefit the most from screening are young hypertensives, those with resistant hypertension and patients with serum potassium of less than 3.5 mmol/L, especially in the presence of a high sodium. Various tests are available for screening patients with hypertension for hyperaldosteronism. Serum potassium is an unreliable marker for hyperaldosteronism, although a low value in a patient not taking diuretics should make one suspect the diagnosis. The use of serum potassium as a screening test would miss about a third of cases. Determination of the ratio of plasma aldosterone concentration to plasma renin activity is widely accepted as the test of choice for screening. Tests such as diurnal variations in aldosterone concentration and response to angiotensin II help to demonstrate the autonomy of the aldosterone secretion. Once the diagnosis of hyperaldosteronism is made, further tests such as magnetic resonance imaging or computed tomographic scanning and adrenal vein sampling should be undertaken to determine the aetiology of the hyperaldosteronism. Depending on the findings and the lateralization of the lesion, either surgery or medical therapy may be advised for the patient. Spironolactone would be the drug of choice for medical treatment. Laparoscopic adrenalectomy has become a widely employed method of surgically removing adrenal tumours. Hyperaldosteronism represents one of the few treatable causes of hypertension and a systematic approach is therefore needed to ensure that the few patients with an aldosterone-secreting adrenal adenoma are identified. It is important to identify these patients so that only those patients with proven adenomas are referred for adrenalectomy.