Hypertension: strategies for laboratory diagnosis.

Although surgically correctable causes account for relatively few cases of hypertension, laboratory investigation is warranted if clinical clues are present. Pheochromocytoma, which triggers hypertension by producing excess catecholamines, can be identified by detecting metabolites of these substances in urine. An abnormal intravenous pyelogram suggests renovascular hypertension, but for definitive diagnosis, bilateral renal vein renin measurements are necessary. In primary aldosteronism, with its characteristic hypokalemia, serum potassium determination remains the most feasible, if not the most accurate, detection method.