What is the lab workup of an adrenal mass?
Up to 20% of adrenal incidentalomas are found to be biochemically hyperfunctional and should be resected. Therefore, patients should be screened for hypercortisolism, hyperaldosteronism (if hypertensive), and pheochromocytoma with the following tests:
• 1 mg overnight dexamethasone suppression test (8:00 am cortisol):
• ≦ 1.8 mcg/dL—excludes autonomous cortisol secretion
• 1.9–4.9 mcg/dL—evidence of possible autonomous cortisol secretion
• ≧ 5 mcg/dL—evidence of autonomous cortisol secretion
• Only in patients with concomitant hypertension or unexplained hypokalemia—plasma aldosterone concentration (PAC) to plasma renin activity (PRA) ratio (PAC/PRA)—suggestive of aldosteronoma if PAC > 15 ng/dL and PAC/PRA > 20.
• 24-hour urine metanephrines and catecholamines or plasma metanephrines and normetanephrines—diagnostic of pheochromocytoma if ≧ 3-fold above upper limit of normal.
Routine screening for excess androgens or estrogens is not included in the screening algorithm because sex hormone–secreting adrenal tumors are rare and usually clinically apparent.