Management of Adrenal Nodules

Initial Diagnostic Workup

The American Urological Association recommends that all patients with adrenal nodules undergo hormonal evaluation, including a 1 mg overnight dexamethasone suppression test, to screen for autonomous cortisol secretion 1, 4
Plasma free metanephrines or 24-hour urinary metanephrines are required for all nodules with >10 HU on non-contrast CT or any symptoms of catecholamine excess, to rule out pheochromocytoma 1, 3, 4
The aldosterone-to-renin ratio should be measured in patients with hypertension and/or hypokalemia, with a ratio >20 ng/dL per ng/mL/hr indicating primary aldosteronism 1, 4
Serum androgens (DHEA-S, testosterone, 17-OH progesterone) should be measured in patients with suspected adrenocortical carcinoma or clinical virilization signs 2, 4

Non-contrast CT is the first-line imaging modality to measure Hounsfield units (HU) and characterize adrenal nodules 1, 3
Lesions with HU ≤10 are definitively benign and do not require further imaging, unless they are >4 cm in size 1, 5
Lesions with HU >10 require second-line imaging with either washout CT or chemical-shift MRI to further characterize 1

The American Urological Association recommends unilateral adrenalectomy via minimally invasive surgery for functional adrenal masses, including those with clinically apparent Cushing's syndrome, mild autonomous cortisol secretion, pheochromocytomas, and aldosterone-secreting adenomas 2, 7
Surgical resection is mandatory for pheochromocytomas and aldosterone-secreting adenomas, with adrenal vein sampling required before surgery to confirm lateralization 1, 2, 7

Non-functional adenomas <4 cm with HU <10 do not require additional imaging or hormonal testing 1, 5, 7
Lesions ≥4 cm but radiologically benign (HU <10) require repeat imaging in 6-12 months to monitor for growth 7, 5
Indeterminate non-functional masses require shared decision-making between repeat imaging and surgical resection, weighing patient age, comorbidities, and anxiety level 1, 7

Bilateral adrenal masses require separate characterization following the same protocol as unilateral masses, with measurement of serum 17-hydroxyprogesterone to exclude congenital adrenal hyperplasia 4
Young adults, children, and pregnant patients require expedited evaluation, with consideration of low-dose CT or chemical-shift MRI to minimize radiation exposure 7, 5
Patients with extra-adrenal malignancy require closer evaluation and a lower threshold for biopsy, after excluding pheochromocytoma 5

Initial hormonal evaluation should never be skipped, even for benign-appearing lesions, as 5% may harbor subclinical hormone production 3, 5
Biopsy should never be performed before excluding pheochromocytoma, as this can precipitate hypertensive crisis 6, 1
Surgery for functional tumors should never be delayed while pursuing additional imaging, as hormonal excess drives morbidity and mortality 2