What labs should be obtained to evaluate an adrenal mass?

From the Guidelines

To evaluate an adrenal mass, initial laboratory evaluation should include plasma free metanephrines or 24-hour urinary metanephrines and catecholamines to rule out pheochromocytoma, 1mg overnight dexamethasone suppression test or late-night salivary cortisol to assess for Cushing's syndrome, and plasma aldosterone concentration to plasma renin activity ratio to screen for primary aldosteronism, as recommended by the most recent guidelines 1.

Key Laboratory Tests

• Plasma free metanephrines or 24-hour urinary metanephrines and catecholamines to rule out pheochromocytoma
• 1mg overnight dexamethasone suppression test or late-night salivary cortisol to assess for Cushing's syndrome
• Plasma aldosterone concentration to plasma renin activity ratio to screen for primary aldosteronism
• Serum potassium in patients with hypertension
• Dehydroepiandrosterone sulfate (DHEAS) and testosterone levels in females with signs of androgen excess
• Estradiol levels in males with feminization

Rationale

These tests are essential because even radiographically benign-appearing adrenal masses can secrete hormones that cause significant health problems, as highlighted in the guidelines 1. Identifying a functional adrenal tumor is critical as it typically requires surgical removal, while non-functional tumors may be observed if they meet certain size criteria. Laboratory evaluation should be performed prior to any invasive procedures to avoid precipitating a hypertensive crisis in cases of pheochromocytoma. The guidelines also emphasize the importance of screening for cortisol excess in all patients with adrenal incidentalomas, given the imperfect nature of imaging techniques 1.

From the Research

Evaluation of Adrenal Mass

To evaluate an adrenal mass, several laboratory tests are recommended to assess for hormonal excess and malignant potential. The following labs should be obtained:

• Blood tests for:
  • Electrolyte panel to evaluate for hyperaldosteronism 2
  • Adrenocorticotropic hormone (ACTH) level to evaluate for Cushing's syndrome 3, 4
  • Dehydroepiandrosterone sulfate (DHEAS) level to evaluate for adrenal hormone excess 3
  • Aldosterone-renin ratio to evaluate for primary aldosteronism 2
• Urine tests for:
  • 24-hour urinary free cortisol (UFC) excretion to evaluate for Cushing's syndrome 2
  • Urinary metanephrines and normetanephrines to evaluate for pheochromocytoma 2
• Additional tests:
  • Low-dose dexamethasone suppression test to evaluate for Cushing's syndrome 4, 2, 5
  • Late evening salivary cortisol to evaluate for Cushing's syndrome 2

Biochemical Testing

Biochemical testing is essential to identify hormonally active lesions and rule out malignancy. The tests listed above can help identify excess hormone production, which can guide further management and treatment. For example, a low-dose dexamethasone suppression test can help diagnose subclinical Cushing's syndrome, which is often associated with primary aldosteronism 4, 5.

Clinical Assessment

A thorough clinical assessment is also crucial in evaluating an adrenal mass. This includes assessing for signs and symptoms of hormonal excess, such as hypertension, hypokalemia, and Cushingoid features. The clinical assessment, combined with imaging characteristics and biochemical testing, can help guide the management of the adrenal mass 3, 6.