What is the best method to diagnose an adrenal adenoma?

From the Guidelines

The best approach to diagnose an adrenal adenoma involves a comprehensive work-up including a focused history and physical examination, imaging studies, and hormonal testing, as recommended by the most recent guidelines 1. When evaluating an adrenal mass, it's essential to determine if it's functioning (hormone-producing) or non-functioning. This requires a comprehensive hormonal workup including plasma free metanephrines to rule out pheochromocytoma, aldosterone-to-renin ratio for primary aldosteronism, and overnight dexamethasone suppression test for Cushing's syndrome.

Key Diagnostic Steps

• A focused history and physical examination aimed at identifying signs/symptoms of adrenal hormone excess, adrenal malignancy, and/or extra-adrenal malignancy should be performed 1.
• Non-contrast CT is recommended as the first-line imaging to distinguish benign lesions from those which require further radiologic investigation 1.
• For patients with indeterminate adrenal masses on non-contrast CT, second-line imaging with either washout CT or chemical-shift MRI should be considered 1.
• Adrenal mass biopsy should not be performed routinely for the work-up of an adrenal incidentaloma, except in specific cases where malignancy is suspected 1.
• All patients with adrenal incidentalomas should be screened for autonomous cortisol secretion, and 1 mg dexamethasone suppression testing is the preferred screening test 1.
• Patients with adrenal incidentalomas and hypertension and/or hypokalemia should be screened for primary aldosteronism with an aldosterone-to-renin ratio, and adrenal vein sampling is recommended prior to offering adrenalectomy in patients with primary aldosteronism 1.

Imaging and Hormonal Testing

• CT scan with contrast is the preferred imaging modality, as it can characterize adrenal masses with high sensitivity and specificity.
• MRI serves as an excellent alternative, particularly for patients who cannot receive contrast or when further tissue characterization is needed.
• Size criteria are important - lesions smaller than 4 cm with benign imaging characteristics (homogeneous, low attenuation <10 Hounsfield units on non-contrast CT) are typically adenomas.
• Larger or suspicious lesions may require follow-up imaging or biopsy.

Management

• Adrenalectomy should be performed for patients with unilateral aldosterone-secreting adrenal masses and pheochromocytomas, and minimally-invasive surgery (MIS) should be performed when feasible for these procedures 1.
• Patients with benign non-functional adenomas <4 cm, myelolipomas, and other small masses containing macroscopic fat detected on the initial work-up for an adrenal incidentaloma do not require further follow-up imaging or functional testing 1.
• Shared decision-making between patients and their clinicians should be used for the management of indeterminate non-functional adrenal lesions, and management options include repeat imaging in 3-6 months versus surgical resection 1.

From the FDA Drug Label

1 INDICATIONS AND USAGE Metopirone is indicated, in combination with other diagnostic tests, for the diagnosis of adrenal insufficiency in adult and pediatric patients.

The FDA drug label does not answer the question.

From the Research

Diagnostic Approaches for Adrenal Adenoma

• The diagnosis of adrenal adenoma involves a combination of hormone tests to detect adrenal hyperfunction and imaging studies to assess the nature of the adrenal lesion 2.
• Imaging techniques such as CT scans, MRI, and PET/CT can be used to characterize adrenal adenomas, with CT contrast washout analysis being a useful tool for differentiating adenomas from other adrenal lesions 2, 3.
• Adrenal vein sampling (AVS) is a valuable diagnostic tool for confirming lateralization of aldosterone secretion in patients with primary hyperaldosteronism, particularly when imaging studies are inconclusive 4, 5.

Role of Imaging in Diagnosing Adrenal Adenoma

• Adrenal adenomas can manifest various imaging features on CT, MRI, and PET/CT, and the choice of imaging modality depends on the specific clinical scenario 3.
• The size of the adrenal adenoma can be an important factor in determining the likelihood of autonomous cortisol secretion and metabolic derangements, with larger adenomas being more likely to be associated with these conditions 6.

Laboratory Tests and Diagnostic Criteria

• Hormone tests such as plasma renin activity and aldosterone-to-renin ratio can be used to screen for primary hyperaldosteronism, while dexamethasone suppression tests can help confirm the diagnosis of autonomous cortisol secretion 4, 6.
• The cortisol-corrected aldosterone concentration and aldosterone-to-renin ratio can be used to diagnose primary aldosteronism, with adrenal vein sampling being used to confirm lateralization of aldosterone secretion 5.