What tests do we order to assess for an adrenal tumor?

Assessment of Adrenal Tumors

All patients with adrenal tumors require both comprehensive hormonal evaluation and dedicated imaging with an adrenal protocol CT or MRI to determine malignancy risk and functional status. 1, 2

Mandatory Hormonal Testing (Required for ALL Patients)

Cortisol Assessment

• Perform 1 mg overnight dexamethasone suppression test (administer 1 mg dexamethasone at 11 PM, measure serum cortisol at 8 AM) as the preferred screening method 2, 3
• Measure plasma ACTH levels as part of cortisol assessment 2, 3
• Interpretation: serum cortisol ≤50 nmol/L excludes hypersecretion; 51-138 nmol/L suggests possible autonomous secretion; >138 nmol/L indicates cortisol excess 2
• Consider 24-hour urinary free cortisol for additional confirmation 2

Aldosterone Assessment

• Measure aldosterone-to-renin ratio in ALL patients with hypertension and/or hypokalemia 2, 3
• Check serum potassium levels 2, 3
• An aldosterone/renin ratio >20 ng/dL per ng/mL/hr has excellent sensitivity and specificity for primary aldosteronism 2

Catecholamine Assessment

• Test plasma free metanephrines or 24-hour urinary fractionated metanephrines in ALL patients with adrenal masses >10 HU on non-contrast CT or any symptoms of catecholamine excess 2, 3
• Include normetanephrine and methoxytyramine measurements when available 2

Androgen Assessment (Specific Indications)

• Measure DHEA-S, 17-OH-progesterone, androstenedione, testosterone, and 17-beta-estradiol in patients with:
  • Signs of virilization 2, 3
  • Suspected adrenocortical carcinoma 2, 3
  • Bilateral adrenal masses 2, 3

Imaging Studies

First-Line Imaging

• Obtain non-contrast CT as the initial imaging modality to assess Hounsfield units (HU) 1, 2
• CT is less expensive than MRI and should be the first choice 2
• HU <10 on unenhanced CT strongly suggests benign adenoma 1, 2

Second-Line Imaging (When Initial CT is Indeterminate)

• Perform contrast-enhanced CT with 15-minute delayed washout imaging when initial non-contrast CT shows HU >10 1, 2

• 60% washout at 15 minutes indicates likely benign tumor; <60% suggests possible malignancy 1, 2

• Chemical-shift MRI showing signal intensity loss on opposed-phase imaging is an alternative to characterize lipid-rich adenomas 1, 2

Special Imaging Considerations

• Use MRI over CT when pheochromocytoma is suspected to avoid hypertensive crisis from intravenous contrast 2
• FDG-PET is useful for distinguishing potentially malignant lesions from benign tumors in radiologically indeterminate masses 2

Adrenal Protocol Imaging Requirements

The adrenal protocol must assess: 1

• Size
• Heterogeneity
• Lipid content (MRI) or contrast washout (CT)
• Margin characteristics

Additional Laboratory Tests

• Obtain basic metabolic panel to assess electrolyte abnormalities 2, 3
• Perform complete blood count to identify hematologic abnormalities affecting surgical planning 2, 3

Critical Pitfalls to Avoid

• NEVER perform adrenal biopsy without first excluding pheochromocytoma - biopsy of undiagnosed pheochromocytoma triggers life-threatening hypertensive crisis 1, 2, 3
• Do not skip hormonal testing even in apparently non-functioning tumors - subtle hormone production impacts surgical management and perioperative care 2, 3
• Radiological appearance cannot reliably predict hormone secretion status 2, 3
• Fine needle biopsy of suspected adrenocortical carcinoma is almost never justified due to risk of tumor spill 2
• Adrenal biopsy should only be performed in patients with known extra-adrenal malignancy and suspected adrenal metastasis, and only after pheochromocytoma is excluded 1

When to Involve Multidisciplinary Team

Obtain multidisciplinary review by endocrinologists, surgeons, and radiologists when: 1

• Imaging is not consistent with a benign lesion
• Evidence of hormone hypersecretion exists
• Tumor has grown significantly during follow-up
• Adrenal surgery is being considered