What is the management approach for a hypermetabolic focus in the left adrenal gland?

Management of Hypermetabolic Focus in Left Adrenal Gland

A hypermetabolic focus in the left adrenal gland requires immediate comprehensive hormonal evaluation followed by characterization imaging to determine if this represents a functional tumor (particularly pheochromocytoma) or other pathology, with surgical resection indicated for functional lesions. 1

Immediate Diagnostic Priorities

Critical First Step: Rule Out Pheochromocytoma

• Measure plasma free metanephrines or 24-hour urinary metanephrines immediately before any further intervention, as hypermetabolic activity on imaging (PET or MIBG scan) strongly suggests catecholamine-secreting tumor. 1, 2
• Levels >2X upper limit of normal confirm pheochromocytoma. 1
• Never perform biopsy before excluding pheochromocytoma, as this can precipitate life-threatening hypertensive crisis. 2

Complete Hormonal Workup Required

• 1 mg overnight dexamethasone suppression test to screen for autonomous cortisol secretion (cortisol >138 nmol/L indicates hypersecretion). 1, 2
• Aldosterone-to-renin ratio if patient has hypertension or hypokalemia (ratio >20 ng/dL per ng/mL/hr indicates primary aldosteronism). 1, 2
• Serum androgens (DHEA-S, testosterone, 17-OH progesterone) if adrenocortical carcinoma suspected or virilization signs present. 1, 2

Imaging Characterization Algorithm

First-Line Imaging

• Non-contrast CT scan to measure Hounsfield Units (HU) and assess lesion characteristics. 1
• Lesions with HU ≤10 are definitively benign (0% risk of adrenocortical carcinoma). 1
• Lesions with HU >10 require second-line imaging with washout CT or chemical-shift MRI. 2

Correlation with Metabolic Imaging

• Hypermetabolic activity on PET or MIBG scan combined with elevated metanephrines strongly indicates pheochromocytoma or adrenal medullary hyperplasia. 3
• Diffuse bilateral uptake suggests adrenal medullary hyperplasia rather than discrete pheochromocytoma. 3

Management Based on Functional Status

If Pheochromocytoma Confirmed

• Surgical resection is mandatory via minimally-invasive adrenalectomy when feasible. 1, 2
• Preoperative alpha-blockade with phenoxybenzamine starting at 10 mg twice daily, increased every other day to 20-40 mg 2-3 times daily until blood pressure controlled. 4
• Add beta-blocker only after adequate alpha-blockade if tachycardia excessive. 4

If Cortisol-Secreting Lesion with Clinical Cushing's

• Unilateral adrenalectomy of affected gland via minimally-invasive surgery. 1

If Mild Autonomous Cortisol Secretion (MACS)

• Consider adrenalectomy for younger patients with progressive metabolic comorbidities (diabetes, hypertension, cardiovascular events, vertebral fractures) attributable to cortisol excess after shared decision-making. 1, 5
• Annual clinical screening for new/worsening comorbidities if surgery declined. 1

If Aldosterone-Secreting Adenoma

• Adrenal vein sampling required for lateralization before surgery. 2, 6
• Unilateral adrenalectomy via minimally-invasive approach for confirmed unilateral disease. 1, 2

Multidisciplinary Review Threshold

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

• Imaging not consistent with benign lesion
• Evidence of hormone hypersecretion confirmed
• Tumor growth documented on follow-up
• Adrenal surgery being considered

Key Clinical Pitfalls to Avoid

• Never skip hormonal evaluation even if lesion appears benign radiologically, as 5% harbor subclinical hormone production. 2
• Never biopsy before excluding pheochromocytoma to avoid hypertensive crisis. 2
• Never delay surgery for functional tumors while pursuing additional imaging, as hormonal excess drives morbidity and mortality. 2
• Hypermetabolic activity on functional imaging (PET/MIBG) with HU >10 on CT creates high suspicion for pheochromocytoma or adrenal medullary hyperplasia requiring urgent biochemical confirmation. 3