Behind the Knife ABSITE 2026: Adrenal Gland Review

Adrenal Gland Anatomy and Physiology

• ⚕️ The adrenal gland's vascular supply includes the superior adrenal artery (from the phrenic artery), middle adrenal artery (from the aorta), and inferior adrenal artery (from the renal artery).
• 💧 Venous outflow is via the left adrenal vein into the left renal vein and the right adrenal vein into the IVC.
• 🧠 The adrenal cortex consists of the zona glomerulosa (aldosterone), zona fasciculata (glucocorticoids), and zona reticularis (androgens/estrogens), following the "salt, sugar, sex" mnemonic.
• ⚡ The adrenal medulla contains chromaffin cells that produce epinephrine and norepinephrine.

Adrenal Incidentalomas

• 📈 Adrenal incidentalomas are found in 1-2% of CT scans, often discovered during trauma imaging.
• 🔍 Workup involves evaluating for concerning imaging features (size > 4 cm, > 10 Hounsfield Units on non-contrast CT, < 30% washout) and assessing for functionality.
• 🧪 Functional workup includes urine metanephrines, VMA, catecholamines, DHEA sulfate, and a low-dose dexamethasone suppression test, alongside serum potassium, renin, and aldosterone.

Adrenal Pathologies

• 🧬 Congenital Adrenal Hyperplasia (CAH) results from enzyme deficiencies (21, 11 beta, or 17 hydroxylase), leading to hormonal imbalances like increased testosterone and altered aldosterone/cortisol levels.
• 🫀 Hyperaldosteronism (Conn syndrome) presents with hypertension, elevated sodium, and low potassium, distinguished by low renin (primary) vs. high renin (secondary) and a high aldosterone-to-renin ratio.
• 📉 Hypocortisolism (Addison's disease) can present chronically (fatigue, weight loss) or acutely (adrenal crisis with hypotension); diagnosis involves AM cortisol, ACTH stimulation tests, and ACTH levels to differentiate primary vs. secondary causes.
• 🌕 Cushing syndrome results from excess cortisol, most commonly due to exogenous steroid use; workup involves 24-hour urine cortisol, late-night serum cortisol, and ACTH levels to identify adrenal, pituitary, or ectopic sources.

Functional Adrenal Tumors

• 💥 Pheochromocytomas are neuroendocrine tumors producing catecholamines, characterized by hypertension, palpitations, and a sense of doom; the "rule of 10" applies (10% malignant, bilateral, familial, extra-adrenal, in children).
• 🧪 Diagnosis of pheochromocytoma involves plasma-free metanephrines and 24-hour urine metanephrines, with imaging (CT, MRI, MIBG scan) to localize the tumor, often found near the aortic bifurcation for extra-adrenal types.
• 💊 Preoperative management for pheochromocytoma includes alpha-blockade (phenoxybenzamine or prazosin) followed by beta-blockade to prevent hypertensive crisis during surgery.
• 📈 Adrenocortical carcinoma is a rare, aggressive malignancy often presenting with Cushing syndrome, virilization, or hypertension; management involves radical adrenalectomy, debulking, and potentially mitotane and radiotherapy.

Benign and Metastatic Adrenal Lesions

• 🦴 Adrenal myelolipomas are benign tumors of fat and bone marrow, often diagnosed on CT and typically observed unless symptomatic or very large.
• 🫁 Metastases to the adrenal gland most commonly originate from lung cancer, and biopsy is indicated if metastasis is suspected after ruling out a pheochromocytoma.
• ⚠️ Laparoscopic resection of adrenal masses invading the abdominal sidewall should be converted to an open procedure due to the theoretical risk of spread for adrenocortical carcinoma.