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Phaeochromocytoma
Phaeochromocytoma is diagnosed first in the laboratory (plasma free or urinary metanephrines) and only then by imaging; before surgery alpha receptors are blocked first for 7–14 days, and a beta-blocker is never started alone.
Why it matters in the exam
The classic question presents attacks of headache, sweating and palpitations with hypertension (paroxysmal or sustained), sometimes with hyperglycaemia, and sometimes an attack set off by anaesthesia, surgery or a beta-blocker. Screening starts with free metanephrines in plasma or fractionated metanephrines in a 24-hour urine collection; a value 3–4 times the upper limit is highly suspicious. Only after biochemical confirmation is CT or MRI of the abdomen done, and with suspected metastases or an extra-adrenal site — functional imaging (Ga-68 DOTATATE PET or MIBG).
Preparation for surgery is almost always tested: alpha blockade (phenoxybenzamine or doxazosin) for 7–14 days, with a high-salt diet and fluids, and only after alpha blockade may a beta-blocker be added for tachycardia. A beta-blocker alone causes unopposed alpha stimulation and a hypertensive crisis. Because a high proportion of patients carry an inherited mutation (MEN2, VHL, NF1, SDH), genetic counselling and testing are recommended for every patient. A hypertensive crisis is treated with intravenous phentolamine. After removal, low blood pressure and hypoglycaemia may occur. Remember too that an incidental adrenal mass always needs metanephrine testing before any biopsy or surgery, because biopsy or handling of an undiagnosed phaeochromocytoma can trigger a life-threatening crisis.
Key points
- Plasma or urinary metanephrines first, imaging afterwards.
- A value 3–4 times normal is highly suspicious.
- Alpha first for 7–14 days, beta only after it.
- Genetic testing for every patient.
- Crisis: intravenous phentolamine.
Summary table
| Step | Test / finding | Action | Exam note |
|---|---|---|---|
| Suspicion | Headache, sweating, palpitations, hypertension | Plasma free metanephrines or 24-hour urinary metanephrines | 3–4 times normal is highly suspicious |
| Localisation | After biochemical confirmation | CT or MRI of the abdomen | Never start with imaging |
| Extra-adrenal or metastatic | Clinical suspicion | Ga-68 DOTATATE PET or MIBG | Paraganglioma |
| Surgical preparation | Alpha first | Phenoxybenzamine or doxazosin for 7–14 days, salt and fluids | Beta only after alpha |
| Genetics | Every patient | Genetic testing | MEN2, VHL, NF1, SDH |
| Hypertensive crisis | Severe hypertension, tachycardia | Intravenous phentolamine | After removal: low blood pressure and hypoglycaemia |
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Sources
- Endocrine Society Clinical Practice Guideline: Pheochromocytoma and Paraganglioma, 2014 — Biochemical testing, imaging, preoperative blockade and genetic testing
- Harrison's Principles of Internal Medicine, 21st edition (2022) — Pheochromocytoma
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-02. The text may contain errors; when in doubt, check the source.