Question

A 25 year old young woman has recurrent episodes of headache and sweating. Her mother had renal calculi and died after having a neck mass. Physical examination reveals a thyroid nodule but no clinical sign of thyrotoxicosis. Before performing thyroid surgery, the surgeon should order:

• A. Measurement of thyroid hormones
• B. Serial determinations of serum calcium, phosphorus, protein and alkaline phosphatase
• C. 24 hour urine test for 5-hydroxy-indoleacetic acid excretion
• D. Serial 24 hour test for catecholamines, metanephrines and vanillylmandelic acid excretion

Hint:

The family history fits MEN2A; always rule out phaeochromocytoma before any surgery in such patients.

Answer 1

The Correct Option is D

This case is built from three clues: the patient's own headache and sweating attacks, her thyroid nodule, and her mother's history of renal calculi and death after a neck mass. Together these point to a familial syndrome that combines a thyroid cancer, a parathyroid tumour and an adrenal tumour, and we must decide what to check before thyroid surgery.

1. Measurement of thyroid hormones: this only tells us if the thyroid is overactive or underactive. The patient shows no sign of thyrotoxicosis already, and this test does not protect her on the operating table, so it does not answer the real danger here.
2. Serial calcium, phosphorus, protein and alkaline phosphatase: this checks for a parathyroid problem, which matches the mother's renal calculi, but a missed parathyroid tumour will not kill the patient during anaesthesia. It is useful but not the most urgent step.
3. 24 hour urine 5-hydroxy-indoleacetic acid: this is the screening test for carcinoid tumours, and nothing in the story points to carcinoid disease, so this option is out of place.
4. Serial catecholamines, metanephrines and vanillylmandelic acid: episodic headache and sweating are the hallmark symptoms of a phaeochromocytoma, an adrenal tumour that is part of the same inherited syndrome suggested by the mother's neck mass and renal calculi. An unrecognised phaeochromocytoma can cause a fatal surge in blood pressure the moment anaesthesia or surgery begins.

Because a missed phaeochromocytoma can be fatal on the operating table, it has to be excluded first, using the catecholamine, metanephrine and vanillylmandelic acid test, before the thyroid is touched.

Let's summarize:

• Headache and sweating plus a family pattern of thyroid and parathyroid tumours suggest MEN2A, which also carries phaeochromocytoma.
• Phaeochromocytoma must be screened for and treated before any operation, since it is the one finding that can turn fatal under anaesthesia.

The correct test to order first is the serial catecholamine, metanephrine and vanillylmandelic acid excretion test.