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

Step 1: Understanding the Question:
The patient has headache and sweating attacks, a thyroid nodule, and a mother who had renal calculi and died after a neck mass. Put together, this pattern points to a familial endocrine tumour syndrome, and we need to know what test the surgeon must order before operating on the thyroid.

Step 2: Key Formula or Approach:
This history fits multiple endocrine neoplasia type 2A: medullary thyroid carcinoma (the mother's neck mass), a parathyroid tumour causing hyperparathyroidism (the mother's renal calculi), and a phaeochromocytoma (this patient's headache and sweating attacks). Whenever phaeochromocytoma is even a possibility, it must be ruled out before any surgery, because operating on an unrecognised phaeochromocytoma can trigger a fatal blood pressure crisis under anaesthesia.

Step 3: Detailed Explanation:
Measuring thyroid hormones would only check thyroid function. The patient already has no signs of thyrotoxicosis, and this test does nothing to protect her during surgery, so it is not the priority.
Serial calcium, phosphorus, protein and alkaline phosphatase would work up hyperparathyroidism, which fits the mother's renal calculi, but a missed parathyroid problem does not cause a sudden intra operative crisis the way a missed phaeochromocytoma does. It is not the first, most urgent step.
24 hour urine 5-hydroxy-indoleacetic acid screens for carcinoid tumours, which are not suggested anywhere in this history, so this option does not fit the case.
Serial 24 hour catecholamines, metanephrines and vanillylmandelic acid screen for phaeochromocytoma. Her headache and sweating attacks are classic phaeochromocytoma symptoms, and this tumour is part of the same familial syndrome as her mother's neck mass. If this test is positive, the patient needs alpha blockade before any operation, thyroid included, to avoid a catecholamine driven hypertensive crisis during anaesthesia.

Step 4: Final Answer:
Phaeochromocytoma must always be excluded first in this setting, so the correct order is the catecholamine, metanephrine and vanillylmandelic acid test, option 4.