A man has hypotension, hyponatraemia, hyperkalaemia and skin pigmentation. Which test confirms the likely diagnosis?
Answer and explanation
Correct answer: B. A short corticotrophin (ACTH) stimulation test showing a failed cortisol response
- Step 1: Low sodium, high potassium, low blood pressure and pigmentation indicate primary adrenal insufficiency. Step 2. The synacthen test shows that the adrenal cortex cannot raise cortisol. Answer: ACTH stimulation test. Why not the others: Dexamethasone suppression tests Cushing syndrome. Metanephrines test for phaeochromocytoma. Water deprivation tests diabetes insipidus.
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