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Difficulty: EasyEndocrinology and Metabolism

Match each classic clinical presentation of an endocrine disorder to the most appropriate initial diagnostic screening test.

  • 52-year-old man with an enlarged jaw, coarse facial features, and recently increased shoe sizeSerum insulin-like growth factor 1 (IGF-1) measurement
  • 28-year-old woman with progressive weight gain, proximal muscle weakness, and wide purple abdominal striaeOvernight low-dose dexamethasone suppression test
  • 44-year-old man with treatment-resistant hypertension and unprovoked hypokalemiaPlasma aldosterone concentration to plasma renin activity ratio
  • 31-year-old woman with episodic headaches, severe diaphoresis, and sudden-onset tachycardiaPlasma free metanephrines measurement

Answer

Acromegaly matches with IGF-1; Cushing syndrome matches with the overnight low-dose dexamethasone suppression test; primary hyperaldosteronism matches with the aldosterone-to-renin ratio; and pheochromocytoma matches with plasma free metanephrines.
Each clinical presentation describes a distinct hyperfunctioning endocrine state that requires a specific initial biochemical screening test. Acromegaly (growth hormone excess) is screened with IGF-1. Cushing syndrome (cortisol excess) is screened with a low-dose dexamethasone suppression test. Primary hyperaldosteronism (mineralocorticoid excess) is screened with an aldosterone-to-renin ratio. Pheochromocytoma (catecholamine excess) is screened with plasma free metanephrines.

Step-by-Step Solution

1
Identify the underlying endocrine syndrome for each clinical presentation.
Patient 1 has acromegaly, Patient 2 has Cushing syndrome, Patient 3 has primary hyperaldosteronism, and Patient 4 has pheochromocytoma.
Recognizing the correct syndrome is necessary to select the appropriate biochemical screening test.
2
Determine the most sensitive initial screening test for each identified disorder.
Acromegaly requires IGF-1; Cushing requires hypercortisolism demonstration (dexamethasone suppression); primary hyperaldosteronism requires aldosterone/renin ratio; pheochromocytoma requires metanephrines.
Initial endocrine workups rely on highly sensitive screening tests before confirmatory testing or imaging is pursued.

Key Concept

Initial diagnostic screening tests for classic adrenal and pituitary hypersecretory syndromes.
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Topics

Endocrinology and Metabolism

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