Which result on a 75 g oral glucose tolerance test excludes the diagnosis of acromegaly in a biochemically suspected patient?
- A A rise in IGF-1 during the test
- B Growth hormone level remaining unchanged from baseline
- C Suppression of growth hormone to less than 1 µg/L at any time point ✓
- D Failure of prolactin to suppress below 5 ng/mL
Correct answer: C. Suppression of growth hormone to less than 1 µg/L at any time point
Explanation
Hyperglycemia normally suppresses growth hormone secretion. In acromegaly this suppression is lost. C nadir GH below 1 µg/L during the 75 g oral glucose load excludes active acromegaly with current assays. Random GH levels are uninterpretable because secretion is pulsatile, and IGF-1, though the best single screening test, is not interpreted dynamically during the tolerance test.
Reference: Williams Textbook of Endocrinology, 14th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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