Growth hormone secretion is LOWEST during which physiological state?

• A Slow-wave (NREM stage 3) sleep, 60–90 minutes after sleep onset
• B Prolonged fasting after 24 hours
• C Intense aerobic exercise
• D Postprandial hyperglycaemia ✓

Explanation

The largest single daily pulse of GH occurs during slow-wave sleep (first NREM stage 3 episode), driven by a GHRH pulse coinciding with reduced somatostatin tone. GH is also high during fasting (mobilising fat), stress, and exercise. In contrast, postprandial hyperglycaemia causes the lowest GH secretion, since glucose raises somatostatin and suppresses GHRH — the basis of the oral glucose tolerance test used to diagnose acromegaly (failure to suppress GH below 1 ng/mL).

Reference: Guyton & Hall, Textbook of Medical Physiology, 14th ed.

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