A 44-year-old man has progressive shoe size increase, frontal bossing, and new hypertension. Which single blood test is the most useful screening investigation for acromegaly in this patient?

• A Random growth hormone level
• B Morning ACTH
• C Fasting prolactin
• D Serum IGF-1 ✓

Explanation

IGF-1 is produced by the liver under growth hormone drive, has a long half-life, and reflects integrated GH secretion over the day, unlike random GH which pulses widely and can be elevated normally after exercise or stress. An age- and sex-matched elevated IGF-1 effectively confirms GH excess and prompts pituitary MRI and confirmatory oral glucose suppression testing. Random GH is unreliable precisely because secretion is pulsatile.

Reference: Williams Textbook of Endocrinology, 14th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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