What is used as the screening test for growth hormone excess?

• A. IGF-1 (Somatomedin C) test
• B. Insulin Tolerance Test
• C. 100 g OGTT
• D. GHRH infusion test

Answer: (A)

IGF-1 measurement is the best first screen for growth hormone excess because GH secretion is highly pulsatile and can vary a lot from moment to moment. IGF-1, produced by the liver in response to GH, stays relatively stable over the day and reflects the overall, integrated amount of GH activity over time. When IGF-1 is elevated for age, it strongly suggests excess GH production, as seen in conditions like acromegaly.

If IGF-1 is high, the next step is a test that confirms the problem by showing that GH is not being suppressed when glucose is given. In a healthy person, a glucose load should suppress GH, but in GH excess, GH remains detectable. The other tests listed are more about assessing GH reserve or provoking GH release under controlled conditions and are not used as the initial screening test due to their complexity and risks.