When evaluating growth hormone deficiency, what test is used to confirm the diagnosis after an initial screening test?

• A. IGF-1 level
• B. MRI brain
• C. GH stimulation tests
• D. Random GH level

Answer: (C)

Growth hormone is released in bursts, so a random measurement isn’t reliable for diagnosing deficiency. IGF-1 can be useful as a screening marker because it reflects GH activity over time, but it isn’t definitive—IGF-1 can be low for reasons other than GH deficiency and can be normal in some affected individuals. MRI of the brain may show structural issues, but seeing an abnormality doesn’t prove that GH secretion is deficient. To confirm the diagnosis after screening, provocative growth hormone stimulation tests are used. These tests deliberately stimulate GH release (using agents like insulin-induced hypoglycemia, arginine, clonidine, or glucagon) and measure the peak GH level. A peak that fails to reach the defined cutoff supports GH deficiency, providing the functional proof needed to confirm the diagnosis.