Growth hormone (GH) provocative testing frequently does not reflect endogenous GH secretion

Area of Science:

• Pediatric Endocrinology
• Growth Hormone Physiology
• Diagnostic Testing

Background:

• Growth hormone (GH) deficiency and GH neurosecretory dysfunction (GHND) are key concerns in pediatric short stature.
• Accurate assessment of GH secretion is crucial for diagnosis and treatment.
• Current diagnostic methods include provocative testing and 24-hour GH sampling.

Purpose of the Study:

• To evaluate the correlation between provocative GH testing and endogenous 24-hour GH secretion in children.
• To compare GH secretion patterns in GH-deficient children, GHND children, and control groups.
• To determine the reliability of shorter sampling intervals for assessing GH secretion.

Main Methods:

• Studied 73 children: classical GH deficiency, GHND, intrinsic short stature, and normal stature controls.
• Administered provocative GH tests (arginine, L-dopa, insulin hypoglycemia, clonidine).
• Conducted 24-hour GH sampling every 20 minutes, with analysis of 12-hour and 6-hour intervals.

Main Results:

• GH-deficient children showed significantly lower peak GH response to provocative tests compared to GHND and short controls.
• Mean 24-hour GH concentrations were reduced in GH-deficient and GHND children versus controls.
• Peak GH levels from provocative tests poorly correlated with mean 24-hour GH concentrations across all groups.

Conclusions:

• Provocative GH testing frequently does not correlate with endogenous GH secretion.
• 24-hour GH sampling provides a more reliable measure of GH secretion than provocative tests.
• Shorter sampling intervals (6-12 hours) show more overlap than 24-hour data for individual children.