CLONIDINE STIMULATION TEST FOR GH DEFICIENCY: A NEW LOOK AT SAMPLE TIMING

Area of Science:

• Endocrinology
• Pediatric Endocrinology
• Diagnostic Testing

Background:

• The glucagon stimulation test (GST) uses peak growth hormone (GH) timing to assess secretion.
• The utility of peak GH timing in the clonidine stimulation test (CST) remains unexamined.
• Previous studies suggest omitting the 120-minute sample in CST.

Purpose of the Study:

• To evaluate the significance and utility of peak GH timing in the CST.
• To determine if shortening the CST impacts diagnostic accuracy.

Main Methods:

• Analysis of 250 consecutive CST results from a single center.
• Comparison of CST peak timing with confirmatory GST results.
• Assessment of GH sufficiency or deficiency based on test outcomes.

Main Results:

• Peak GH in CST typically occurred at 30, 60, and 90 minutes (91.6%).
• GH sufficient tests showed typical peak timing more often (85.15%) than deficient tests (68%).
• Peak timing in CST did not predict the final diagnostic result or correlate with confirmatory GST.

Conclusions:

• GH peak timing is not a useful factor for interpreting CST results.
• The CST is effective when shortened to 90 minutes, with minimal impact on outcomes (0.4% change).