Pragmatic Evaluation of Growth Hormone Stimulation Tests in Short Stature

Area of Science:

• Pediatric Endocrinology
• Diagnostic Testing
• Hormone Assays

Background:

• Short stature is a common concern in pediatric endocrinology, necessitating accurate diagnosis of growth hormone deficiency (GHD).
• Growth hormone stimulation tests (GHSTs) are essential for evaluating GH reserve but can be resource-intensive.
• Optimizing GHST protocols is critical to balance diagnostic accuracy with efficiency.

Purpose of the Study:

• To assess the performance of clonidine stimulation test (CST) and glucagon stimulation test (GST) in diagnosing GHD in children with short stature.
• To evaluate the impact of reducing sampling time points on the false positive rate (FPR) of GHSTs.

Main Methods:

• A single-centre retrospective study of 556 children evaluated for short stature between 2005 and 2020.
• Utilized CST and GST to assess growth hormone (GH) reserve, with GST performed when CST peak GH was 5 to ≤10 ng/mL.
• Analyzed FPR associated with restricting GH sampling to two or three time points.

Main Results:

• The median peak GH level was 5.50 ng/mL on CST and 7.45 ng/mL on GST.
• Restricting sampling to two time points resulted in FPRs of 13.6% for CST and 11.5% for GST.
• Restricting to three time points yielded FPRs of 8.5% for CST and 3.8% for GST.
• An optimal CST peak GH cut-off of 7.79 ng/mL showed 83.8% sensitivity and 89.4% specificity for GHD.

Conclusions:

• Reducing the number of GH sampling points during stimulation tests increases the false positive rate.
• Careful consideration of sampling frequency is necessary to maintain diagnostic accuracy in GHSTs.
• Optimizing GHST protocols can improve the efficiency of diagnosing GHD in children with short stature.