Growth Hormone Stimulation Test: Results and Predictive Factors

Objective: Growth hormone stimulation test (GHST) has become a standard test in the assessment of short stature. Our objectives are to determine if there are predictive factors for post stimulation growth hormone (GH) level and to assess the correlation between the peak GH level and the first year response to treatment.
Method: It is a descriptive retrospective study of 113 subjects with short stature who were admitted to Tawam Hospital, UAE, from January 2010 to May 2016 for GHST, excluding Turner syndrome, small for gestational age or chronic renal insufficiency. The subject’s baseline characteristics as well as labs and imaging were retrieved. All statistical analysis was done using R software version 3.0.3.
Results: Weight (Wt) SDS and insulin like growth factor-1 (IGF-I) were constant significant factors across the different cut-off levels of 10, 7 and 5 ng/ml, with all P vales ≤ 0.01. There was +0.4 (± 0.34) change in the height SDS by the end of first year of GH treatment (P<0.0001) with a significant negative correlation with IGF-1 level (P=0.012) and positive correlation with insulin like growth factor binding protein -3 (IGF-BP3) level (P=0.039).
Conclusion: The normal Wt and low IGF-1 level were constant risk factors for low GH response regardless of the cut-off peak stimulated GH level used, which could be considered as potential predicators of GH status. On the other hand, low IGF-1 and normal IGF-BP3 can predict the GH response during the first year of treatment.