Evaluation of the Relationship Between Peak Growth Hormone Response to Growth Hormone Stimulation Tests and Body Mass Index

Abstract

Objective: A contrary relationship between body mass index (BMI) and growth hormone (GH) secretion has been demonstrated in adults. BMI-specific cutoff levels are suggested for identifying growth hormone deficiency (GHD) in adulthood. However, specific values for BMI and growth hormone stimulation test responses in the childhood age group are not certain. In this research, our purpose was to investigate the relationship between GH peak response and BMI in children who underwent GHST with a pre-diagnosis of GHD. Material and Methods: This was a retrospective study of stimulative GH testing with clonidine and L-dopa performed in 150 children 2–18 year-old with short stature (< -2 SDS) in the Pediatric Endocrinology Unit at Bakırçay University Çiğli Training and Research Hospital from the years of 2018 to 2023. Anthropometric measurements, insulin-like growth factor-1 (IGF-I) and IGFBP- 3 levels, especially peak-stimulated GH, were evaluated. Results: A total of 150 patients [98 boys (65.3%) and 52 girls (34.7%)] were included in the study. The mean age of the individuals during testing was 10.26 ± 3.37 years, mean height standard deviation score (SDS) was -2.64 ± 0.89, mean weight SDS was -1.85 ± 1.01 and mean body mass index (BMI) SDS was -0.47 ± 1.07. Ninety-two of the patients (63%) were prepubertal. The mean value for maximum growth hormone serum level (GHmax) clonidine collected during the growth hormone stimulation test was 4.46 ± 2.83 ng/mL, while the mean value in L-dopa test was 3.29 ± 2.57 ng/mL. There was no statistical distinction in terms of both test responses. The correlation between peak GH and BMI-SDS, in terms of clonidine and L-dopa tests, was significantly negative [β = -0.257 (p = 0.010), β = -0.283 (p = 0.004), respectively]. Age, gender and puberty were not significantly associated with peak GH value. In terms of L-dopa peak GH level, the GH level in group 4 (>1 SDS) was revealed to be statistically lower than that in group 1 (< -1 SDS), nevertheless, similar relationship was not detected for clonidine. Conclusion: In our study, a negative correlation was found between GHmax and BMI-SDS in terms of clonidine and L-dopa tests. Therefore, keeping BMI-SDS in mind when evaluating growth hormone stimulation tests performed in short children may be guiding. Still, future studies are needed to make it a determining factor when deciding on treatment.