Endocrine Abstracts

Introduction: Vitamin D and growth hormone/insulin-like growth factor-1 (GH/IGF-1) axis are reported to interplay at both endocrine and paracrine levels, with a positive correlation between IGF-1 and 25-hydroxyvitamin D (25(OH)D) in healthy subjects. Hyposomatotropism is among the conditions predisposing to lower vitamin D status due to several direct and indirect mechanisms. Thus, the aim of our study was to evaluate vitamin D status in a representative sample of adults with GH deficiency (GHD) and to investigate the association between serum 25(OH)D and age, gender and onset of hyposomatotropism.

Methods: This cross-sectional study included 129 adults (aged 42.1±16.6 years, 70 males) diagnosed with GHD (41.9% with childhood-onset GHD (COGHD)) in the Clinical Centre of Endocrinology in Sofia, Bulgaria. Total serum 25(OH)D was the vitamin D metabolite used to assess vitamin D status and was measured by electro-chemiluminescence binding assay. Vitamin D status and GHD were defined according to the Endocrine Society Clinical Practice Guideline recommendations.

Results: Major part of the patients was diagnosed with vitamin D deficiency (79.1%, n=102) and another 14.7% (n=19) had vitamin D insufficiency. 25(OH)D levels >30 ng/ml were found in only 6.2% (n=8) of the subjects. Mean 25(OH)D levels (15.1±7.6 ng/ml) did not differ between men and women (15.7±7.2 vs. 14.5±8.1 ng/ml, P=0.387) and correlated negatively and weakly with age (r=−0.256; P=0.003). In the AOGHD subgroup, however, mean serum 25(OH)D was significantly lower compared with COGHD participants (14.0±7.2 vs.16.8±8.0 ng/ml, P=0.039).

Conclusion: Data from our study demonstrated considerably high prevalence of hypovitaminosis D in GHD adults, with lower 25(OH)D concentrations among the subgroup with AOGHD. Therefore, 25(OH)D testing is highly recommended in patients with hyposomatotropism. Normalization of vitamin D status might have beneficial effects in GHD subjects, especially considering the additive effects of vitamin D and GH replacement.