Endocrine Abstracts

Introduction: Growth hormone (GH) is not only important for growth during childhood. Also, for (young) adults, growth hormone is important for bone mass, muscle strength and metabolism. GH deficiency (GHD) is a condition that can cause a broad range of adult health issues, if left untreated. Therefore on one hand, it is important to confirm and treat GHD after transfer to adult care. On the other hand, the personal and financial burden of unnecessary growth hormone injections should be avoided. For this reason, adolescents with childhood onset GHD should be retested after reaching adult height.

Case presentation: We present a case of a 19-year-old non-obese Caucasian male who, due to isolated GHD, was treated with GH during childhood (needle-free system). After reaching adult height, GH treatment was stopped and the patient was re-tested for GHD after a washout period. GH peak after stimulation with GHRH-arginine was 5.5 μg/l, which is considered persistent GHD. When the paediatric endocrinologist wanted to restart GH, patient refused, as he had a fear of needles and the needle-free GH was no longer available. Therefore the shared decision was made that restarting GH would be evaluated after transfer to adult endocrinology. At the first appointment at the adult outpatient clinic it was noted that, apart from low serum IGF-1 levels, 25-OH vitamin D level was extremely low (<10 nmol/l). Knowing that the promoter of the GH1 gene contains a vitamin D-responsive element, it was hypothesized that the low vitamin D levels might have contributed to low IGF-1 levels. After six months of vitamin D replacement and near-normalisation of 25-OH vitamin D (49 nmol/l, ref. 50–120 nmol/l), IGF-1 level had almost normalised (18.6 nmol/l, ref 19–66 nmol/l). Although GHRH arginine test will be repeated to definitively rule out GHD, it was remarkable that IGF-1 levels clearly increased after treatment of severe vitamin D deficiency. Especially in this patient with needle-fear, this could avoid a lot of stress.

Conclusion: In our patient with childhood onset GHD, IGF-1 levels nearly normalised after treatment of his severe vitamin D deficiency. Especially as fear of needles is common during the transition phase (20–50% in adolescents and 20–30% in young adults), it is worth reassessing IGF-1 levels after vitamin D supplementation, to avoid needless GH injections.

Reference: 1. McLenon J, Rogers MAM. The fear of needles: A systematic review and meta-analysis. J Adv Nurs. 2019 Jan;75(1):30–42. doi: 10.1111/jan.13818. Epub 2018 Sep 11. PMID: 30109720.