Association Between Vitamin D and Carboxy-Terminal Cross-Linked Telopeptide of Type I Collagen in Children During Growth Hormone Replacement Therapy

Vitamin D status and response to growth hormone treatment in prepubertal children with growth hormone deficiency

PURPOSE

To analyze whether vitamin D deficiency could condition the growth response to GH therapy, as well as to analyze if GH treatment modifies both seasonal variations and vitamin D levels in these patients.

METHODS

Retrospective study in 98 prepubertal children with GH deficiency (GHD), aged 4.1-8.9 years treated with GH. Growth rate and blood testing (calcium, phosphorus, IGF-I, 25(0H)D and PTH) were monitored at diagnostic and every six months until 24 months of treatment. A control group was recruited (247 healthy children, aged 3.8-9.7 years). The criteria of the US Endocrine Society were used for the definition of hypovitaminosis D.

RESULTS

There were no significant differences in vitamin D deficiency among control (12.5%) and GHD groups (15.3%) before starting treatment. Growth rate and IGF-1 and PTH increased (p < 0.05) during GH treatment, but there were no significant differences in calcium, phosphorus and 25(OH)D. There were no significant differences in growth rate and IGF-1, calcium and phosphorus levels in relation to the seasons along GH treatment. There was no correlation between 25(OH)D and IGF-1 during GH therapy. In every programmed control, patients with vitamin D deficiency showed lower growth rate (p < 0.05) compared to patients with vitamin D insufficiency or sufficiency.

CONCLUSION

GH treatment, at least during the first two years, does not modify the vitamin D levels. Vitamin D deficiency could condition the response to GH therapy so vitamin D monitoring should be considered as part of the routine evaluation of children with GH treatment.

Vitamin D and growth hormone in children: a review of the current scientific knowledge

Background

Human growth is a complex mechanism that depends on genetic, environmental, nutritional and hormonal factors. The main hormone involved in growth at each stage of development is growth hormone (GH) and its mediator, insulin-like growth factor 1 (IGF-1). In contrast, vitamin D is involved in the processes of bone growth and mineralization through the regulation of calcium and phosphorus metabolism. Nevertheless, no scientific study has yet elucidated how they interact with one another, especially as a dysfunction in which one influences the other, even if numerous biochemical and clinical studies confirm the presence of a close relationship.

Main body

We reviewed and analyzed the clinical studies that have considered the relationship between vitamin D and the GH/IGF-1 axis in pediatric populations. We found two main areas of interest: the vitamin D deficiency status in patients affected by GH deficit (GHD) and the relationship between serum vitamin D metabolites and IGF-1. Although limited by some bias, from the analysis of the studies presented in the scientific literature, it is possible to hypothesize a greater frequency of hypovitaminosis D in the subjects affected by GHD, a reduced possibility of its correction with only substitution treatment with recombinant growth hormone (rGH) and an improvement of IGF-1 levels after supplementation treatment with vitamin D.

Conclusions

These results could be followed by preventive interventions aimed at reducing the vitamin D deficit in pediatric age. In addition, further research is needed to fully understand how vitamin D and growth are intertwined.