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.