An interaction between growth hormone/insulin-like growth factor-1 and vitamin D in children with short stature

Abstract

There are disorders in the growth hormone (GH)/growth factors system in a significant part of patients with short stature; first of all, this concerns such diseases as growth hormone deficiency, where there is a sharp decrease in GH, insulin-like growth factor-1 (IGF-1). The association between vitamin D and GH/growth factor system remains unclear. It was found that vitamin D is able to increase IGF-1 level in healthy individuals. Linear growth is accelerated after treatment of vitamin D deficiency in children, which may indicate the linking role of vitamin D between the proliferative cells of the growth plate cartilage and GH/growth factor system.Research objective: to determine 25-hydroxyvitamin D level in blood plasma in children with short stature, depending on the state of GH/IGF-1 system.Materials and methods. Study included 101 children with short stature: 33 children with partial somatotropic insufficiency (group 1); 44 children with complete somatotropic insufficiency (group 2); 24 children with syndrome of biologically inactive GH (group 3). Patients in groups 1 and 2 had a confirmed GH deficiency and a decrease or sharp decrease in of IGF-1 level; patients in group 3 had a normal stimulated release of GH against the background of a reduced IGF-1 level. GH, IGF-1, 25-hydroxyvitamin D, thyroid-stimulating hormone, and free thyroxine were determined in all children.Results. The average level of vitamin D in three groups corresponded to the vitamin deficiency according to international standards and was 52.24 ± 5.99 nmol/l in patients with partial somatotropic insufficiency, 67.6 ± 5.35 nmol/l in patients with complete somatotropic insufficiency and 58, ± 7.91 nmol/l in patients with syndrome of biologically inactive GH. A direct correlation was found between vitamin D and background GH level, stimulated GH level in children with both partial and complete somatotropic insufficiency. A direct correlation between vitamin D and IGF-1 level in this group of patients was also detected.Conclusions. It is advisable to determine the serum 25(OH)D in all children with short stature. Vitamin D levels should be taken into account in insulin/clonidine diagnostic tests in order to obtain a realistic indication of stimulated GH and IGF-1 levels.