Bone mineral homeostasis, bone growth, and mineralisation during years of pubertal growth: A unifying concept

Abstract

Serum calcium, magnesium, proteins, phosphate, and immunoparathyroid hormone were measured in 338 normal children and adolescents aged between 7 and 20 years and in 123 normal adults aged between 21 and 50 years. Protein corrected serum calcium and magnesium remained stable throughout the study. Despite hyperphosphataemia protein corrected calcium exceeded the concentrations of normal adults. Serum phosphate and the Ca x P product greatly exceeded adult values and fell rather slowly towards adult levels after the pubertal growth spurt. Serum immunoparathyroid hormone tended to exceed normal adult values and judged high for the level of serum calcium. Similarities between mineral metabolism in childhood and adolescence and in acromegaly were striking. On this basis and in the light of studies demonstrating stimulatory actions of gonadal hormones on growth hormone and of growth hormone on the secretion of parathyroid hormone and 1,25-dihydroxyvitamin D3, a unifying concept is developed. This concept places growth hormone in the unique position of being the main driver and coordinator during childhood and adolescence of bone growth and mineralisation on the one hand, and of blood mineral homeostasis on the other. Gonadal hormones probably express some of their actions through stimulation of growth hormone secretion and others by different mechanisms. According to this concept growth hormone is maintaining the Ca x P product at a suitable high level as long as growth hormone and gonadal hormones deliver bone matrix for mineralisation at a high rate.