Effects of acute and chronic zinc administration on growth velocity in patients with hypopituitarism

Zinc is a metal that plays an important role in growth and development. It is capable of releasing growth hormone (GH) in vitro as well as in vivo and to promote an increase in the synthesis of insulin-like growth factor (IGF-I). We studied 16 prepubertal patients with hypopituitarism with the objective of evaluating serum zinc levels and the effect of its acute and chronic administration on growth velocity, pubertal development, pituitary hormones release and on the levels of IGF-I and sexual steroid hormones. We compared the serum zinc levels of patients with hypopituitarism with the levels of 15 children with constitutional short stature. We observed that patients with hypopituitarism, like patients with constitutional short stature, did not have abnormal serum zinc levels. After acute and chronic zinc administration, hormone levels (GH, IGF-I, PRL, TSH, T3, T4, CORTISOL, TESTOSTERONE, ESTRADIOL, and DHEA-S) did not change, in spite of the significant increase in zinc serum levels. The chronic use of zinc, alone, did not increase growth velocity, which happened during growth hormone therapy and was more intense after zinc association. After the withdrawal of the metal and continuing growth hormone therapy, we observed a significant decrease in growth velocity. All patients remained clinically and laboratorially prepubertal during all the study period. We conclude that the effect of zinc on growth depends on the level of growth hormone and that it can be used as an auxiliary therapy for hypopituitarism, even in patients who do not present with low serum zinc levels.