Modulation of the neuroendocrine system and immune functions by zinc supplementation in children with Down's syndrome.

Plasma levels of TSH, T4, T3, and reversal T3 (rT3) were measured in 51 children with trisomy of the chromosome 21 and in 15 controls. Levels of TSH were higher in children with DS than in controls and rT3 levels were decreased. However, T3 and T4 levels were in the normal range. Plasmic zinc and thymulin, a zinc-dependent thymic hormone, were also decreased. After dietary supplementation with ZnSO4, levels of plasmic zinc, thymulin, TSH and rT3 were restored. A follow up of DS children one year after the cessation of zinc therapy showed that plasma levels of zinc decreased and TSH lightly increased. Zinc deficiency may play a crucial role in the pathogenesis of thyroid gland disfunction which leads to the autoimmune hypothyroidism often observed in this syndrome.