L-thyroxine-induced hyperthyroidism affects elements and zinc in rats.

There is a significant relation between thyroid hormones and zinc. The establishment of low blood zinc levels in hypothyroidism as opposed to high blood zinc levels in hyperthyroidism testifies to this relation. The present study aims to examine the changes in levels of some elements in sera of rats with induced hyperthyroidism as well as the relation between these changes and zinc.Thirty adult male rats of Sprague-Dawley type were equally allocated to three groups, particularly Group 1: General Control, Group 2: Sham-hyperthyroidism Group, and Group 3: Hyperthyroidism Group. Subsequent to decapitating the animals, their blood samples were taken and analyzed with the help of atomic emission spectrophotometer in terms of serum levels of zinc, selenium, calcium, magnesium, phosphorus, chromium, copper and iron. The levels of zinc, selenium and calcium were higher (p<0.01), while those of chromium, copper, iron and phosphorus were lower (p<0.01) in Group 3, relative to groups 1 and 2. These parameters were not different in groups 1 and 2.The results obtained from the study indicate that hyperthyroidism brings about some changes in the levels of some elements in rats. These changes might be associated with the elevation of zinc levels in hyperthyroidism (Tab. 2, Ref. 41).