Study on the effect of high calcium intake on serum protein bound iodine and urinary excretion of iodine

  Iodine deficiency remains a major health problem in the world, including some parts of Iran. It has been recognized that there is usually a close and inverse relationship between iodine in the soil and water and presence of endemic goiter. Calcium has been suggested as one of goitrogens, though the definite role, extent and mechanism particularly in human have not been studied. Serum protein-bound iodine and urinary iodine excretion in male and female volunteers were investigated. To measure serum iodide concentration, blood samples were collected from 26 male and female subjects, with normal diet and two hours after consumption of calcium (10 mg/kg b.w.), iodine (5 µ g/kg b.w.) or iodine plus calcium. In another study carried out on 33 male and female volunteers, urinary iodine excretion during four different conditions was measured. The results indicate that high calcium intake with normal diet does not significantly effect serum protein-bound iodine concentrations, but high calcium intake plus iodine with normal diet can significantly increase serum protein-bound iodine concentrations. The result of this study, suggest that calcium significantly affects the iodine metabolism, when iodine intake is low.