[Alterations of zinc levels in patients with thyroid disorders]

It is known that patients with hyperthyroidism have a lower zinc content in their erythrocytes, and that this decrement returns to normal after treatment with anti-thyroid drugs. This study was designed to investigate the alteration of body zinc levels in thyroid disorder. Two groups of out-patients associated with hyperthyroidism or hypothyroidism, and a group of normal healthy controls were collected. Zinc contents in the blood, hair and 24-hour urine samples were determined by a flame atomic absorption spectrometer. The results showed that patients with hyperthyroidism had a lower erythrocyte zinc level and an increased urinary zinc excretion (p < 0.05). The hypothyroidism had a higher hair zinc content and a decrement in urinary zinc excretion (p < 0.05). Body zinc levels, excluding the plasma zinc, held a certain correlation to the plasma thyroid hormones levels. The urinary zinc levels showed a more parallel variation in the thyroid disorders (p < 0.05). This data indicates that the alteration of urinary zinc levels might be a useful index for thyroid disorder evaluation. Body zinc could also play a physiological role in the metabolic regulation(s) of a thyroid disorder.