Background: Abnormal thyroid function tests (serum thyrotropin [TSH], free thyroxine [T(4)] and free triiodothyronine [T(3)]) are frequently seen in hospitalized patients. Assessment of thyroid function in these patients is difficult. It has been suggested that acutely ill patients may be hypothyroid at the tissue level. Erythrocyte zinc (EZn) has been shown to be increased in hypothyroidism. The aim of this study was to examine EZn as an index of thyroid status of hospital patients.
Methods: In order to assess the thyroid status at tissue level, we measured EZn in 26 healthy subjects, 39 critically ill patients and 19 hospitalized geriatric patients. EZn was measured in young cells, as the effect of illness is likely to be seen in the newly formed cells.
Result: TSH and free T(3) were lower in critically ill patients and serum free T(3) was lower in geriatric patients. EZn in young cells was higher in both patient groups (by 13% and 23%, respectively). EZn in old cells was also higher in the geriatric group.
Conclusion: We conclude that EZn is higher in hospitalized patients, suggesting that these patients may be hypothyroid at the tissue level.