Thyroid function in hemodialysis

The relevance of the biochemical evidence of hypothyroidism in patients on regular hemodialysis is debatable. Several indexes of thyroid function were assessed in 46 patients undergoing chronic hemodialysis for 2 to 45 months. Low serum levels of thyroxine were found in 69.5% of the patients studied and of triiodothyronine (T3) in 46.5%. Low values of T3-Sephadex binding were noted in 17.3%, of free thyroxine index (FTI) in 26.3% and of radioiodine uptake in 19.3% of the patients; 13.0% had high levels of thyroid-stimulating hormone (TSH). The overall incidence of hypothyroidism, based on FTI and TSH, was 34.8%. We concluded that the diagnosis of hypothyroidism should be based on FTI and TSH levels, and that chronically hemodialyzed patients tend to exhibit biochemical rather than clinical hypothyroidism.