Effects of chronic hemodialysis on thyroid function in chronic renal failure

Thyroid function was studied in 54 patients undergoing chronic hemodialysis. Serum thyroxine, triiodothyronine and free thyroxine and the free thyroxine index were significantly lower than normal. The levels of both serum thyroxine and the free thyroxine index tended to fall progressively the longer the patients were on hemodialysis. These findings, in association with low serum TSH levels and normal increase in radioactive iodine uptake by the thyroid after TSH injection, suggest that a defect in pituitary secretion of TSH may be responsible. Although some patients experienced symptomatic improvement after treatment with L-thyroxine the efficacy of this form of treatment in patients on chronic hemodialysis has not yet been established.