Renal failure and thyroid function tests: the effects of commencing haemodialysis

Thyroid function tests are often noted to be abnormal in patients with chronic renal failure. We investigated thyroid and pituitary function in six patients with renal failure. In order to study the effects of improvement in the uraemic state on these tests, they were repeated after regular haemodialysis was commenced. Serum thyroxine and free thyroxine levels were at the lower limit of the normal range prior to dialysis and both showed a non-significant increase after regular haemodialysis was started. The TSH response to TRH (TRH test) decreased in five of the six patients after dialysis but this did not achieve statistical significance. The abnormalities in thyroid function tests often observed in clinically euthyroid patients with renal failure do not appear to change significantly after the institution of regular dialysis.