Effects of Triiodothyronine Administration in Patients with Chronic Renal Failure

Summary Clinically euthyroid patients with severe, chronic, non‐thyroidal illnesses usually have decreased serum total and absolute free T 3 concentrations. Since T 3 is the metabolically more active of the two thyroid hormones, it has been suggested that these patients may be hypothyroid and thus may benefit from T 3 therapy. To test this hypothesis, five patients with chronic renal failure requiring maintenance haemodialysis were treated with 5 μg T 3 eight hourly, increasing at three weekly intervals to 10 μg eight hourly, 20 μg eight hourly and finally 30 μg eight hourly. The mean ± SD serum T 3 level did not change over the 12 week period (1–42± 0–17 vs. 141 ± 0–26 nmoll‐1 ) whilst the mean serum T 4 and TSH levels fell from 87 0± 15 2 to 47 5± 18 8 nmol l ‐1 and 19 ± 0–9 to 1 3± 1 6 mU 1 ‐1 respectively. Only the change in T 4 levels was significant (P < 0005). A significant decrease in mean serum T 4 levels was apparent even after the treatment period with 5 μg T 3 eight hourly (87 0±15‐2 vs. 51 2±15 7; P <0005). The mean fasting serum triglyceride level fell from 1 16 ± 0 74 to 0 94 ± 0 74 mmoll ‐1 (P <005) and the mean fasting serum cholesterol level fell from 6 06± 1 13 to 4 69± 1 10 mmoll ‐1 (P < 005). There were no subjective improvements in any of the patients. From the marked changes in serum T 4 levels during the administration of T 3 , it is concluded that, prior to treatment, the patients were biochemically euthyroid and not hypothyroid and thus did not require T 3 therapy.