The influence of chronic renal failure on serum and urinary thyroid hormone levels.

Abstract

ABSTRACT The effects of various degrees of chronic renal failure on serum and urinary thyroid hormones were studied in 10 patients with a mean creatinine clearance (Cr.Cl.) of 23 ml/min (group A), in 11 patients with a Cr.Cl. of 5.7 ml/min (group B), and in 60 healthy euthyroid subjects with normal renal function. We found a significant decrease (P < 0.01) of serum total thyroxine (T4) (5.3 ±1.9 (sd) μg/100 ml in group A and 4.1 ± 1.5 in group B), serum total triiodothyronine (T3) (65.4 ± 17.4 ng/100 ml ~57.4 ± 13.9), serum free T4 (5.60 ± 1.74 arb.U ∼ 4.45 ± 1.61), and serum free T3 (69.51 ± 21.22 arb.U ∼ 62.09 ± 12.39). T3 uptake test and basal thyroid stimulating hormone (TSH) values were normal in both groups of renal patients. No statistical significance was found in T4 excretion in urine. Urinary T3 excretion was significantly reduced (P < 0.01) in group A (27 ± 44 ng/24 h), and undetectable in terminal renal failure. Urinary protein excretion was non-selective and low (median 0.2 g/24 h and 0.7 g/24 h, respectively). Conclusively we have found reduced levels of serum total and free T3, and in contradiction to most investigators substantially reduced levels of serum total and free T4. Urinary excretion of T4 and T3 reflects the low levels of free serum hormones and the tubular impairment.