Thyroid Dysfunction in Uremia: Evidence for Thyroid and Hypophyseal Abnormalities

Abstract

Disturbances in thyroid function and a high prevalence of goiter develop in patients on chronic hemodialysis. In patients on dialysis, mean serum thyroxine [T4] and triiodothyronine [T3] levels are lower than normal. Patients with chronic renal failure not on dialysis have mean serum T4 levels similar to normal subjects and low mean serum T3 levels. Both serum T4 and T3 concentrations decrease as the renal failure worsens. Both groups of patients with renal failure have a decreased serum T4 response to exogenous thyrotrophin [TSH] and a diminished serum TSH response to thyrotrophin-releasing hormone. These data suggest the presence of an intrathyroidal and a hypophyseal defect in uremic patients. Although serum iodide concentrations are elevated, there is no correlation between the level of serum iodide and the degree of renal failure. Therefore, no direct evidence was obtained that iodide excess is responsible for the abnormalities observed.