Serum reverse T3 assay for predicting glucose intolerance in uremic patients on dialysis therapy.

Sixty patients with end stage chronic renal failure (CRF) enrolled in a dialysis program underwent studies of serum thyroid hormones and carbohydrate metabolic state. The aim of the study was: 1) to evaluate whether the glucose intolerance per se represents a factor for the alteration of circulating thyroid hormones; and 2) to explore the potential usefulness of specific thyroid hormones and particularly reverse T3 (RT3) as indicators for predicting glucose intolerance. Forty-two patients received hemodialysis and 18 were on intermittent peritoneal dialysis (IPD). CRF patients had reduced serum total T4 and T3 levels, slightly decreased RT3 and TBG concentrations and normal TSH values. There was no significant difference in serum thyroid hormone indices between HD and IPD patients. Glucose intolerance was found in 25 patients. Ten had fasting hyperglycemia and diabetic response to oral glucose tolerance test (OGTT), 15 had an impaired glucose tolerance according to the criteria of the National Diabetes Data Group. In CRF patients with glucose intolerance, serum T3 and T3/T4 molar ratio were significantly lower than in those with a normal OGTT response, whereas serum RT3 and RT3/T4 molar ratio were found to be higher. In the whole group of CRF patients these serum thyroid hormones closely correlated with glucose tolerance indices. To investigate the usefulness of serum RT3 assay in predicting glucose intolerance we compared the outcome of the OGTT and serum RT3 values. Using the results of the OGTT as the true diagnosis of glucose intolerance, serum RT3 assay showed a diagnostic specificity of 94.2% and a sensitivity of 100%. In conclusion these results suggest that: 1) the glucose intolerance, which frequently occurs in uremia, may influence circulating thyroid hormones probably leading to a shift in the peripheral tissue conversion of T4 from T3 to RT3; and 2) serum RT3 assay could assume a clinical interest in assessing carbohydrate metabolic state in treated end stage renal failure independently of the type of dialysis therapy.