Comparison between serum free triiodothyronine levels and body fluid distribution in hemodialysis patients

Abstract

Low free triiodothyronine (fT3) has been associated with the presence of malnutrition-inflammation syndrome in patients with end-stage renal disease (ESRD) and decreased overall survival in ESRD. Since thyroid hormone has a particular effect on body fluid status, we hypothesized that hemodialysis patients with low-T3 syndrome might have interstitial edema. In this study, we examined the relationship between levels of thyroid hormone and body composition parameters in Japanese hemodialysis patients. The subjects were 52 patients on maintenance hemodialysis. Serum levels of thyroid hormone and atrial natriuretic peptide (hANP) were measured. Body composition parameters were measured using a bioimpedance body composition analyzer. Serum fT3 had positive correlations with body mass index (BMI), body fat mass (BFM), total body water (TBW) and intracellular water (ICW), and negative correlations with the ratio of extracellular water to total body water (ECW/TBW) and hANP. There were no correlations between serum fT4 and any body composition parameter. The 49 patients with data at baseline and after 1year were divided into groups with increased (n=33) and decreased (n=16) fT3 after 1year. ΔBMI and ΔBFM were significantly lower and ΔTBW, ΔICW, ΔECW and ΔECW/TBW (changes over 1year from baseline) were significantly higher in patients with decreased fT3 compared to those with increased fT3. There was no significant difference in ΔhANP or Δcardiothoracic ratio between the two groups. These results show that a decrease in fT3 might be associated with emaciation and interstitial edema in Japanese hemodialysis patients.