[Can FT3 levels facilitate the detection of inflammation or catabolism and malnutrition in dialysis patients?].

INTRODUCTION

Low serum free triiodothyronine (FT3) levels have been reported in a high percentage of chronic renal failure (CRF) patients and have been considered as independent predictors of mortality in both hemodialysis (HD) and peritoneal dialysis (PD). A reduction in thyroid function in dialysis patients could be a marker of malnutrition and/or inflammation.

OBJECTIVE

Our aim has been to evaluate the incidence of low T3 syndrome in a group of dialysis patients and analyze its relationship with different parameters of malnutrition and inflammation. PATIENTS AND METHODS We included 32 stable dialysis patients (24 HD and 8 DP); mean age +/- SD 71.2 +/- 11.7 years; 46.9% males; 15.6% diabetics; mean time on dialysis 47 +/- 43 months. The following parameters were measured in every patient: thyrothropin (TSH), Free T4 (FT4) and Free T3 (FT3); biochemical data related to nutritional status; anthropometric measurements, bioelectrical impedance vector analysis (BIVA), and dietary survey of three consecutive days. Statistical analysis was performed by using SPSS 11.0.

RESULTS

Mean hormonal values of thyroid function were: TSH 2,2 +/- 1.5 U/ml (range: 0,4-5.0); FT4 14.7 +/- 2.3 pmol/l (range: 11.0-23.0) and FT3 4,0 +/- 0.71 pmol/l (range: 3.95-6.80). Only 2 patients (6.3%) showed low FT4 levels and another 2 patients increased TSH levels, whereas 17 patients (53.1%) presented with low FT3 levels. We did not found any correlation between serum FT3, FT4 and TSH levels. We found a correlation between FT3 and inflammation/nutritional parameters: prealbumin (r = 0,36; p = 0,04); transferrin (r = 0,40; p = 0,025); PCR (r = -0.38; p = 0,039); and IGF-I (r = 0,38; p = 0,03); body mass index (BMI) (r = 0,51; p = 0,002); arm circumference (AC) (r = 0,65; p = 0,000), and arm muscle circumference (AMC) (r = 0,72; p = 0,000). FT3 levels were also correlated with BIVA parameters: phase angle (r = 0,54; p = 0,002); muscle mass percentage (r = 0,49; p = 0,005); and cell mass percentage (r = 0,53; p = 0,02), but not with any data of fat mass. AMC was the only variable that independently correlated with FT3 levels in the multivariate regression analysis (r = 0,69; r2: 0,48; p = 0,000)

CONCLUSION

Half of our dialysis patients have decreased levels of serum FT3 without alteration on FT4 or TSH. Low FT3 levels are correlated bioquimical and anthropometric parameters indicators of malnutrition and inflammation. Periodical measurement of FT3 levels could be used by clinicians as an accesible and reproducible method to detect such states.