Association of Triiodothyronine Levels with Left Ventricular Function, Cardiovascular Events, and Mortality in Hemodialysis Patients

Abstract

Background Hemodialysis (HD) patients have altered free triiodothyronine (fT3) levels. A low fT3 level is a strong and inverse mortality predictor in HD patients. However, little is known about the relationship between fT3 and left ventricular function in HD patients. Methods A total of 128 maintenance HD patients were enrolled in this study. A thyroid function test with blood sampling and echocardiography was conducted. Low-T3 syndrome was defined as fT3 level <3.62 pmol/L and normal thyroid stimulating hormone (TSH). Overall mortality and rate of cardiovascular (CV) events were assessed during 48 months of follow-up. Results Low-T3 syndrome was detected in 57 (44.5%) of the 128 patients. Patients with low-T3 syndrome had a shorter duration of HD (49.1 vs. 73.3, p = 0.01), and lower serum albumin (35.1 vs. 40.4 g/L, p<0.001), left ventricular ejection fraction (LVEF; 54.7% vs. 63.9%, p<0.001), and fractional shortening at endocardial levels (endoFS; 29.3% vs. 34.8%, p = 0.001) compared to those with normal fT3 levels. In multivariate linear regression, LVEF, albumin, and duration of HD were independently correlated with fT3 levels. In addition, fT3 was also correlated with LVEF. During the study period, 13 (10.1%) patients died, CV events occurred in 15 (11.7%) patients. In Cox regression analysis, low fT3 level and elevated high-sensitivity C-reactive protein (hs-CRP) were associated with mortality and CV events. Conclusions In HD patients, fT3 level is positively correlated with LVEF. Low fT3 level and elevated hs-CRP predicted all-cause mortality and CV events.