OBJECTIVE: Little is known about the impact of low triiodothyronine (T3) levels 
on mortality in end-stage renal disease (ESRD) patients starting hemodialysis 
(HD) and whether this impact is mediated by malnutrition, inflammation, or 
cardiac dysfunction.
DESIGN AND METHODS: A prospective cohort of 471 incident HD patients from 36 
dialysis centers within the Clinical Research Center for ESRD in Korea was 
selected for this study. Based on the median value of T3, patients were divided 
into 'higher' and 'lower' groups, and all-cause and cardiovascular (CV) 
mortality rates were compared. In addition, associations between T3 levels and 
various nutritional, inflammatory, and echocardiographic parameters were 
determined.
RESULTS: Compared with those in the 'higher' T3 group, albumin, cholesterol, and 
triglyceride levels, lean body mass estimated by creatinine kinetics (LBM-Cr), 
and normalized protein catabolic rate (nPCR) were significantly lower in 
patients with 'lower' T3 levels. The 'lower' T3 group also had a higher left 
ventricular mass index (LVMI) and a lower ejection fraction (EF). Furthermore, 
correlation analysis revealed significant associations between T3 levels and 
nutritional and echocardiographic parameters. All-cause and CV mortality rates 
were significantly higher in patients with 'lower' T3 levels than in the 
'higher' T3 group (113.4 vs 18.2 events per 1000 patient-years, P<0.001, and 
49.8 vs 9.1 events per 1000 patient-years, P=0.001, respectively). The 
Kaplan-Meier analysis also showed significantly worse cumulative survival rates 
in the 'lower' T3 group (P<0.001). In the Cox regression analysis, low T3 was an 
independent predictor of all-cause mortality even after adjusting for 
traditional risk factors (hazard ratio=3.76, P=0.021). However, the significant 
impact of low T3 on all-cause mortality disappeared when LBM-Cr, nPCR, LVMI, or 
EF were incorporated into the models.
CONCLUSION: Low T3 has an impact on all-cause mortality in incident HD patients, 
partly via malnutrition and cardiac dysfunction.