Background: Results of studies on associations between triiodothyronine serum levels and mortality after acute ischemic stroke (AIS) are inconsistent. Therefore, the aim of this prospective study was to evaluate links between serum levels of thyroid axis associated hormones and all-cause mortality during 1 year after AIS.
Methods and results: This study involved 255 patients with AIS. Patients were divided into two groups: those who survived 1 year after their index stroke and those who not, and by quartiles of free triiodothyronine (FT3) and ΔFT3 (difference between basal FT3 and repeated FT3 on discharge) hormone serum concentrations. To assess serum levels of thyroid stimulating hormone (TSH), FT3 and free tetraiodothyronine (FT4), venous blood was taken from all included patients on admission to hospital. On discharge, blood tests were repeated for 178 (69.8%) patients. Study endpoints were overall mortality within 30, 90 and 365 days after AIS.
Results: Compared with the survivals, those who died had significantly lower mean FT3, FT3/FT4 ratio in all periods and lower median TSH within 30 days. Higher FT3 serum levels versus lower, even after adjustment for included important variables, remained significant for lower odds of death within 365 days after AIS (OR=0.57; 95% CI: 0.33-0.97, p=0.04), but added insignificant additional predictive value to the NIHSS score or age. Kaplan-Meier survival curves demonstrated that the first FT3 quartile was significantly associated with increased mortality compared with all other quartiles within 365 days after AIS. With ΔFT3 quartiles no such association was found.
Conclusions: Higher FT3 levels on admission versus lower are significantly associated with lower mortality within 365 days after AIS. FT3 serum levels changes over time didn't show any association with mortality within first year.
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