Abstract
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.
Key words
free triiodothyronine - acute ischaemic stroke - death
