Hyperthyroidism with reference to elevated serum FT3 and FT4 levels in patients with ischemic stroke

Ischemic stroke and hyperthyroidism are common diseases and may be associated with each other. The aim of the present study was to investigate whether patients with hyperthyroidism are at risk of developing ischemic stroke, whilst also exploring biochemical metabolism biomarkers and pathophysiological features. A total of 4,674 participants diagnosed with ischemic stroke were studied by retrospective analysis, of whom 4,092 cases had normal thyroid function (control group) and 582 cases were complicated with hyperthyroidism (hyperthyroidism group). Single-factor analysis and logistic regression analysis were applied to compare clinical parameters between patients with ischemic stroke with and without hyperthyroidism. The median serum levels of triiodothyronine (FT3), free thyroxine (FT4), cholesterol (CHO), and high-density lipoprotein (HDL) were significantly higher in hyperthyroidism group than control group; low-density lipoprotein (LDL) was higher in control group. Logistic regression analysis revealed that sex, age, FT3, FT4, lactate dehydrogenase and HDL were associated with ischemic stroke. Compared with those in the control group, the levels of CHO, LDL, HDL and lipoprotein in patients with hyperthyroidism were lower. Higher levels of serum FT3 [odds ratio (OR) 2.097, 95% CI, 1.795-2.499] and FT4 (OR, 1.503; 95% CI, 1.101-2.051) may lead to an elevated risk of ischemic stroke, compared with HDL (OR, 0.330; 95% CI, 0.194-0.561). Therefore, these results suggested that elevated levels of serum FT3 and FT4 were associated with increased risk for ischemic stroke. In conclusion, thyroid hormones may serve different roles based on age and may aggravate the cerebral infarction injury and worsen the prognosis of patients with hyperthyroidism.