Introduction
The burden of stroke in china is very serious and the annual stroke mortality rate is approximately 1.6 million, which has exceeded heart disease to become the leading cause of death and adult disability (1). Of all stroke types, ischemic stroke is the most prevalent accounting for 69.6% (2). Currently, ischemic stroke severity and prediction of functional outcome are assessed with standardized clinical criteria (3, 4). However, the prognostic value of these clinical parameters in ischemic stroke is quite subjective and insufficient, such that identification of new biomarkers may potentially improve the accuracy of the current prognostic scales for functional outcome.
Recent studies suggest that serum concentrations of thyroid hormones are altered in the acute phase of ischemic stroke and may have a potential influence on functional outcome (5, 6). There are some evidences that thyroid hormones play a neuroprotective role in the recovery of post-ischemic stroke (7) and display a protective association between subclinical hypothyroidism and better outcomes(8, 9) However, other studies suggest that lower serum concentrations of T3 are associated with poor outcome after ischemic stroke (6, 10).In addition, it is not well recognized whether there are any associations between FT3, the bioactive form of T3, and functional outcome of ischemic stroke. Studies on the relationship between FT3 levels and functional outcomes after ischemic stroke are controversial(10-16) .Thus, our study aimed to investigate whether the serum concentrations of thyroid hormones on admission, including thyroid stimulating hormone (TSH), free triiodothyronine (FT3), and free thyroxine (FT4) were associated with 3-month functional outcome in acute ischemic stroke.