Previously unknown thyroid dysfunction in patients with acute ischemic stroke.

OBJECTIVES Opinions differ regarding the clinical significance of subclinical thyroid disorders. The aim of the present study was to evaluate the prevalence and influence of previously unknown overt or subclinical thyroid dysfunction in patients with acute ischemic stroke and to look for differences between cardio-embolic and non-embolic ischemic stroke. MATERIAL AND METHODS A total of 153 Swedish patients diagnosed with first-time acute ischemic stroke were included in the study and categorized for suspected cardio-embolic (n = 30) or non-embolic (n = 123) ischemic stroke depending on the presence of atrial fibrillation (AF). Blood samples were taken 48 h or earlier after onset of stroke symptoms. RESULTS Previously, unknown overt or subclinical thyroid dysfunction was found in 12%. Previously, unknown overt or subclinical hyperthyroidism was more common in the AF group (13%) compared to the non-AF group (3%), P = 0.048. Patients with AF had slightly higher concentrations of free T4 (15 vs 14 pm; P < 0.001), but there was no significant difference in concentrations of S-TSH or prevalence of thyroperoxidase (TPO) antibodies between the groups. CONCLUSIONS In patients with first-time acute ischemic stroke, unknown thyroid dysfunction is common, and unknown overt or subclinical hyperthyroidism is associated with cardio-embolic stroke.