The relationship between time of sampling over 24 hours and thyroid function parameters and thyroid peroxidase antibody (TPOAb) levels. Restricted cubic spline plots with three knots demonstrating the association of time of sampling (x axis) with the predicted mean thyroid function and TPOAb parameters (black lines) with 95% confidence intervals (gray area). All associations adjusted for age, sex, center, body mass index, smoking status, type of acute myocardial infarction, pain to sampling time, serum creatinine, history of ischemic heart disease, diabetes mellitus, cerebrovascular disease, hypertension, atrial fibrillation and hypothyroidism.