Association between high normal-range thyrotropin concentration and carotid intima-media thickness in euthyroid...

There are currently no established cutoff levels for thyrotropin (TSH) within the reference intervals associated with carotid atherosclerosis to prevent the onset of cardiovascular diseases. The present study aimed to determine the TSH cutoff level associated with carotid maximum intima-media thickness (max IMT) in euthyroid premenopausal, perimenopausal and postmenopausal women.

We conducted a cross-sectional study of 468 euthyroid women who had not been treated for or diagnosed with cardiovascular diseases and/or metabolic disorders among 1221 Japanese women who participated in a comprehensive medical examination at the Hidaka Hospital, Japan. Participants' weight, blood pressure, plasma glucose, serum lipoprotein, free thyroxine and TSH were measured and an interview about menstruation was conducted. Carotid ultrasonography was performed to determine max IMT.

Max IMT significantly increased stepwise as menopausal status progressed (p < 0.001). Serum TSH levels were significantly higher in participants with carotid plaques, defined as max IMT ≥1.1 mm (p = 0.038), and were independently associated with the presence of carotid plaque using multivariate logistic regression analysis (β =1.218, p = 0.036). In postmenopausal women, significantly higher carotid max IMT values were observed in women with serum TSH ≥2.5 μIU/mL compared with women with concentrations <2.5 μIU/mL (p = 0.018) without elevated total cholesterol and low-density lipoprotein cholesterol concentrations. These differences were not observed in premenopausal women.

Laboratory finding of serum TSH concentration ≥2.5 μIU/mL may be useful to assess risk of atherosclerosis, especially in postmenopausal women.