Carotid artery intima media thickness is inversely related to serum free thyroxine in euthyroid subjects.
OBJECTIVE
The effect of thyroid function on cardiovascular risk may extend to the euthyroid range. In euthyroid subjects, we determined whether carotid artery intima media thickness (IMT), a measure of subclinical atherosclerosis, is related to thyroid function.


METHODS
Cross-sectional study in a cohort of 78 nonsmoking, predominantly middle-aged, euthyroid subjects (44 men and 34 women, mean age 56 years, TSH between 0.5 mU/l and 4.0 mU/l and FT4 between 11.0 pmol/l and 19.5 pmol/l).


METHODS
IMT (mean of three segments in both carotid arteries by ultrasonography), clinical factors, insulin resistance (HOMA(ir)), plasma lipids, C-reactive protein (CRP), serum FT4, TSH and thyroid autoantibodies.


RESULTS
In several multiple linear regression models, age- and sex-adjusted IMT was found to be independently related to either pulse pressure and body mass index (BMI), to high density lipoprotein (HDL) cholesterol or to FT4, but not to TSH, thyroid autoantibodies, HOMA(ir), CRP, non-HDL cholesterol and triglycerides. In a subsequent model which included age, sex, pulse pressure, body mass index (BMI), HDL cholesterol and FT4, IMT was independently and positively related to age (beta = 0.43, P < 0.001), male sex (beta = 0.34, P = 0.014), pulse pressure (beta = 0.29, P = 0.002), BMI (beta = 0.24, P = 0.007) and inversely related to FT4 (beta = -0.19, P = 0.046). IMT was also inversely related to FT4 in a model which included HDL cholesterol, non-HDL cholesterol and triglycerides.


CONCLUSIONS
In euthyroid subjects, IMT is associated with FT(4), after controlling for clinical factors, lipid levels and thyroid autoantibodies. These findings raise the possibility that, even within the euthyroid range, low normal thyroid function may adversely affect cardiovascular risk.
Dullaart
Robin P F
RP
Department of Endocrinology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. r.p.f.dullaart@int.umcg.nl
de Vries
Rindert
R
Roozendaal
Carolien
C
Kobold
Anneke C Muller
AC
Sluiter
Wim J
WJ
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D050197:Atherosclerosis / Q000097:blood / Q000473:pathology; D001323:Autoantibodies / Q000097:blood; D002097:C-Reactive Protein / Q000032:analysis; D002339:Carotid Arteries; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007333:Insulin Resistance; D016014:Linear Models; D008055:Lipids / Q000097:blood; D008297:Male; D008875:Middle Aged; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood*; D017540:Tunica Media / Q000000981:diagnostic imaging / Q000473:pathology*; D014463:Ultrasonography
D001323:Autoantibodies; D008055:Lipids; D013972:Thyrotropin; D002097:C-Reactive Protein; D013974:Thyroxine