The association between TSH within the reference range and serum lipid concentrations in a population-based study. The HUNT Study.
OBJECTIVE
The association between TSH and serum lipids in people with no apparent thyroid disease is insufficiently understood. We have studied the association between normal thyroid function, defined as TSH within the reference range of a general population, and concentrations of serum lipids.


METHODS
Cross-sectional, population-based study with 30,656 individuals without known thyroid disease.


METHODS
Using general linear models, we calculated mean concentrations of total serum cholesterol, low-density lipoprotein (LDL) cholesterol, non-high-density lipoprotein (HDL) cholesterol, HDL cholesterol and triglycerides across categories of TSH.


RESULTS
Within the reference range of TSH, there was a linear and significant (P for trend <0.001) increase in total serum cholesterol, LDL cholesterol, non-HDL cholesterol and triglycerides, and a linear decrease (P for trend <0.001) in HDL cholesterol with increasing TSH. Subgroup analyses showed statistically significant associations for all lipids in men above 50 years of age, and for triglycerides in all age groups. For women, associations were statistically significant in all age groups except for HDL cholesterol in women below 50 years of age. The associations with triglycerides and HDL cholesterol were stronger among overweight than normal weight individuals.


CONCLUSIONS
Within the range of TSH that is considered clinically normal, we found that increasing level of TSH was associated with less favourable lipid concentrations. The association with serum lipids was linear across the entire reference range of TSH.
Asvold
Bjørn O
BO
Department of Public Health, Faculty of Medicine, Norwegian University of Science and Technology, N-7489 Trondheim, Norway.
Vatten
Lars J
LJ
Nilsen
Tom I L
TI
Bjøro
Trine
T
D000328:Adult; D017677:Age Distribution; D000368:Aged; D015415:Biomarkers / Q000097:blood; D008076:Cholesterol, HDL / Q000097:blood; D008078:Cholesterol, LDL / Q000097:blood; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D006949:Hyperlipidemias / Q000097:blood* / Q000453:epidemiology*; D016014:Linear Models; D008055:Lipids / Q000097:blood*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood / Q000453:epidemiology; D012016:Reference Values; D012307:Risk Factors; D017678:Sex Distribution; D013961:Thyroid Gland / Q000378:metabolism*; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000097:blood; D014280:Triglycerides / Q000097:blood
D015415:Biomarkers; D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D008055:Lipids; D014280:Triglycerides; D013972:Thyrotropin; D013974:Thyroxine