title: Low-normal thyroid function and novel cardiometabolic biomarkers.
abstract: The concept is emerging that low-normal thyroid function, i.e., either higher thyroid-stimulating hormone or lower free thyroxine levels within the euthyroid reference range, could contribute to the development of atherosclerotic cardiovascular disease. It is possible that adverse effects of low-normal thyroid function on cardiovascular outcome may be particularly relevant for specific populations, such as younger people and subjects with high cardiovascular risk. Low-normal thyroid function probably relates to modest increases in plasma total cholesterol, low density lipoprotein cholesterol, triglycerides and insulin resistance, but effects on high density lipoprotein (HDL) cholesterol and non-alcoholic fatty liver disease are inconsistent. Low-normal thyroid function may enhance plasma cholesteryl ester transfer, and contribute to an impaired ability of HDL to inhibit oxidative modification of LDL, reflecting pro-atherogenic alterations in lipoprotein metabolism and HDL function, respectively. Low-normal thyroid function also confers lower levels of bilirubin, a strong natural anti-oxidant. Remarkably, all these effects of low-normal thyroid functional status appear to be more outspoken in the context of chronic hyperglycemia and/or insulin resistance. Collectively, these data support the concept that low-normal thyroid function may adversely affect several processes which conceivably contribute to the pathogenesis of atherosclerotic cardiovascular disease, beyond effects on conventional lipoprotein measures.
authors.affiliation: Department of Endocrinology, University of Groningen and University Medical Center Groningen, Groningen, AV Groningen 19713, The Netherlands. l.j.n.van.tienhoven-wind@umcg.nl.
authors.forename: Lynnda J N
authors.initials: LJ
authors.lastname: van Tienhoven-Wind
authors.affiliation: Department of Endocrinology, University of Groningen and University Medical Center Groningen, Groningen, AV Groningen 19713, The Netherlands. r.p.f.dullaart@umcg.nl.
authors.forename: Robin P F
authors.initials: RP
authors.lastname: Dullaart
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood*; D002318:Cardiovascular Diseases / Q000097:blood* / Q000175:diagnosis*; D002352:Carrier Proteins / Q000097:blood; D002784:Cholesterol / Q000097:blood; D005260:Female; D006801:Humans; D007333:Insulin Resistance; D008075:Lipoproteins, HDL / Q000097:blood; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012307:Risk Factors; D013960:Thyroid Function Tests; D013961:Thyroid Gland / Q000378:metabolism*; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D014280:Triglycerides / Q000097:blood
chemical_list: D015415:Biomarkers; D002352:Carrier Proteins; D008075:Lipoproteins, HDL; D014280:Triglycerides; C030363:lipid transfer protein; D013972:Thyrotropin; D002784:Cholesterol; D013974:Thyroxine