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Euthyroidism linked to higher CVD risk factors for adults
Normal thyroid function was associated with cardiovascular disease risk factors and adiposity measures cross-sectionally, but not longitudinally, according to new data.
“Multiple lines of evidence suggest that the concentrations of [thyroid-stimulating hormone] and free thyroxine within the normal physiological range are associated with clusters of metabolic abnormalities and measures of body fat distribution,” Jane J. Lee, PhD, a postdoctoral research fellow at Boston’s Children’s Hospital, and colleagues wrote. “Specifically, higher TSH and lower free T4 within the reference range have been shown to be associated with unfavorable CVD risk factors and body fat composition.”
Researchers used data from the third-generation cohort of the Framingham Heart Study to perform cross-sectional and longitudinal associations of thyroid function within normal range with CVD risk factors and adiposity measures. Thyroid function was evaluated by TSH and free T4 concentrations.
In the cross-sectional analysis, researchers found that higher TSH concentrations were associated with increased odds of hypertriglyceridemia (OR = 1.1), as well as higher BMI (beta = 0.19 kg/m2), total cholesterol (beta = 0.05 mmol/L), triglycerides (beta = 0.0006 mmol/L) and subcutaneous adipose tissue volume (beta = 38.8 cm3; all P < .05). Additionally, free T4 was inversely associated with metabolic and adiposity-related CVD risk factors in the cross-sectional analysis (obesity, OR = 1.17; hypertriglyceridemia, OR = 1.09; BMI, beta = 0.42 kg/m2; total cholesterol, beta = 0.05 mmol/L; triglycerides, beta = 0.0002 mmol/L; visceral adipose tissue volume, beta = –20.7 cm3; all P < .05). However, baseline TSH and free T4 levels were not longitudinally associated with CVD risk factors and adiposity measures during 6.1 years of follow-up.
“The absence of a longitudinal association between thyroid function with metabolic and adiposity-related CVD risk factors may suggest that changes in CVD risk profiles or body fat distribution within the euthyroid range may precede changes in thyroid function rather than the other way round,” the researchers wrote. “Specifically, more adverse CVD risk factors or excessive fat accumulation could have led to altered secretion of thyroid hormones by affecting the endocrine system that contributes to the regulation of the hypothalamic–pituitary–adrenal axis. This is supported by weight-loss studies that demonstrated decreased TSH concentration after weight loss among obese participants with normal TSH range.” – by Cassie Homer
Disclosure: Lee reports no relevant financial disclosures. One researcher reports being employed by Merck.