Netherlands: CEC, an important antiatherogenic metric of HDL function is impaired during severe short-term hypothyroidism, according to a recent study in the Journal of Clinical Endocrinology & Metabolism.
Severe hypothyroidism impacts lipoprotein metabolism including an increase in high-density lipoprotein (HDL) cholesterol. However, its (severe hypothyroidism) effects on HDL function are ambiguous. To fill this knowledge gap, Thera P Links, University of Groningen, University Medical Center Groningen, RB Groningen, The Netherlands, and colleagues conducted the observational study to determine the impact of severe short-term hypothyroidism on HDL particle characteristics, HDL cholesterol efflux capacity (CEC), and HDL antioxidative capacity.
The study enrolled 17 thyroid cancer patients (median age, 46 years; 16 women) who had undergone total thyroidectomy. In this cohort, the median thyroid-stimulating hormone (TSH) level was 81.9 mU/L and free thyroxin was 2.3 pmol/L.
Outcome measures included HDL particle characteristics (nuclear magnetic resonance spectrometry), CEC (human THP-1-derived macrophage foam cells and apolipoprotein B-depleted plasma), and HDL anti-oxidative capacity (inhibition of low-density lipoprotein oxidation).
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Key findings of the study include:
During hypothyroidism plasma total cholesterol, HDL cholesterol and apolipoprotein A-I were increased.
HDL particle concentration was unchanged, but there was a shift in HDL subclasses toward larger HDL particles.
CEC was decreased, also when corrected for HDL cholesterol or HDL particle concentration.
HDL antioxidative capacity did not change.
"During severe short-term hypothyroidism CEC, an important antiatherogenic metric of HDL function, is impaired. HDL cholesterol and larger HDL particles are increased but HDL particle concentration is unchanged," wrote the authors.
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Combined, these findings suggest that HDL quality and quantity are not improved, reflecting dysfunctional HDL in hypothyroidism.
The study, "HDL Cholesterol Efflux Capacity is Impaired in Severe Short-Term Hypothyroidism Despite Increased HDL Cholesterol," is published in the Journal of Clinical Endocrinology & Metabolism.
DOI: https://academic.oup.com/jcem/article-abstract/105/9/e3355/5881625