High-density lipoprotein cholesterol (HDL-C), the "good cholesterol," transports cholesterol from the arteries to the liver for elimination. Previous studies have demonstrated an association between higher HDL-C and lower cardiovascular (CV) risk. Epidemiologic studies reported CV disease (CVD) reductions of around 2%-3% for every unit rise in HDL-C level. However, a recently published prospective, multicenter, cohort study found that very high levels of HDL-C (> 80 mg/dL [> 2.069 mmol/L]) were associated with adverse outcomes in patients with coronary heart disease (CHD), suggesting that hyperalphalipoproteinemia (HALP) can negatively affect CV mortality.
Here are five things about the role of HDL-C and the potential negative impact of HALP on CV health.
1. HDL-C is essential for lipid homeostasis.
HDL-C comprises various particles that differ in size, density, electrophoretic mobility, and apolipoprotein (Apo) content. ApoA-I and ApoA-II, the two major HDL-C apolipoproteins, are essential for normal HDL-C biosynthesis. ApoA-I constitutes about 70% of HDL-C protein while ApoA-II constitutes about 20%. The multiple proteins and lipids that comprise HDL-C not only assist in lipid metabolism but also play a role in acute-phase response, complement regulation, and proteinase inhibition. HDL-C plays an integral role in reverse cholesterol transport by removing excess cholesterol from peripheral vessels and transporting it back to the liver for elimination.
