What does “low high-density lipoprotein (HDL)” mean?

High-density lipoprotein (HDL) is one of the serum proteins. It is a complex lipoprotein composed of lipids, proteins, and associated regulatory factors. Because HDL facilitates cholesterol efflux and promotes cholesterol metabolism, it is recognized as a key protective factor against atherosclerosis. So, what does low HDL mean? The following section addresses this question.

HDL transports cholesterol from peripheral tissues to the liver, where it is either converted into bile acids or excreted directly via bile into the intestine. Angiographic studies have demonstrated a significant inverse correlation between HDL cholesterol levels and the degree of arterial lumen narrowing. Thus, HDL is an anti-atherosclerotic plasma lipoprotein and serves as a protective factor against coronary heart disease. Low HDL levels suggest an increased risk of cardiovascular and cerebrovascular diseases—including cerebral infarction, cerebral thrombosis, myocardial infarction, angina pectoris, and atherosclerosis. Therefore, patients are advised to maintain a balanced diet, engage in regular physical activity, and avoid excessively fatty foods. When necessary, drug therapy may be prescribed under medical supervision.

Knowledge Extension: Health Risks Associated with Hyperlipidemia

1. Induction of Hypertension

Hyperlipidemia promotes atherosclerosis, leading to myocardial dysfunction, massive activation of angiotensin-converting enzyme, arterial vasoconstriction, and stimulation of adrenal secretion of pressor hormones—ultimately resulting in elevated blood pressure. Once hypertension develops, persistent vascular spasm occurs. In addition, cerebral vessels—already hardened and with damaged endothelium—are prone to rupture, causing hemorrhagic stroke.

2. Induction of Coronary Artery Disease (CAD)

Coronary artery disease—also known as coronary atherosclerotic heart disease—involves the arteries that supply oxygen-rich blood to the heart muscle. Excessive fat deposition leads to arterial hardening and stenosis, impairing blood flow and triggering ischemic cardiac events. CAD is thus a major complication of hyperlipidemia. Accordingly, controlling lipid levels is recommended to reduce the incidence of CAD, angina pectoris, and myocardial infarction.

3. Cellular Damage

Excess free and deposited lipid substances in the bloodstream increase systemic oxygen demand and generate lipid peroxidation-derived free radicals via oxidative reactions. These free radicals circulate in plasma and damage cells, causing cell death and senescence—contributing to accelerated aging and impaired cellular function.

The above explains what low HDL cholesterol signifies. We hope this information is helpful to you.