Understanding LDL, HDL and Triglycerides This Cholesterol Education Month

September is National Cholesterol Education Month, a good time to make sense of the three numbers on a standard cholesterol test. LDL, HDL and triglycerides are often lumped together, but they do different jobs in the body and carry different meanings for heart health.

What a cholesterol test measures

A cholesterol check, also called a lipid panel or lipid profile, usually measures cholesterol and triglycerides in the blood, and results are reported in milligrams per deciliter (mg/dL). Cholesterol travels through the bloodstream inside particles called lipoproteins. The two main types are low-density lipoprotein (LDL) and high-density lipoprotein (HDL). Total cholesterol is calculated by adding HDL, LDL and 20% of the triglyceride level.

LDL: The particle tied to plaque in the arteries

LDL is often called “bad” cholesterol because it can build up in the arteries over time, increasing the risk for heart attack, stroke and peripheral artery disease. Family history, including inherited conditions such as familial hypercholesterolemia, a diet high in saturated fat, low physical activity, excess weight and tobacco use can all contribute to high LDL.

There is no single “normal” LDL number that fits everyone. The American Heart Association says a person’s goal depends on factors such as age, overall health, family history, diabetes, and any history of heart attack or stroke. For some people the goal may be below 100 mg/dL, while for those at very high risk it may be 70 or 55 mg/dL.

HDL: Helpful, but not a number to chase

HDL carries LDL cholesterol away from the arteries and back to the liver, where it is broken down and passed from the body, though HDL does not eliminate all LDL. Higher HDL levels are linked to a lower risk of heart attack and stroke, but the “good” label can be misleading. The American Heart Association says HDL is not a primary treatment target and should not be interpreted on its own, though clinicians still weigh it alongside other risk factors. Regular physical activity, a healthy weight, avoiding tobacco, and a diet rich in vegetables, fruits and whole grains can help support healthy HDL levels.

Triglycerides: Stored energy in the same blood draw

Triglycerides are a different substance from cholesterol. They are the most common type of fat in the body and store excess energy from the diet. A level below 150 mg/dL is usually considered normal, and high triglycerides matter most for heart health when combined with high LDL or low HDL. Levels can rise with age or weight gain, physical inactivity, smoking, heavy drinking, and a diet heavy in refined carbohydrates such as white flour or white rice.

How testing and guidelines are shifting

For most adults, the American Heart Association says cholesterol screening every five years starting at age 19 works well, and a clinician can adjust the schedule based on individual risk. Screening is also recommended for children ages 9 to 11 who have not been tested.

The guidance itself is evolving. In March 2026, the American College of Cardiology, the American Heart Association and nine other medical associations issued an updated dyslipidemia guideline, noting that about one in four 4 U.S. adults has high LDL cholesterol. It replaces the 2018 guideline and emphasizes earlier intervention through healthy lifestyle changes starting in childhood. LDL and non-HDL cholesterol treatment goals are back in the guidance. The guideline also recommends measuring lipoprotein(a), another inherited risk marker, at least once.

A health care professional can explain what a person’s own results mean in the context of their overall risk.

This article is for education and is not a substitute for medical advice.