The LDL Cholesterol test measures the amount of low-density lipoprotein (LDL) in your blood. LDL is often called “bad cholesterol” because it can contribute to the buildup of fatty deposits (plaque) inside artery walls. Over time, plaque can narrow or block arteries (a process called atherosclerosis), increasing the risk of cardiovascular disease, including heart attack and stroke.

LDL cholesterol is usually reported in mg/dL (U.S.) or mmol/L (many other countries). In general, lower LDL levels are better for heart health, especially if you have other risk factors such as diabetes, high blood pressure, smoking, or a personal/family history of early heart disease. Your clinician interprets your LDL result in the context of your overall risk and may use it along with other values from a lipid profile (total cholesterol, HDL “good” cholesterol, and triglycerides) to guide a personalized plan.

Results are typically grouped into ranges such as “optimal,” “near optimal,” “borderline high,” “high,” or “very high.” The exact LDL target that’s best for you depends on your health history and risk category. For some people—especially those with known heart disease or diabetes—your care team may recommend more aggressive cholesterol management (dietary changes, physical activity, weight management, and/or medications like statins) to reduce future cardiovascular events.

The LDL cholesterol blood test is commonly ordered as part of routine preventive care or when evaluating cholesterol levels and heart attack risk. It may be done on its own, but more often it’s included in a lipid panel/lipid profile to assess overall cardiovascular risk.

Your clinician may recommend LDL testing if you:

• Are due for routine screening, especially in adulthood or if you have a family history of high cholesterol or early heart disease.
• Have risk factors for cardiovascular disease, such as high blood pressure, diabetes, smoking, overweight/obesity, physical inactivity, or chronic kidney disease.
• Have a personal history of cardiovascular problems (such as coronary artery disease, prior heart attack, angina, stroke, or peripheral artery disease) and need ongoing monitoring.
• Have signs that may suggest cardiovascular disease, such as chest pain/pressure, shortness of breath with exertion, or leg pain with walking (these symptoms require medical evaluation; the LDL test helps assess risk but does not diagnose an emergency).
• Are starting, changing, or monitoring treatment for cholesterol management (for example, after lifestyle changes or medications such as statins, ezetimibe, or PCSK9 inhibitors).
• Have conditions that can affect cholesterol, such as hypothyroidism, liver disease, kidney disease, or certain genetic lipid disorders.

Depending on the lab method and your situation, your test may be done fasting or non-fasting. If triglycerides are very high or if calculated LDL is being used, your clinician may ask you to fast for the most accurate interpretation.

• Atherosclerosis
• Coronary artery disease (CAD)
• Heart attack (myocardial infarction)
• Stroke (cerebrovascular disease)
• Peripheral artery disease (PAD)
• Hyperlipidemia / dyslipidemia
• Familial hypercholesterolemia (genetic high LDL)
• Metabolic syndrome
• Type 2 diabetes (increased cardiovascular risk and often abnormal lipid profile)
• Chronic kidney disease (often associated with higher cardiovascular risk)
• Hypothyroidism (can raise LDL cholesterol)

• Monitoring heart health and overall cardiovascular disease risk
• Checking and tracking cholesterol levels as part of a routine wellness exam
• Guiding diet and cholesterol changes (e.g., reducing saturated fat, increasing fiber, heart-healthy eating patterns)
• Supporting long-term cholesterol management plans, including weight management and exercise programs
• Assessing response to cholesterol-lowering medications and improving treatment adherence
• Preventing first-time or repeat cardiovascular events (heart attack and stroke prevention)
• Identifying possible inherited lipid disorders (e.g., familial hypercholesterolemia) for earlier intervention
• Helping clinicians tailor risk reduction strategies using a full blood test lipid profile and other risk factors