LDL cholesterol is a type of cholesterol in the blood that can indicate heart disease, and a blood test can measure the amount of LDL cholesterol in your blood. LDL cholesterol testing is usually done as part of a lipid panel test, which measures the amount of cholesterol and triglycerides in your blood. LDL cholesterol levels are typically reported in milligrams per deciliter (mg/dL) .

There are two types of LDL cholesterol tests: calculated LDL cholesterol testing and direct LDL cholesterol testing. In calculated LDL cholesterol testing, total cholesterol, HDL cholesterol, and triglycerides are used to estimate LDL cholesterol levels in your blood. Usually, LDL is calculated by subtracting the amount of HDL and VLDL from the total amount of cholesterol. In most cases, LDL cholesterol levels reported by your doctor are calculated rather than measured directly. Direct LDL cholesterol testing, on the other hand, measures only LDL cholesterol levels in your blood.

LDL cholesterol levels can provide information about cardiovascular health and may be measured as part of diagnosis, screening, or monitoring. A high LDL cholesterol level may indicate unhealthy levels of LDL cholesterol, which can cause the buildup of fatty deposits in your arteries and reduce blood flow, leading to heart disease or stroke. The optimal level for LDL cholesterol is generally less than 100 mg/dL, but this can vary depending on all your risk factors.