LDL cholesterol describes cholesterol bound by low-density lipoprotein -- a specialized protein consisting of proteins on the outer layer and fats and cholesterol in the inner layer. The function of the lipoprotein is to carry cholesterol through the blood so it can reach cells throughout the body. Too much cholesterol in the blood promotes the formation of plaque, a hard substance consisting of cholesterol, calcium, fat and other waste products, which restricts the flow of blood and leads to heart disease. To assess your risk for heart disease, monitor your cholesterol levels through routine blood tests that can determine your LDL cholesterol levels.
Test Procedure
To perform a cholesterol test, your doctor removes a sample of blood from a vein or through a finger stick. A standard lipid profile test provides results for the total blood cholesterol, HDL cholesterol and triglycerides. Although it does not directly determine the LDL cholesterol level, doctors can calculate it using the total cholesterol -- which includes all types of cholesterol and HDL cholesterol, the other major type of cholesterol. To test specifically for LDL cholesterol, doctors must perform the Direct LDL-C blood test. For accurate results, you must fast, which means refraining from consuming any food or drink other than water, for at least 12 hours prior to giving the blood sample.
Test Results
In the United States, the LDL cholesterol test is reported as the number of milligrams of cholesterol per deciliter of blood. In Canada and Europe, the millimoles of cholesterol per liter of blood is measured. When interpreting your LDL cholesterol level, you must take into account your overall risk for heart disease. Additional risk factors include the presence of heart disease, diabetes, high blood pressure, low HDL cholesterol, family history and smoking.
Interpreting LDL Levels
In general, doctors recommend you aim to keep your LDL cholesterol levels under 100 mg/dL. However, the range for healthy LDL levels depends upon the other heart disease risk factors. Patients suffering from heart disease should keep their LDL cholesterol under 70 mg/dL, according to the Harvard Medical School Family Health Guide. Patients with two or more risk factors, such as high blood pressure and diabetes, should keep their LDL cholesterol to under 130 mg/dL. A healthy patient with no other heart disease risk factors can have an LDL cholesterol level up to 160 mg/dL and still be classified as a low risk for heart disease.
Significance
The LDL cholesterol level is the most important when it comes to assessing your risk for heart disease. In addition, doctors determine the appropriate treatment based off the result of the LDL cholesterol test. So although a standard lipid profile can estimate the LDL level, results that show higher-than-normal levels should prompt your doctor to perform the LDL cholesterol test. For those undergoing treatment to lower your cholesterol levels, LDL cholesterol tests help you monitor your progress.
