LDL stands for low density lipoprotein. Cholesterol cannot dissolve in the blood, so it must be transported by carriers, one of which is LDL. It takes cholesterol to be stored in the body. The other type of carrier is high density lipoprotein, or HDL, which takes cholesterol to be excreted. To protect against heart disease, the goal is to lower LDL and raise HDL. A simple blood test can reveal LDL and HDL levels.
Fast
The most accurate way to test LDL cholesterol levels is to have a fasting blood test, because levels can spike for hours after eating. Fasting provides a more accurate reading and a physician may want to know if LDL levels are high even when not eating. While each case is different, it is usually necessary to fast for between nine to 12 hours; a physician will provide individualized instructions. For some patients, it may also be necessary to stop taking certain medications.
Blood is Drawn
At a doctor's office, lab, or hospital, a small sample of blood is drawn from your arm. This only takes a few minutes, and the blood is then sent to a lab for analysis. It can take a few days or weeks to get results depending on the lab. A report will be provided for the doctor that shows your cholesterol level in milligrams per deciliter of blood, or mg/dL. In most cases, the test will also show total levels of cholesterol, HDL and triglycerides, which are another type of fat that circulates in the blood.
Friedewald Formula
To isolate LDL from the blood sample, a ultracentrifugation machine must be used. This machine spins the blood sample at a very high speed to separate particles in the blood; however, not all laboratories have this equipment. Those that do not have this machine use the Friedewald Formula to determine LDL levels. The formula used is [total cholesterol – HDL] – [the triglyceride level divided by five].
A Report is Generated
After the report is prepared, your physician will go over the results. If LDL is 130 mg/dL or more, it is considered high. At this stage, treatment is recommended because too much LDL in the blood can lead to plaque buildup along the blood vessel walls. This can cause a condition called atherosclerosis. If too much plaque builds up, the brain and heart may not get the blood and oxygen they need, which can lead to a stroke or heart attack. The treatment needed depends on how high LDL levels are and if there are any other risk factors for heart disease present.
