Interpreting Blood Cholesterol Test Results

Interpreting Blood Test Results

Blood cholesterol levels are measured in a small blood sample taken from a finger prick, or from a vein in your arm. The blood is tested for total cholesterol, and, if accurate results can be obtained, HDL-cholesterol levels. You do not have to fast before having this blood test.

Depending on the results, you may also need a second blood test, a Lipoprotein Profile, to determine your LDL-cholesterol level. You do have to fast for this test. An LDL-cholesterol level gives the doctor more information about your risk of heart disease, and helps to guide any necessary treatment.

Cholesterol levels are measured in milligrams per deciliter (mg/dL). The National Cholesterol Education Program developed the following classifications:

For people over age 20 who do not have heart disease...

  • Desirable Blood Cholesterol --Total blood cholesterol level less than 200 mg/dL. HDL level 35 mg/dL or greater.
    LDL level less than 130 mg/dL.

If your blood cholesterol levels fall into this category, you are doing well and should have your total and HDL cholesterol levels checked again in about five years. In the meantime, take steps to keep your total cholesterol level down by eating foods low in saturated fat and cholesterol, maintain a healthy weight, and exercise regularly.

  • Borderline-High Blood Cholesterol --Total blood cholesterol level between 200 and 239 mg/dL.
    LDL level between 130 and 159 mg/dL.

If your total blood cholesterol level is less than 240 mg/dL and your HDL level is less than 35 mg/dL, you will also need a Lipoprotein Profile to determine your LDL level. If your total blood cholesterol level is between 200 and 239 mg/dL, and your HDL level is 35 mg/dL or greater, your doctor will check other risk factors for heart disease, and determine whether a Lipoprotein Profile is needed. If your blood cholesterol levels fall within this category, it is very important to eat foods low in saturated fat and cholesterol, and to maintain physical activity.

  • High Blood Cholesterol -- Total blood cholesterol level greater than 240 mg/dL, or LDL level greater than 160 mg/dL.

If your blood cholesterol levels fall within this category, and fewer than two other risk factors for heart disease are present, the goal is to lower your LDL level below 160 mg/dL. If your blood cholesterol levels fall within this category, and two or more risk factors for heart disease are present, the goal is to lower your LDL to less than 130 mg/dL.

For people who have heart disease...

You are said to have Coronary Heart Disease if you have suffered any of the following:

  • Heart attack
  • Chest pain (which has been diagnosed as angina)
  • Heart surgery (such as bypass operation, balloon, or angioplasty procedure)
  • Build-up or blockage in any arteries

If you have heart disease, you will need to have a blood test called a Lipoprotein Profile. This test will determine not only your total and HDL-cholesterol levels, but also your LDL-cholesterol level and levels of another fatty substance called triglyceride. In order to take the test you must fast (which means you can have nothing to eat or drink but water, or coffee or tea with no cream or sugar for 9-12 hours beforehand).

A person with coronary heart disease has a much greater risk of having a future heart attack than a person without heart disease. If you lower your blood cholesterol level, you can definitely reduce your risk of future heart attacks and may, in fact, prolong your life.

  • Increased Risk -- LDL level greater than 100 mg/dL. HDL level less than 35 mg/dL.

If your LDL level falls within this category, you will need to have a complete physical examination to see if you have a disease or a health condition that is raising your cholesterol levels. You will need a diet that is lower in saturated fat and cholesterol; you may need to lose weight if you are overweight; and you must quit smoking (if you smoke). If your LDL levels still remain high after making the recommended lifestyle changes, you may need to take a cholesterol-lowering medicine.

If your LDL level is 100mg/dL or less, you will not need to take specific steps to lower your LDL level. You will, however, need to have your level tested again in one year, follow a diet low in saturated fat and cholesterol, maintain a healthy weight, be physically active, and not smoke.

What is a Cholesterol Ratio?

Some laboratories may calculate a Cholesterol Ratio. The ratio is obtained by dividing either total cholesterol or LDL-cholesterol by the HDL-cholesterol. The ratio is not recommended since it is more important to know each value separately. Be sure to get separate total cholesterol, LDL, and HDL values.

What are Triglycerides?

Triglycerides are a form of fat that is carried through the bloodstream. Most of your body's fat tissue is in the form of triglycerides. High blood triglyceride levels alone usually do not raise your risk of heart disease. But many people have a high triglyceride level along with high LDL- and low HDL-cholesterol levels. In these cases, the three are often treated together.

Here's how to judge your triglyceride level:

  • Normal -- Triglyceride level less 200 mg/dL.
  • Borderline-High -- Triglyceride level between 200 and 400 mg/dL.
  • High -- Triglyceride level between 400 and 1000 mg/dL.
  • Very High -- Triglyceride level greater than 1,000 mg/dL.

Borderline-high and high triglyceride levels are first treated with the same diet and lifestyle changes used for high blood cholesterol levels. These changes include losing weight if you are overweight; following a diet low in saturated fat and cholesterol; being physically active; and not smoking.

Usually, high triglyceride levels are due to heredity, and levels may need to be lowered with medicines.

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