Total blood cholesterol, serum cholesterol
This test measures the amount of cholesterol in your blood to help determine your risk for heart disease.
Cholesterol is a substance found in all of your body's cells, where it plays an important role. But your body can develop too much cholesterol if you eat the wrong types of foods, especially fried foods and foods with saturated or trans fats. Some medical conditions can also make your cholesterol level too high.
If you have too much cholesterol in your blood, it can stick to and inflame the walls of your arteries, leading to heart disease. Excess cholesterol helps cause narrowing of the vessels that bring blood to your heart muscles. This narrowing is called atherosclerosis. If your heart muscles don't get enough blood, you may be at risk for a heart attack.
The American Heart Association recommends that all adults ages 20 and older have their cholesterol checked once every five years.
You may have this test as part of your regular medical checkup. You may have this test done more often if you are at risk for heart disease or have other medical problems linked to high cholesterol.
Here are some common reasons for the test:
You have risk factors for heart disease, such as older age, obesity, family history of heart disease, high blood pressure, smoking, or diabetes.
You have a condition that may be closely linked to high cholesterol, including diabetes; alcoholism; and thyroid, liver, and kidney disease.
You eat a diet high in cholesterol and fats.
You may also have this test if you had high or borderline cholesterol on a previous blood test and your doctor is checking to see whether medication, diet, exercise, and other lifestyle changes are helping lower your cholesterol.
Your doctor may also order other blood tests to find out your HDL ("good") cholesterol, LDL ("bad") cholesterol, and triglyceride levels. This combination of blood tests is called a lipoprotein profile or a lipid profile.
Many things may affect your lab test results. These include the method each lab uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your health care provider.
Total cholesterol is measured in milligrams per deciliter (mg/dL). This is what your cholesterol number may mean:
Less than 200 mg/dL is a good number, and your risk of heart disease may be low.
200 mg/dL to 239 mg/dL is borderline high, and you may be at some risk for heart disease.
240 mg/dL or higher means your cholesterol is high and your risk for heart disease is higher than that of a person with normal cholesterol.
High cholesterol may be linked to these conditions:
Inherited diseases that cause high cholesterol
Gallbladder stonesKidney failure
Cancer of the pancreas or prostate
Low thyroid hormone
Cholesterol levels below 140 mg/dL may happen with:
Severe liver disease
High thyroid hormone
White blood cell cancers
Some types of anemia
Short-term illness or infection
Chronic lung disease
The test requires a blood sample, which is drawn through a needle from a vein in your arm.
Taking a blood sample with a needle carries risks that include bleeding, infection, bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight stinging sensation or pain. Afterward, the site may be slightly sore.
Your diet, age, alcohol use, and other lifestyle choices may affect your results. Many medications may also affect your results. Pregnancy may also affect your results. Having a heart attack in the last three months will also affect your results.
You should keep to your regular diet and avoid alcohol for at least two days before this test. You will be asked to not eat or drink anything but water for a certain amount of time before the test. This test is usually done in the morning after you fast overnight. If you take medications in the morning, ask your doctor whether you should take your pills.
In addition, be sure your doctor knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illicit drugs you may use.