Serum cholesterol, or total blood cholesterol, measures the amount of certain lipids in your blood. This blood test helps doctors determine your risk of developing heart disease in the next 10 years.

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Cholesterol is a type of fat, which is also called a lipid. It travels through your bloodstream in the form of tiny molecules wrapped inside proteins.

Your total blood, or serum, cholesterol measures three types of lipids:

  • low-density lipoprotein (LDL), or “bad” cholesterol, can cause plaque buildup in your arteries
  • high-density lipoprotein (HDL), or “good” cholesterol, prevents plaque buildup in your arteries
  • triglycerides

People often associate cholesterol with heart disease, as LDL cholesterol can build up in your arteries and restrict or block blood flow. However, your body still needs some cholesterol for healthy digestion, to make vitamin D, and to make certain hormones.

Keep reading to learn more about what doctors learn from your serum cholesterol level and how they measure it.

A health professional measures your serum cholesterol with a blood test known as a lipid panel. Before the blood draw, you need to fast for 8 to 12 hours.

During the test, a healthcare professional draws blood from your arm, enough to fill one or more small vials. Then, the samples are sent to a lab for analysis.

The frequency of this test depends on your age. The National Heart, Lung, and Blood Institute (NHLBI) recommends screening:

  • Children and young adults: Every 5 years
  • Females ages 55 to 65 years: Every other year
  • Males ages 45 to 65 years: Every other year
  • Adults ages 65 years and older: Every year

A doctor may recommend a lipid panel more often if you have certain risk factors for cardiovascular disease. These factors can include:

  • having overweight or obesity
  • smoking cigarettes
  • family history of heart disease
  • having a heart attack, stroke, or other cardiovascular event

If you start a new medication to manage your cholesterol or change medications, you’ll probably have more frequent cholesterol checks. Serum cholesterol tests can show how well the medication is working.

Your lab report shows your serum cholesterol levels in milligrams per deciliter (mg/dL).

The lower the LDL level and the higher the HDL level, the better. LDL is the type of cholesterol that forms waxy plaque on the inside wall of an artery. Too much plaque can limit blood flow through that artery.

HDL helps manage LDL cholesterol by moving LDL particles out of the bloodstream.

Higher levels of HDL are associated with better cardiovascular health. As for triglycerides, lower is better. When you eat, your body converts calories you don’t need for energy into triglycerides. Fat cells store the unused triglycerides. Consuming more calories than you burn will lead to weight gain and, often, higher triglyceride levels.

Here’s what to look for in your results of a fasting lipid panel:

Total cholesterolNon-HDL or LDLHDLTriglycerides
Optimal: Less than 200 mg/dLOptimal: below 100 mg/dLLow: below 40 mg/dL for malesOptimal: below 150 mg/dL
Borderline high: 200 to 239 mg/dLNear optimal: 100 to 129 mg/dLLow: below 50 mg/dL for femalesMild hypertriglyceridemia: 150 to 499 mg/dL
High: 240 mg/dL or higherBorderline high: 130 to 159 mg/dLOptimal: 40 mg/dL or greater for malesModerate hypertriglyceridemia: 500 to 886 mg/dL
High: 160 to 189 mg/dLOptimal: 50 mg/dL or greater for femalesVery high or severe hypertriglyceridemia: greater than 886 mg/dL
Very high: 190 mg/dL or greater High: 60 mg/dL or greater

Doctors calculate serum cholesterol by adding your HDL and LDL cholesterol levels and 20% of your triglycerides.

For example, if you have an LDL of 150 mg/dL, HDL of 35 mg/dL, and triglycerides of 180 mg/dL, your serum cholesterol would be 221 mg/dL. That’s considered a borderline high level. Your doctor may provide strategies and treatment to bring your numbers down.

If you have had a heart attack, stroke, or a stent placement, doctors may prescribe medications to lower your risk of future issues. This may include lowering your LDL to less than 55 mg/dL.

Treatment for high serum cholesterol focuses on:

Doctors commonly prescribe statins to lower cholesterol. Each type works a little differently in the body, but they all work to lower your LDL levels. Some may also improve HDL and triglyceride levels. This can reduce cardiac events and stroke.

You may have a higher risk of high cholesterol if you have a family history of high cholesterol. If this is the case, you may have high cholesterol even if you eat a heart-healthy diet and exercise regularly.

As you get older, your serum cholesterol also tends to go up.

Other risk factors for high cholesterol can include smoking cigarettes and having overweight or obesity.

You can typically manage high serum cholesterol with medication and lifestyle changes, such as increased exercise and dietary changes.

Cholesterol plaques can clog your arteries and raise your risk of heart attack and stroke.

If you have borderline high cholesterol levels, a doctor may recommend management strategies that can help lower your levels or keep them in an optimal range.

Doctors measure serum cholesterol levels to determine the amount of certain lipids in your blood. The results can indicate your risk of developing a cardiovascular disease. They can further help guide the treatment and management of high serum cholesterol levels.

Medications, such as statins, can help lower high cholesterol. They tend to be more effective in combination with other lifestyle changes.

If left untreated, high cholesterol can increase your risk of heart attack and stroke.