How Cholesterol Is Measured

Understanding Cholesterol Testing and What Results Mean

Among the most important measures of health are cholesterol levels. Cholesterol is a lipid that is carried in the bloodstream by specialized lipid-carrying particles called lipoproteins.

Cholesterol blood tests (often called the lipid panel) measure the amounts of cholesterol carried by three main lipoproteins—low-density lipoprotein (LDL), high-density lipoprotein (HDL), and very low-density lipoprotein (VLDL)—all of which play a role in cell metabolism. The lipid panel will also measure triglycerides, the most common type of fat in the blood.

Medical Lab technician hold sample blood for testing

Douglass Sascha / Getty Images

The amounts of LDL cholesterol, HDL cholesterol, VLDL cholesterol, and triglycerides in your blood will help your doctor assess your overall risk of heart disease, stroke, and other cardiovascular conditions.

The cholesterol test, then, is a critical part of the medical toolkit, which is why it’s important to understand how it works and what results mean.

What Does a Lipid Panel Measure?

As stated, when you have a lipid panel, there are several notable measurements. The results of your lipid panel are an important component in allowing your doctor to assess your cardiovascular health and risk. Other factors that are taken into account when determining your risk include your blood pressure, weight, exercise levels, and the presence of medical conditions such as diabetes.

Each component of the results provides different pieces of information. Important measures are:

  • Total cholesterol: The total cholesterol represents the total of all the cholesterol being carried by all the major lipoproteins in your blood. This measurement is generally not as useful in assessing your cardiovascular risk as the other cholesterol measurements made in the lipid panel.
  • LDL: LDL cholesterol is often called “bad” cholesterol because it’s the source of buildup and blockages in the arteries. Typically, there’s an elevation of health risks when these are too high.  
  • HDL: In contrast to LDL, you generally want higher levels of HDL, or “good” cholesterol. The HDL lipoprotein helps clear cholesterol from the bloodstream and takes it to the liver.
  • VLDL: Another type is VLDL cholesterol, a precursor to LDL that comes directly from food you eat. This type contributes to plaque buildup in the arteries and is considered “very bad.”
  • Non-HDL: The HDL score is subtracted from the total cholesterol measure to assess levels of the bad cholesterols, LDL and VLDL.
  • Triglyceride: Triglycerides are fats in the bloodstream that come from food. High triglyceride levels may be associated with metabolic syndrome and type 2 diabetes and can increase your cardiovascular risk independent of cholesterol levels. High levels here raise heart disease and type 2 diabetes risk and are of particular concern in women.
  • Cholesterol ratio: Also important is the ratio of total cholesterol to HDL. The lower the ratio, the lower your risk for heart or circulation problems, with 5:1 being targeted, and 3.5:1 considered ideal.

When you have a cholesterol test, doctors are most concerned with total cholesterol, HDL, LDL, and triglyceride levels.

How to Prepare for the Test

There’s not too much that goes into preparing for a cholesterol test. Whenever you go in for medical visit, it’s a good idea to come early and bring a list of any medications or supplements you’re taking. Wear comfortable and loose-fitting clothing so that you don’t put pressure on the site of collection when leaving. In addition, you may be asked to steer clear of any food or drink (aside from water) for 9–12 hours before the test.

Fasting and Cholesterol Tests

For many years, fasting prior to cholesterol tests was recommended in every case. However, increasingly, doctors are reconsidering this recommendation. Research suggests that food intake doesn’t affect the accuracy of measurements for total cholesterol, HDL, and LDL.

That said, food before a test can elevate triglyceride levels, so accuracy there does require fasting. Prior to your test, double-check with your doctor about how best to prepare.

Cholesterol tests provide a broader glimpse of your health status. You can’t really affect results without making significant, long-term dietary or lifestyle changes (or by taking medications). As such, behaviors like steering clear of foods high in cholesterol or saturated fat within a couple of days of your lipid profile won’t really affect results.

How the Test Is Performed

Cholesterol tests are performed on blood samples taken in a clinic, hospital, or outpatient center. This sample blood is usually collected from a vein in the forearm. You’ll feel a pinch when it’s being taken, and, from start to finish, the procedure typically only takes about five minutes.

A rapid test, which relies on blood collected from a finger prick, can also be given in the clinic or taken at home. These are typically not as accurate or detailed as their standard counterparts. 

After the Test 

Generally, the turnaround time for your results is relatively quick, only taking one to two days. Rapid test results from finger pricks are ready faster than that.

When you leave your appointment, you’ll have gauze or a bandage at the site of the blood draw. Some care needs to be taken to prevent bruising or hematoma, swelling, and pooling of the blood in the affected area. Here’s a quick breakdown:

  • Leave the bandage on for at least eight hours, but take it off within a day of your appointment.
  • Don’t take aspirin, ibuprofen (Motrin, Advil), or other nonsteroidal anti-inflammatory drugs (NSAIDs) for at least 72 hours.
  • Avoid lifting heavy objects or carrying bags or purses with the affected arm for several hours after the sample’s been taken.
  • Apply a cold pack or ice wrapped in cloth (if a hematoma has formed) for sessions of 20 minutes for 24 hours.
  • Apply warm compresses to the area if you’ve developed a hematoma and after the initial 24 hours of applying cold.

Though rare, some needlestick injuries and blood draw sites can become infected and problematic.

When Should You Call a Doctor?

Seek help if you see the following:

  • Your hand changes color.
  • The swelling worsens.
  • Pain, throbbing, or numbness are evident in the affected arm.

Interpreting the Results

Typically, you’ll have a consultation with your doctor about the results of your lipid panel. While each individual measure has its oen importance and place, a true assessment of health involves comparing them to each other, as well as assessing other health factors, such as disease status, lifestyle, genetics, gender, and age.

What sorts of measures raise red flags? There are several, including:

  • High total cholesterol: Because total cholesterol factors in both levels of unhealthy LDL and healthy HDL, this measure, on its own, may not be enough to determine cardiovascular risk. However, high levels here, along with high LDL, low HDL, and other risk factors for heart disease, prompt concern.
  • High LDL: If your score is above 100 milligrams per deciliter (mg/dL), you’re at a higher risk of developing heart diseases or blood vessel diseases like peripheral artery disease (PAD). Doctors may want those with other risk factors for these issues to have scores of 70 mg/dL or less.  
  • Low HDL: Insufficient “good cholesterol,” at 40 mg/dL or lower, is considered a risk factor for heart disease. In women, doctors want to see scores of 50 mg/dL or higher. LDL scores above 60 mg/dL reduce the risk of heart disease.
  • High triglycerides: When levels of this fatty acid are above 200 mg/dL, you’re at a higher risk for cardiovascular issues, such as heart attack and stroke. In addition, elevated triglycerides in the blood can be a sign of obesity or type 2 diabetes.   
Healthy and Unhealthy Cholesterol Levels
   Total  LDL HDL Triglyceride
Healthy Less than 200 mg/dL Less than 100 mg/dL 60 mg/dL and higher Less than 150 mg/dL
Borderline  200–239 mg/dL 130–159 mg/dL 40–59 mg/dL 151-200 mg/dL
High/Problematic 240 mg/dL and above 160–189 mg/dL Less than 40 mg/dL 201-499 mg/dL
Very High 190 mg/dL and above 500 mg/dL and above
A Breakdown of healthy, borderline, and problematic levels of cholesterol

What Are Normal Blood Cholesterol Levels? 

Cholesterol levels, measured in milligrams (mg) of cholesterol per deciliter (dL) of blood, are categorized as optimal, near optimal, borderline, high, and very high. What are considered healthy, normal levels?

While individual health factors can influence what’s considered healthy, typically doctors want to see:

  • Total: For people 19 and younger, less than 170 mg/dL is healthy. This number becomes a range of 125-200 mg/dL in men and women 20 and older.
  • Non-HDL: Nineteen-year-olds and younger should have less than 120 mg/dL of this type, and this figure jumps to 130 mg/dL for adults.
  • LDL: In men and women 20 and up—as well as those younger—levels smaller than 100 mg/dL are considered within a healthy range.
  • HDL: Those 19 and younger should have an HDL of greater than 45 mg/dL. In adult men, this figure should be at least 40 mg/dL, with the healthy range climbing to 50 mg/dL or higher for women.

A Word From Verywell

Clearly, your cholesterol levels are closely tied to your health, and understanding your numbers as well as where you should be, is an important step in taking care of yourself. If you don’t know your cholesterol levels, ask your doctor when you should get tested. And if your scores aren’t where they should be, know that, while it may take effort, your measurements can definitely be managed. Whatever challenges you face, the benefits—a longer, healthier life—are worth it.

Frequently Asked Questions

  • Are there any foods I should avoid before a cholesterol test?

    If your doctor wants you to fast before the test, you’ll have to steer clear of all foods for up to 12 hours beforehand. However, researchers have found that eating most foods only negligibly affects most cholesterol measures—total, HDL, and LDL—with only triglycerides seeing spikes for a couple hours after a meal.

  • How long do I need to fast before a cholesterol test?

    Typically, patients are asked to avoid eating food or any beverage aside from water for nine to 12 hours before the test. For some kinds of cholesterol—and for younger people—fasting may not be necessary, so make sure you have a clear sense of what your doctor needs you to do.

  • What happens if I don’t fast before a cholesterol test?

    While fasting before cholesterol has been the standard practice, it may not be necessary in every case. In fact, researchers have noted that eating beforehand has only a negligible effect on three of the four primary types: total, HDL, and LDL.

    However, food before a test can cause triglyceride levels to spike significantly. If testing without fasting reveals these to be too high, another lipid panel will be ordered.   

  • Can you test your cholesterol at home?

    Since cholesterol levels can play such a critical role in health, it may be tempting to purchase home testing kits. With just a sample of blood, these have the advantage of providing convenient and rapid results. In ideal situations and if used correctly, cholesterol testing kits approved by the Food and Drug Administration are about as accurate as clinical tests. However, there are limitations on how useful they are. Talk to your doctor if you’re thinking about at-home testing.

  • How accurate are at-home cholesterol tests?

    Though very convenient and easy to use, there are a number of drawbacks to at-home cholesterol tests. They can yield accurate measures, but these alone often aren’t able to tell you the information you need to know. Notable issues with these include:

    • Uncontrolled conditions: In the clinic, doctors, medical staff, and clinicians employ specific methods to ensure they collect a good, usable sample. If too much blood is collected, or if it’s collected improperly, results of at-home testing kits can be thrown off.
    • Missing panels: Most at-home kits are only able to provide measures of total cholesterol, which by itself is not enough to give you a total picture of cardiovascular health and risk.  
    • Lacking analysis: Even if kits are able to test for other types of cholesterol, they may report results in terms of general, national guidelines. While that can be helpful, it doesn’t take into account factors that your doctor can, such as your other health conditions and factors.
  • How often should cholesterol be tested?

    Barring any health issues, people 20 and younger should be tested once every five years, with the first panel taken between ages 9 and 11. Healthy men between 20 and 45 and women between 20 and 55 should also have their cholesterol checked every five years. Older men 45 and up and women 55 and up require more frequent assessments: every one to two years.

    However, those with certain health conditions, such as heart disease or a family history of high cholesterol, may require more frequent assessments.

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10 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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