A lipid panel is a group of tests that measure your cholesterol and triglyceride levels. Doctors order it to get an idea of your risk of heart disease. Read on to learn how to prepare for the test, what your results mean, and how doctors interpret high levels.
What is a Lipid Panel?
Lipids are a group of fat-like compounds that serve many important functions in the body. A lipid panel, or lipid profile, measures the amount of the two main lipids in your blood: cholesterol and triglycerides.
Cholesterol is a waxy substance needed to make hormones, bile acids, and vitamin D. It also helps provide structure and fluidity to cell membranes. You can get cholesterol from your diet as it’s found in many animal products. However, it’s so vital for your health that your body produces it naturally [1].
Triglycerides are the main component of body fat but they also circulate around the body and can be used as an alternative source of energy to glucose. Triglycerides come from the diet but they are also made by the liver [2].
Because cholesterol and triglycerides are insoluble in water and your blood is water-based, they must be carried around by special compounds made of fat and proteins called lipoproteins [3].
Most people are familiar with the lipoproteins LDL and HDL. When you get your lipid levels checked, the test measures the amount of cholesterol and triglycerides being carried around by these lipoproteins, not the amount of lipoproteins themselves.
You can think of lipoproteins as cars on a highway (your blood vessels) and the cholesterol and triglycerides as the passengers. A standard lipid panel measures the number of passengers, not the cars themselves.
Why Is It Important?
Heart disease is currently the leading cause of death worldwide [4].
Although cholesterol is vital to your health, too much of it contributes to heart disease [5].
High cholesterol levels can be caused by genetics, diet, lack of exercise, medications, as well as certain diseases such as diabetes and hypothyroidism [1].
Cholesterol can become dangerous when it enters the walls of your vessels and oxidizes. Once inside the blood vessel walls, immune cells called macrophages target and engulf the oxidized cholesterol. When macrophages become filled with cholesterol, they form fatty plaques that lead to hardened arteries [5].
Over the course of many years, this eventually causes heart disease which may result in a heart attack or stroke [5].
This means that testing your lipid levels is a very important part of reducing your risk for heart disease [6].
Doctors use the results of your lipid panel in combination with other important risk factors to determine your overall risk for heart disease. These risk factors include [6, 7]:
- Age
- Sex (men tend to get heart disease 7 to 10 years earlier than women)
- Family history of heart disease
- High blood pressure
- Smoking
- Diabetes
- Obesity
Doctors also the lipid panel in order to monitor the effects of lifestyle interventions and cholesterol-lowering medications (statins) in patients [6].
In children and adolescents, a lipid panel can help detect genetic diseases such as familial hypercholesterolemia, which causes dangerously high cholesterol levels. These diseases are often lethal if not treated early [8].
What Does it Test For?
A standard lipid panel typically measures four different types of lipids:
- Total cholesterol (TC)
- Low-density lipoprotein cholesterol (LDL-C)
- High-density lipoprotein cholesterol (HDL-C)
- Triglycerides (TG)
From these values, the lab can also calculate your:
- Very low-density lipoprotein cholesterol (VLDL-C)
- Cholesterol to HDL-C ratio
- Non-HDL-C
Some expanded lipid panels may include measurements of lipoprotein(a) and apolipoprotein B (apoB), as well as lipoprotein size and number (counting the number of cars instead of passengers) [9].
Lipoprotein(a) levels are mainly determined by genetics and high levels are independently linked to heart disease [9].
ApoB is a measurement of the total amount of non-HDL lipoproteins (LDL, IDL, and VLDL). Non-HDL lipoproteins all have the potential to cause hardening of the arteries that leads to heart disease [9].
In terms of lipoprotein size, small dense LDL particles are associated with a greater risk of heart disease than larger LDL particles [10].
Expanded panels are mainly used in people who are at a very high risk of heart disease due to genetics [9].
They’re also used in people who continue to experience high cholesterol levels and cardiac events despite being on statins [9].
Total Cholesterol
Total cholesterol is just the total amount of cholesterol in the blood. It is a combination of LDL-C, VLDL-C, and HDL-C.
Higher total cholesterol levels are linked to an increased risk of heart disease [11].
LDL Cholesterol
LDL-C is known as “bad cholesterol” because it can become lodged in the walls of blood vessels and cause fatty plaques and hardened arteries [5].
As you would expect, high levels are strongly linked to heart disease [12].
LDL-C isn’t usually measured directly but instead is calculated using a formula that takes into account your triglycerides, total and HDL cholesterol [9].
VLDL Cholesterol
VLDL-C is also considered “bad cholesterol” because it can become lodged in blood vessel walls and contribute to plaque formation [5].
Like LDL-C, it can cause hardening of the arteries and higher levels are linked to an increased risk of heart disease [13].
VLDL-C is usually not measured directly but is instead calculated using your triglyceride levels [14].
You can calculate your VLDL-C by simply dividing your triglycerides value by 5 if it is in mg/dL. If your triglycerides value is in mmol/L, then divide by 2.2 [14, 9].
HDL Cholesterol
HDL-C is known as the “good cholesterol” because it counteracts the effects of LDL-C by removing cholesterol from blood vessel walls and taking it to the liver to be removed [15].
As a result, higher levels are linked to a decreased risk of heart disease [16].
Triglycerides
Triglycerides don’t cause heart disease directly but high levels are linked to an increased risk of heart disease due to their association with high VLDL-C levels [17].
Very high levels (> 1,000 mg/dL) can also increase the risk of an inflamed pancreas (pancreatitis) [18].
How Often Should You Get a Lipid Panel?
Doctors generally agree that lipid testing should begin no later than age 40 for men and 50 for women [19].
Because lipids levels don’t change substantially over the long term, a lipid panel only needs to be done once every 5 years in healthy people [19].
If you are at a high risk of heart disease (due to factors such as genetics, obesity, diabetes, smoking or high blood pressure) or your doctor needs to monitor treatment, you should get a lipid panel done more frequently [19].
The American Academy of Pediatrics recommends screening all children and adolescents once between the ages 9 and 11 years and again at ages 17 to 21 years to identify those with familial hypercholesterolemia [20].
Lipid Panel Blood Test
Preparation and Procedure
A lipid panel usually requires that you have your blood drawn and sent to a lab for testing [6].
In most cases, you will need to fast overnight for 8 to 12 hours (only water is allowed) before giving a blood sample [6].
Depending on the lab, you may get your results that same day.
Before taking the test you should tell your doctor about any medications or supplements you are taking as well as any current health issues or symptoms you may be having. You should also let your doctor know if you have a family history of heart disease.
Fingerstick Tests
There are also tests that you can take at your doctor’s office which only require a blood sample from a finger prick. Fingerstick tests give you results within minutes, allowing your doctor to give you immediate feedback [21].
These tests also require you to be in a fasted state before giving a blood sample [22, 23, 24].
In most people, fingerstick tests are almost as accurate as lab tests that require blood draws [22, 25, 23, 24].
However, they are not accurate in older people with high cholesterol levels (LDL-C greater than 140 mg/dL), who are at a much higher risk of heart disease due to their age [26].
Fingerstick tests should only be used to check for abnormal lipid levels and should not be used as a basis for treating high cholesterol levels or prescribing medication [26].
It is especially important to properly clean the finger well enough before taking a blood sample to prevent inaccurate results [25].
Fasting vs. Non-fasting Lipids
You can also have your lipids tested in a non-fasting state [27].
Nonfasting lipid testing is becoming more popular and many countries are currently changing their guidelines to make nonfasting testing the clinical standard [9].
This is due to a lack of evidence supporting fasting testing as a better method for predicting heart disease risk [9].
In fact, research suggests nonfasting triglycerides are actually a better predictor of heart disease risk than fasting triglycerides [28, 29, 30].
This may be because most people eat regularly throughout the day so nonfasting triglycerides may better represent average levels in the blood [17, 28, 29].
There are also other advantages to nonfasting lipid testing, such as [9, 27]:
- Being more convenient for the patient, which means they are more likely to get a lipid panel done
- Being more convenient for the lab, because they are not overwhelmed with early morning blood samples
- Reducing the risk of low blood sugar from fasting in diabetes patients
Nonfasting tests are especially important for diabetic patients because it can reveal high triglyceride levels that may otherwise go unnoticed after fasting [27].
The main reason fasting has been the clinical standard is due to studies showing that triglyceride levels increase substantially in the hours following a fat-rich meal [31, 32].
This led to the thinking that triglyceride measurements and calculated LDL-C (which relies on triglycerides) would be inaccurate following any type of meal [27].
However, these studies used meals containing abnormally high amounts of fat (2.2 g fat/lb), designed to see how high a patient’s lipids rose in response (fat tolerance test) [31, 32].
In other words, they don’t apply to a normal meal consumed by most people [27].
A normal meal only increases triglycerides slightly. Total cholesterol, LDL-C, and HDL-C levels actually decrease slightly or do not change after a normal meal [29, 33, 34, 35].
How to Prepare for a Nonfasting Lipid Test
If you do get a nonfasting lipid test, you should avoid eating high-fat meals beforehand [27].
If your nonfasting triglycerides are above 440 mg/dL (> 5 mmol/L), then a fasting test may be needed to rule out the effect of food [27].
Fasting samples may also be required in people taking medications that cause very high triglyceride levels, such as tamoxifen (used to treat breast cancer) [27, 36].
What Do Your Results Mean?
Understanding the Units
Your results will be measured in either mg/dL or mmol/L, depending on the lab that performed the test and the country in which you live.
To convert total cholesterol, HDL-C, and LDL-C values between units:
- Divide mg/dL value by 38.7 to get mmol/L
- Multiply mmol/L value by 38.7 to get mg/dL
To convert triglycerides between units:
- Divide mg/dL value by 88.6 to get mmol/L
- Multiply mmol/L value by 88.6 to get mg/dL
Results Interpretation & Normal Values
Most doctors will use the following established ranges to evaluate heart disease risk and guide patient treatment [6]:
Total Cholesterol
- Optimal: < 200 mg/dL (< 5.18 mmol/L)
- Borderline high: 200 – 239 mg/dL (5.18 – 6.18 mmol/L)
- High: > 240 mg/dL (> 6.18 mmolL)
LDL-C
- Optimal: < 100 mg/dL (< 2.59 mmol/L)
- Near optimal: 100-129 mg/dL (2.59-3.37 mmol/L)
- Borderline high: 130-159 mg/dL (3.37-4.12 mmol/L)
- High: 160-189 mg/dL (4.15-4.90 mmol/L)
- Very high: > 189 mg/dL (> 4.90 mmol/L)
Note: When calculated LDL-C is below 70 mg/dL and triglyceride levels are between 150-399 mg/dL, the calculation may underestimate actual LDL-C levels by 9 to 19 mg/dL [37].
In these patients, directly measuring LDL-C levels is important given their increased risk of heart disease due to high triglyceride levels [37].
Calculated LDL-C levels become very inaccurate when triglyceride levels are above 400 mg/dL (4.5 mmol/L) and should always be directly measured [38].
HDL-C
- High risk: < 40 mg/dL (< 1.0 mmol/L) for men or <50 mg/dL (< 1.3 mmol/L) for women
- Average risk: 40-50 mg/dL (1.0-1.3 mmol/L) for men and between 50-59 mg/dl (1.3-1.5 mmol/L) for women
- Optimal: >60 mg/dL (> 1.55 mmol/L)
VLDL
- Optimal: < 30 mg/dL (< 0.77 mmol/L)
- High: >30 mg/dL (> 0.77 mmol/L)
Triglycerides
- Optimal: < 90 mg/dL (< 1 mmol/L)
- Normal: < 150 mg/dL (< 1.7 mmol/L)
- Borderline high: 150 – 200 mg/dL (1.7 – 2.3 mmol/L)
- High: 200 – 500 mg/dL (2.3 – 5.6 mmol/L)
- Very high: > 500 mg/dL or above (>5.6 mmol/L)
There are no established ranges for non-fasting testing but given the minimal effect of meals on lipids, the ranges for fasting lipids may be used [19].
If one or more of your lipids are abnormal, you are at an increased risk of developing heart disease [6].
Your doctor may order additional tests such as a blood sugar or thyroid function test to determine the cause of your high cholesterol levels [39, 40].
Treatment Options
Diet & Lifestyle
If your cholesterol or triglyceride levels are abnormal and you don’t have any other risk factors, your doctor will usually recommend diet and lifestyle changes first before prescribing you medication. These may include [41]:
- Losing weight
- Exercising more
- Avoiding smoking
As for diet, your doctor may advise you to [41]:
- Reduce your saturated and trans fat intake
- Eat less sugar
- Eat more fruits and vegetables
Medications
If your levels remain high even after diet and lifestyle changes or you also have other risk factors for heart disease, your doctor may prescribe a statin.
Other cholesterol-lowering medications that your doctor may prescribe include [41]:
- Fibrates (Fenofibrate)
- Bile acid sequestrants (Cholestyramine)
- Ezetimibe
In most cases, these medications are used in patients who don’t respond to or can’t tolerate statins [41].
You should talk to your doctor about the risks and benefits of statins and other cholesterol-lowering medications.
All in all, high cholesterol levels are the most manageable risk factor for heart disease. By adhering to your treatment plan and staying informed you can ensure the best outcome for your heart health.
Takeaway
A lipid panel is a group of tests that measure your cholesterol and triglyceride levels. By looking at your lipid panel in combination with other risk factors, doctors can determine your overall risk for heart disease. Usually, you need to fast for at least 8 hours overnight and only drink water before getting your lipids tested.
Nonfasting testing is also rising in popularity and becoming a valid method for testing lipid levels as studies suggest it may have advantages over fasting testing. Your results, along with any other risk factors you have, will inform doctors on possible treatment options.
If your levels are high, your doctor will suggest you make diet and lifestyle changes such as exercising more, losing weight, and eating less saturated fat and sugar. If you have high levels in addition to other risk factors for heart disease, your doctor may prescribe medication to help lower your cholesterol levels.
