How and when to test for hyperlipidemia in clinical practice

Treating lipid disorders in high-risk patients significantly reduces their likelihood of a cardiovascular event—but did you know screening thresholds differ by sex, age, and risk profile? The measures you request and how you use them will give you a clear picture of your patient's cardiovascular risk.

In this lesson from our Hyperlipidemia Essentials course you’ll learn how to:

• Identify who to test for hyperlipidemia and when
• Select the right measures for a lipid panel
• Decide when a fasting lipid panel is necessary
• Use a cardiovascular risk calculator to estimate 10-year CVD risk
• Stratify patients into four cardiovascular risk categories

Why test for hyperlipidemia?

[00:00]

Understanding the connection between elevated LDL levels and the risk of cardiovascular disease is essential, because treating lipid disorders in patients at high risk significantly reduces their likelihood of experiencing cardiovascular events. 

Global differences in lipid screening

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However, the approaches to assessing and managing risk can vary widely between countries. For example, while many countries use risk calculators to guide treatment, these often overlook key predictors like LDL, ApoB and Lp(a), which are among the strongest indicators of risk. Additionally, the use of cardiac CT imaging for screening is becoming more common, though its availability differs across regions. While screening approaches differ globally, this lesson focuses on guidelines and practices commonly used in the United States. 

Who to test for hyperlipidemia

[00:56]

So who should be screened for hyperlipidemia? For individuals without known risk factors, routine screening should start at age 35 for males and age 45 for females. Patients with known risk factors should be screened earlier. For males, screening should be between ages 25 and 30 and for females, it should be between ages 30 and 35. Several risk factors increase CVD risk, including being male, aging, hypertension, diabetes, smoking, obesity, a sedentary lifestyle and a family history of premature CVD.

Family history considerations

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A family history is defined as having a first-degree male relative diagnosed before age 55 or a first-degree female relative diagnosed before age 65. All adults should be screened whenever they begin care with a new primary care provider.

When to repeat a lipid panel

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If the results are normal, meaning LDL cholesterol is below 100 mg / dL and triglycerides are below 150 mg / dL, rescreening every five years is sufficient. Patients with LDL levels near treatment thresholds, typically between 100 and 160 mg / dL, depending on other risk factors, should be rescreened every three years. Lipid levels tend to drop in older adults, so screening can stop at age 65 for those with consistently normal results. 

What to include in a lipid panel

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Now, which blood tests are used for lipid screening? A full lipid profile is essential. This includes total cholesterol, low density lipoprotein, or LDL, high density lipoprotein, or HDL, and triglycerides. It's important to measure apolipoprotein B, or ApoB, and lipoprotein(a), or Lp(a), which are stronger predictors of cardiovascular risk.

Fasting vs. non-fasting

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While most laboratories recommend fasting for lipid tests, cholesterol levels don't change much between fasting and non-fasting states. However, non-fasting triglyceride levels are more predictive of cardiovascular events. Patients at higher risk for hypertriglyceridemia include those who are overweight, have type 2 diabetes, consume significant amounts of alcohol, or take medications known to raise triglyceride levels, like steroids. For patients with hypertriglyceridemia or a family history of genetic hyperlipidemia, fasting lipid profiles should always be performed initially. 

Estimating cardiovascular risk

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Once we have the lipid profile results, we can estimate cardiovascular risk for patients needing primary prevention using a risk calculator. There are multiple risk models, but not all will suit all patients. You will want to select a CVD risk calculator from the course handbook that is most appropriate for the patient population in your geographic region. Risk calculators incorporate risks like age, sex, race, total cholesterol, HDL, blood pressure, diabetes, family history of premature CVD and smoking status. 

Risk calculators by region

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In the United States, the American College of Cardiology and the American Heart Association use the Prevent Calculator. Across Europe, including the United Kingdom, the European Society of Cardiology has introduced the updated SCORE2 tool, and China relies on the China-PAR Calculator. Let's see how the Prevent Calculator works with a couple of examples.

Applying the risk calculator

Low-risk profile, 43-year-old female

[04:45]

First, meet a 43-year-old female. Her total cholesterol is 130 mg / dL, HDL is 60 mg / dL, and her systolic blood pressure is 120 mmHg. Her BMI is 30 and her estimated glomerular filtration rate, or eGFR, is 95. She doesn't have diabetes, doesn't smoke, hasn't been treated for high blood pressure, and isn't on cholesterol lowering medications. We can determine that her 10 year CVD risk is 0.7% and her lifetime CVD risk is 6%. Let's look at another example. 

High-risk profile, 55-year-old male

[05:27]

Now let's look at a 55-year-old male. His total cholesterol is 180, HDL is 20, systolic blood pressure is 118, his BMI is 20, and his eGFR is 110. He has diabetes, smokes cigarettes, and is being treated for hypertension. He's also on a statin. Using the same calculator, his 10 year CVD risk is 18.7% and his lifetime CVD risk is 49.5%. These examples highlight how additional risk factors can dramatically increase both 10 year and lifetime cardiovascular risk. 

Patients who require treatment regardless of risk

[06:10]

There are two special patient populations to consider, those with diabetes and those with severe hypercholesterolemia, defined as an LDL level greater than 190 mg / dL. These patients require treatment regardless of their calculated risk, but we'll dive into their management in another Medmastery lesson. 

Cardiovascular risk stratification: the four categories

[06:31]

Once screening is complete and the 10 year cardiovascular risk is calculated, patients fall into one of four categories. Low risk with less than 5%, borderline risk between 5 and 7.4%, intermediate risk from 7.5 to 19.9%, and high risk at 20% or more. 

Beyond the lipid panel: imaging for cardiovascular risk

[06:54]

Imaging tools such as coronary artery calcium, or CAC, scoring and CT angiography are increasingly used to assess risk more accurately and guide lipid management. We'll explore these imaging techniques in more detail in a later lesson.