Cholesterol: How to interpret your lipid panel

You've received your blood test results. On the sheet, there are numbers, abbreviations, and reference values. LDL, HDL, triglycerides, total cholesterol. Some are in red, others seem within limits. But what all of this concretely means for your health is rarely explained in detail when you receive the document.

The lipid panel is one of the most useful preventive screenings available. However, you need to know how to read it.

What a lipid panel measures

The standard lipid panel includes four main measurements. Total cholesterol gives an overview of the amount of cholesterol circulating in the blood, but it doesn't tell us much on its own. It's the breakdown into different fractions that matters.

LDL, or low-density lipoprotein, is often referred to as "bad" cholesterol. In excess, it deposits on artery walls, contributing to the formation of atherosclerotic plaques that gradually narrow blood vessels and increase the risk of heart attack and stroke. It is the most monitored value in cardiovascular risk assessment.

HDL, or high-density lipoprotein, is good cholesterol. It retrieves excess cholesterol from tissues and arteries to bring it back to the liver, where it is eliminated. High HDL is protective. Low HDL, on the other hand, is a cardiovascular risk factor, even if LDL levels are normal.

Triglycerides are fats stored in the blood after meals. High levels are often associated with a diet rich in refined sugars and alcohol, a sedentary lifestyle, and being overweight. In combination with low HDL and high LDL, high triglycerides form what is known as mixed dyslipidemia, a particularly unfavorable cardiovascular profile.

Reference thresholds in Canada

Target values vary depending on the individual's overall risk profile. For an adult at average risk, Canadian recommendations suggest LDL below 3.5 mmol/L, HDL above 1.0 mmol/L in men and 1.3 mmol/L in women, and triglycerides under 1.7 mmol/L (Canadian Cardiovascular Society, 2021). For individuals with a history of cardiovascular disease, diabetes, or kidney failure, targets are stricter, and the desired LDL can be as low as below 2.0 mmol/L, or even below 1.8 mmol/L in very high-risk cases.

These numbers are targets, not absolute thresholds. A result slightly above the norm in a young person with no risk factors does not mean the same thing as the same result in a 60-year-old with hypertension and diabetes. It is the entire clinical picture that the doctor or NP evaluates, not an isolated value.

What causes cholesterol to rise

Diet plays a role, but not as central a role as is often believed. Genetics is actually the most determining factor in cholesterol regulation for many people. Familial hypercholesterolemia, a hereditary condition affecting about 1 in 250 people in Canada, leads to very high LDL levels from a young age, regardless of dietary habits.

When it comes to modifiable habits, saturated fats and trans fats, found in ultra-processed products, fatty meats, and certain tropical oils, raise LDL. Sedentary behavior lowers HDL. Excess refined sugars and alcohol increase triglycerides. Smoking lowers HDL and speeds up LDL oxidation, making it more damaging to artery walls.

Certain medical conditions such as hypothyroidism, polycystic ovary syndrome, and certain kidney diseases can also significantly alter the lipid profile. This is one of the reasons why a lipid panel is always interpreted in the context of a complete health assessment.

Total cholesterol to HDL ratio

Beyond individual values, the ratio between total cholesterol and HDL is often used as a synthetic indicator of cardiovascular risk. A ratio below 4.0 is generally considered favorable. The lower this ratio, the better the profile. This simple calculation incorporates both the protection offered by HDL and the risk associated with high LDL, making it a more nuanced indicator than total cholesterol alone.

Frequently Asked Questions About Lipid Panel

Can you have high cholesterol without eating fatty foods?
Yes. Genetics are often more decisive than diet. Some people maintain high LDL even with a very balanced diet, due to naturally higher hepatic cholesterol production.

Do eggs really raise cholesterol?
The question is more nuanced than we thought. Recent studies indicate that eggs consumed in reasonable quantities have no significant effect on LDL for the majority of people. It is mainly saturated fats and trans fats that have a greater influence on lipid profiles.

Should you start taking a statin as soon as your LDL exceeds the norm?
Not necessarily. The decision to prescribe a statin depends on the overall 10-year cardiovascular risk, not just the LDL level. This is an assessment that the doctor or NP makes, taking into account age, sex, blood pressure, smoking, and family history.

How often should you get a lipid panel?
For an adult without risk factors, every five years starting at age 40 is generally sufficient. For individuals with cardiovascular risk factors, annual or bi-annual monitoring may be recommended depending on their profile.

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