Cholesterol Results Explained: LDL, HDL, Triglycerides and Non HDL

Your cholesterol results are back, and you see five or six numbers with words like LDL, HDL, and non-HDL. One may be flagged. You may wonder if you need a statin. This guide explains what each number means and how clinicians in Canada and the US use them.

What a lipid panel measures

A cholesterol test is also called a lipid panel or lipid profile. It measures fats in your blood that affect your risk of heart attack and stroke [1].

• Total cholesterol: all the cholesterol in your blood.
• LDL cholesterol (low-density lipoprotein): often called "bad" cholesterol. It builds up in artery walls.
• HDL cholesterol (high-density lipoprotein): often called "good" cholesterol. It helps carry cholesterol away from arteries.
• Triglycerides: another type of fat. Levels rise after meals, with alcohol, and with diabetes or extra weight.
• Non-HDL cholesterol: total cholesterol minus HDL. It counts all the particles that can clog arteries, not just LDL.

Some reports also include apolipoprotein B (apoB), which counts the number of harmful particles. Lipoprotein(a), or Lp(a), is a separate test.

Units

Canadian labs report in millimoles per litre (mmol/L). US labs report in milligrams per decilitre (mg/dL). For LDL, HDL, and total cholesterol, multiply mmol/L by about 38.7 to get mg/dL. So 2.6 mmol/L is about 100 mg/dL.

Do you need to fast?

For most people, no. Both Canadian and US guidance accept non-fasting tests [2][3]. Triglycerides are a little higher after eating. If they are very high, your clinician may repeat the test after fasting.

What your doctor looks at

The most important point: treatment decisions depend on your overall risk of heart disease, not just on your LDL. Two people with the same LDL can have very different risks.

Step 1: Are you already at high risk?

Some people are treated mainly because of their condition [2][3].

• People who have had a heart attack, stroke, or blocked arteries.
• People with very high LDL, about 5.0 mmol/L (190 mg/dL) or more. This can signal familial hypercholesterolemia, an inherited condition. Family members may need testing.
• Many adults with diabetes, especially from age 40.
• Many people with chronic kidney disease.

Step 2: Estimate your risk

For everyone else, clinicians use a risk calculator. It combines age, sex, blood pressure, smoking, diabetes, and cholesterol.

• In Canada, the Canadian Cardiovascular Society (CCS) 2021 guideline uses the Framingham Risk Score or the Cardiovascular Life Expectancy Model. A 10-year risk of 20 percent or more generally points to a statin. A risk of 10 to 19.9 percent points to a statin when LDL is 3.5 mmol/L or higher, or non-HDL is 4.2 mmol/L or higher, or other risk factors are present [2].
• In the US, the 2026 American College of Cardiology and American Heart Association (ACC/AHA) multisociety guideline replaced the older calculator with the PREVENT equations. It estimates 10-year risk, and 30-year risk for adults aged 30 to 59 [3][4].

Clinicians then add "risk enhancers," such as a strong family history of early heart disease, high Lp(a), or early menopause. A coronary artery calcium scan can help when the decision is unclear.

Step 3: Set a goal

Both guidelines use LDL, non-HDL, or apoB to guide treatment once it starts.

• The CCS guideline suggests adding treatment for people with heart disease whose LDL stays at 1.8 mmol/L or higher, or non-HDL at 2.4 mmol/L or higher, on a statin [2].
• The 2026 US guideline brought back explicit goals for LDL, non-HDL, and apoB based on risk group. Goals are lowest for people who already have heart disease [3][4].

Lipoprotein(a)

Lp(a) is mostly set by your genes and changes little over life. The CCS guideline recommends measuring it once in adult life [2]. The 2026 US guideline also recommends checking Lp(a) at least once [4]. A high Lp(a) raises your risk and can tip the balance toward treatment.

Triglycerides

A fasting triglyceride level below about 1.7 mmol/L (150 mg/dL) is generally considered normal [5]. Very high levels, about 10 mmol/L (885 mg/dL) or more, raise the risk of pancreatitis (inflammation of the pancreas). This needs prompt attention.

HDL

Low HDL, below about 1.0 mmol/L in men or 1.3 mmol/L in women, is a risk factor. But raising HDL with medicine has not been shown to prevent heart attacks, so HDL is not a treatment target.

Where Canada and the US differ

• Risk tools: Canada uses Framingham-based tools. The US now uses PREVENT.
• When to start testing: The 2026 US guideline supports screening from childhood and every 5 years in adults [4]. The CCS suggests screening men and women from age 40, or earlier with risk factors [2].
• Both now put more weight on non-HDL, apoB, and Lp(a) than older guidance did.

Questions to ask your clinician

• What is my estimated 10-year risk of heart attack or stroke?
• Which calculator did you use, and what went into it?
• Is my LDL high enough to suggest an inherited condition?
• Should I have my Lp(a) or apoB checked?
• What would treatment lower my risk by, in absolute numbers?
• What lifestyle changes would make the most difference for me?
• When should I repeat this test?

When to get care quickly

Call 911 if you have chest pain or pressure, pain spreading to your arm, jaw, or back, sudden shortness of breath, or signs of stroke such as face drooping, arm weakness, or trouble speaking. Severe upper stomach pain that spreads to your back, with very high triglycerides, also needs emergency care.

Bottom line

Your cholesterol numbers matter most as part of your overall heart risk. Clinicians look at LDL, non-HDL, apoB, and Lp(a), then combine them with age, blood pressure, smoking, and diabetes. Canada and the US use different risk calculators, but both aim treatment at people most likely to benefit.

Primary AI can show you the guideline and study sources behind this topic in plain language, so you can bring better questions to your appointment.