Think Your Cholesterol Is Normal Apob Testing May Tell A Different Story

For decades, low-density lipoprotein (LDL) cholesterol, often called “bad cholesterol”, has been one of the primary markers used to assess a person’s risk of heart disease. However, a recent study published in JAMA suggests that another blood test, called apolipoprotein B (apoB), may better identify people who are truly at risk of heart attacks and strokes.

Researchers say apoB measures the number of harmful cholesterol-carrying particles in the bloodstream rather than just the amount of cholesterol they contain. This means that even people with normal LDL cholesterol could have a high number of atherogenic particles capable of damaging arteries, potentially placing them at a higher cardiovascular risk.

The study observed, “In primary prevention, would using an apolipoprotein B (apoB)) goal to guide intensification of lipid-lowering therapy (LLT) be more cost-effective than a low-density lipoprotein cholesterol (LDL-C) or non–high-density lipoprotein cholesterol (non–HDL-C) goal?”

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According to Dr K K Talwar, Chairman, PSRI Heart Institute, the study adds to growing evidence that apoB is a more accurate indicator of cardiovascular risk than LDL cholesterol alone.

“The results are important because they add to the growing body of evidence that ApoB is a better marker of cardiovascular risk than LDL cholesterol alone. LDL cholesterol measures the amount of cholesterol inside the LDL particles. ApoB measures the actual number of atherogenic lipoprotein particles that can enter the walls of arteries and cause plaque formation. Each of these harmful particles contains one molecule of apoB. This means that apoB directly measures how many particles there are that can cause atherosclerosis,” says Dr Talwar,

He adds that while the findings are promising, routine use of apoB testing will depend on future evidence. “If future studies confirm improved patient outcomes and cost effectiveness, apoB testing could become more prominent in clinical practice. apoB is already considered a useful risk assessment tool in several international guidelines, especially in selected high-risk individuals. But more real-world data on implementation and cost in different populations will be needed before it can be routinely used as a replacement for standard lipid testing.”

Dr Talwar says apoB testing is particularly useful for people whose cardiovascular risk may not be fully captured by a standard lipid profile.

“apoB testing is especially helpful in people whose risk for heart disease might be underestimated by traditional lipid tests. These are people who have diabetes, obesity, metabolic syndrome, high triglycerides, chronic kidney disease, a strong family history of premature heart disease, or who have had a cardiovascular event.”

He explains that in such individuals, LDL cholesterol can appear normal despite an elevated number of harmful lipoprotein particles.

“Testing for apoB can reveal this hidden risk and assist in more personalised treatment decisions.” However, he emphasises that apoB is not a replacement for the routine lipid profile.

“A standard lipid profile is still a good initial screening test for the general population at low cardiovascular risk. ApoB should be considered as an adjunct and not as a replacement for routine lipid testing, particularly when the clinical picture and cholesterol values are discordant, he says.”

“Yes, high apoB with normal LDL cholesterol can change your assessment of cardiovascular risk. The fact that the total cholesterol count is okay doesn’t mean there aren’t lots of cholesterol-carrying particles floating around in the bloodstream that could lead to plaque buildup in the arteries.”

That said, apoB is only one part of the overall risk assessment. “apoB alone should not be used to make treatment decisions. Doctors consider the patient’s overall cardiovascular risk profile, including age, blood pressure, diabetes, smoking status, family history and other risk-enhancing factors.”

If apoB is elevated alongside other risk factors, clinicians may recommend earlier lifestyle modifications or intensify lipid-lowering treatment. “In a person with high apoB and other risk factors, physicians may be more likely to suggest starting lifestyle interventions earlier or increasing lipid-lowering therapy, such as statins or other cholesterol-lowering drugs.”

Ultimately, he says, apoB allows for a more personalised approach. “ApoB enhances risk assessment and enables a more personalised treatment approach rather than substituting established risk calculators.”

Although apoB testing is becoming more accessible, it has not yet entered routine preventive screening in India. Dr Talwar says, “apoB testing is now available in many tertiary hospitals and private diagnostic laboratories across India, but it is not yet a routine part of lipid screening. The test is typically more expensive than a standard lipid profile, although prices have been consistently declining in urban settings.”