A standard cholesterol test is enough for many people, but it does not answer every question. Lipoprotein(a), or Lp(a), identifies a largely inherited source of risk. Apolipoprotein B, or ApoB, estimates the number of cholesterol-carrying particles that can enter artery walls.
That does not mean everyone needs an expensive “advanced lipid panel”. Some extra tests refine a real clinical decision. Others add detail without changing what should be done.
What does a standard cholesterol test already measure?
Cholesterol is a waxy substance that your body needs to make cell membranes, hormones and vitamin D. It does not dissolve in blood, so it travels in tiny packages made from fat and protein. These packages are called lipoproteins.
A cholesterol blood test measures the cholesterol carried inside different lipoproteins. A full lipid profile usually includes total cholesterol, HDL cholesterol and triglycerides. The laboratory then calculates LDL cholesterol and non-HDL cholesterol. Most people do not need to fast before it.
What is LDL cholesterol?
LDL carries cholesterol from the liver to the rest of the body. If too many LDL particles circulate for too long, some can become trapped in artery walls. This process contributes to coronary artery disease and can eventually cause a heart attack or stroke.
LDL is often called “bad cholesterol”. That is useful shorthand, but LDL is not a poison and everyone has some. The concern is having more LDL particles, or being exposed to them for longer, than is healthy for your overall level of risk.
What is HDL cholesterol?
HDL is involved in carrying cholesterol away from tissues and back towards the liver. Higher HDL levels are often associated with lower heart risk, which is why it is called “good cholesterol”. The biology is more complicated than the nickname suggests. A high HDL result does not cancel out high LDL, a high ApoB or a high Lp(a).
What is non-HDL cholesterol?
Non-HDL cholesterol is your total cholesterol minus HDL. It includes cholesterol carried in LDL and in the other particles that can contribute to fatty deposits in arteries. You can think of it as the overall harmful cholesterol carried in the blood.
It is not an extra laboratory test. It is calculated from the ordinary lipid profile, works well without fasting and is used in UK guidance to judge response to treatment. For many people it already provides much of the information that an advanced panel is trying to uncover.
What are triglycerides?
Triglycerides are a different type of fat. Your body uses them to store and transport energy. Raised levels can occur with diabetes, excess alcohol, excess weight, some medicines or an inherited condition. They also affect how we interpret LDL and non-HDL cholesterol.
Lp(a): the inherited risk that a routine panel can miss
Lp(a) is an LDL-like particle with an extra protein attached. Its level is determined mainly by your genes, so diet, exercise and weight loss usually make little difference to the number itself.
A high Lp(a) is associated with a greater lifetime risk of heart attack, stroke and aortic valve disease, particularly narrowing caused by calcium build-up. Risk rises gradually rather than changing suddenly at one cut-off.
European guidance regards a result above about 105 nmol/L, or 50 mg/dL, as a factor that can increase cardiovascular risk. Other statements use 125 nmol/L as the start of the high range. The units should not be converted with a fixed formula because Lp(a) particles vary in size.
A raised result does not prove that artery disease is present or mean that a UK 10-year risk score should simply be multiplied. It prompts a closer look at blood pressure, smoking, diabetes, kidney function, family history and the rest of the lipid profile.
Who should have Lp(a) measured?
International recommendations increasingly support one measurement in adult life. It is particularly helpful with:
- a heart attack or stroke at an unusually young age, or a strong family history
- suspected familial hypercholesterolaemia, an inherited cause of very high cholesterol
- heart or circulation disease despite apparently reasonable LDL cholesterol
- uncertainty about how actively to treat an otherwise borderline level of risk
- a first-degree relative with a markedly raised Lp(a)
Lp(a) is not included in every NHS cholesterol panel. Because it is usually stable, repeat testing is rarely useful unless there is doubt about the result or a temporary condition may have affected it.
What can be done if Lp(a) is high?
There is currently no Lp(a)-specific medicine with proven benefit against heart attacks and strokes available for routine UK use. Several treatments are being studied.
For now, the practical response is to lower the risks that can be changed. This may mean lowering LDL or non-HDL cholesterol, controlling blood pressure, avoiding smoking and managing diabetes. A high Lp(a) alone is not a reason to start aspirin or arrange a heart scan. Those decisions need a separate medical reason.
Because Lp(a) runs in families, a one-off test for close relatives can be worth discussing when a result is clearly high.
ApoB: counting particles rather than their cholesterol cargo
Each particle that can contribute to fatty deposits in arteries carries one ApoB molecule. ApoB therefore estimates how many of these particles are circulating.
Imagine two people carrying the same weight of shopping. One has a few full bags; the other has many lighter bags. LDL cholesterol measures the contents. ApoB is closer to counting the bags. Two people can therefore have the same LDL cholesterol but different particle numbers. When the results disagree, risk tends to follow ApoB more closely.
When does ApoB add useful information?
ApoB is most helpful when LDL cholesterol may look reassuring despite a larger number of smaller particles. This is more common with:
- raised triglycerides
- type 2 diabetes, excess weight, or a combination of raised blood sugar, blood pressure and triglycerides
- LDL cholesterol that is already low after treatment, but concern remains about particle number
- heart or circulation disease that seems out of proportion to the standard result
ApoB changes little after eating, so fasting is not usually required. It is a useful test, but LDL and non-HDL cholesterol often provide the same answer. When the routine results and the wider risk assessment agree, ApoB may not change the plan.
Non-HDL cholesterol: the useful result people often overlook
Non-HDL measures the cholesterol inside all the potentially harmful particles, while ApoB estimates their number. The two usually agree, so non-HDL often provides enough information without another test or extra cost.
What about the other tests on advanced lipid panels?
Several other results appear on private panels, but they are less likely to change treatment:
- ApoA1 and the ApoB:ApoA1 ratio: ApoA1 is the main protein in HDL. The ratio can predict risk, but rarely adds much beyond ApoB or non-HDL cholesterol. A favourable ratio does not cancel a high Lp(a).
- Remnant cholesterol: This is cholesterol carried in particles left after the body processes triglyceride-rich particles. It is linked with heart attack and stroke risk, but can be estimated from the routine profile. Triglycerides, non-HDL and sometimes ApoB are usually more practical.
- LDL particle number, size and small dense LDL: These tests are less standardised. ApoB usually answers the useful particle-number question more simply. A report describing “pattern B” often reflects changes already visible in triglycerides, HDL, weight or blood sugar.
- Oxidised LDL: This is involved in fatty deposits inside arteries, but commercial measurements are not standardised well enough to guide routine treatment.
- High-sensitivity CRP: This measures inflammation, not cholesterol. It can refine risk in selected cases but rises for many other reasons, so a single result can mislead.
- Genetic testing: This can help when an inherited cause of very high cholesterol is suspected. It is not a general screening test for everyone with mildly raised cholesterol.
A sensible testing approach
For most adults, I would start with a standard lipid profile and cardiovascular risk assessment, then ask two questions:
- Is there an inherited risk that the routine panel may miss? A one-off Lp(a) test can answer part of this.
- Could the number of harmful particles be higher than the LDL cholesterol suggests? ApoB is useful when there are raised triglycerides, diabetes, related weight or blood-sugar problems, or results that do not agree with one another.
The purpose of testing is not to produce the longest possible list of biomarkers. It is to resolve uncertainty and change a decision. If a result will not alter advice, treatment or family screening, its value is limited.
Dr Mark Cassar can assess cholesterol and inherited cardiovascular risk in clinic, review previous results and family history, and arrange further testing where appropriate. If you would like a personalised review, the appointments page has details on arranging a consultation. You can also read more about high cholesterol and the questions patients commonly ask about statins.
Questions patients often ask
Should everyone have an Lp(a) test?
A once-in-adulthood measurement is increasingly recommended internationally. It is particularly useful after a heart attack or stroke at an unusually young age, with a strong family history, with an inherited cause of very high cholesterol, or when the standard tests do not explain the apparent risk. It is not included in every routine UK panel.
Do I need both ApoB and Lp(a)?
They answer different questions. ApoB estimates the number of potentially harmful particles. Lp(a) identifies one inherited particle with additional risk. Neither replaces the standard profile or an overall risk assessment.
Can diet lower Lp(a)?
Lifestyle changes usually have little effect on the Lp(a) level itself because it is mainly genetic. They can still reduce overall risk by improving blood pressure, diabetes, smoking status, fitness and other lipid measurements.
Is ApoB better than LDL cholesterol?
ApoB can be more informative when the two results disagree, particularly with raised triglycerides, diabetes or related weight and blood-sugar problems. For many people they agree closely, and the standard LDL and non-HDL results are sufficient.
Do I need to fast for these tests?
Usually not. A standard lipid profile, ApoB and Lp(a) can generally be measured without fasting. A fasting repeat may be requested if triglycerides are substantially raised or the laboratory cannot calculate LDL cholesterol reliably.
If my Lp(a) is high, do I need a heart scan?
Not automatically. Lp(a) modifies risk but does not prove that disease is present. Imaging is most useful when symptoms, examination findings or a specific treatment decision provide a clear clinical reason for it.
