A standard cholesterol test reports total cholesterol, LDL, HDL and triglycerides. It doesn't report ApoB or Lp(a), two markers that sit outside that panel: the number of cholesterol-carrying particles in the blood (ApoB), and a largely inherited lipoprotein a routine lipid panel does not capture at all (Lp(a)). Neither marker replaces a standard cholesterol test. Both add information a standard panel does not report on its own.
This guide covers what each marker measures, what they add to a standard cholesterol result, who might consider testing them, and how to test both without a GP referral.
What is ApoB, and what does it measure?
Apolipoprotein B (ApoB) is a protein found on the surface of LDL, VLDL and IDL particles, the lipoproteins that carry cholesterol through the bloodstream. Each of these particles carries exactly one ApoB molecule, so an ApoB result is effectively a count of how many cholesterol-carrying particles are circulating, rather than a measure of how much cholesterol those particles contain.
That distinction matters because cholesterol isn't always distributed the same way between two people. Someone can have an unremarkable LDL cholesterol result while carrying that cholesterol in many small, numerous particles rather than fewer, larger ones. An Apolipoprotein (ApoB) Check picks up that particle-number detail, which an LDL cholesterol result does not report on its own. This is also why the 2026 US multisociety dyslipidaemia guideline highlights ApoB testing as useful for spotting residual lipoprotein risk in people who have already reached their LDL-C or non-HDL-C targets.[3]
What is Lp(a), and how is it different from other cholesterol markers?
Lipoprotein(a), or Lp(a), is an LDL-like particle bound to a distinct protein called apolipoprotein(a). Like LDL, VLDL and IDL particles, each Lp(a) particle also carries one ApoB molecule, which is part of why the two markers are often discussed together, even though Lp(a) is driven mostly by genetics rather than by particle number. It is not part of a standard lipid panel, and its level is largely determined by the LPA gene rather than diet, exercise or lifestyle. Levels are generally set from an early age and tend to stay fairly stable across a person's life (aside from some secondary influences, such as kidney, liver or thyroid disease, pregnancy or menopause), which is one reason a single measurement is generally considered enough once a baseline result is known, rather than repeat testing.
A raised Lp(a) result is linked to cardiovascular risk and can sit alongside otherwise unremarkable cholesterol results. Lp(a) correlates only weakly with LDL cholesterol, so a normal LDL-C result does not rule out a markedly raised Lp(a), which is one of the reasons it is not captured by a standard panel.
HEART UK's consensus statement sets out four Lp(a) risk bands: 32-90 nmol/L (minor risk), 90-200 nmol/L (moderate risk), 200-400 nmol/L (high risk), and above 400 nmol/L (very high risk).[1] Other guideline bodies use different cut-offs for the same marker, so these bands are best read against whichever reference range your own test report cites, rather than compared directly across sources.
What do ApoB and Lp(a) add to a standard cholesterol test?
A standard lipid panel and these two markers report on different things. The table below sets out what each covers.
| Marker | What it reports | Included in a standard cholesterol test? | | --- | --- | --- | | Total cholesterol, LDL, HDL, triglycerides | Cholesterol and triglyceride levels | Yes | | ApoB | Number of cholesterol-carrying particles | No | | Lp(a) | A largely inherited lipoprotein | No | | LDL particle size and number | Detail on particle size and count | No |
For some people, cholesterol results look unremarkable on a standard panel while ApoB or Lp(a) sits outside the typical range. In these cases, the two markers add information a standard test does not report, rather than showing the standard test was wrong. Results are best discussed with a GP or other treating practitioner.
Who might consider testing ApoB and Lp(a)?
HEART UK's consensus statement on Lp(a) sets out who Lp(a) testing is most relevant for, rather than recommending it across the general population. It points to:
- People with a personal history of cardiovascular disease before age 60, or a family history of premature cardiovascular disease
- First-degree relatives of someone already known to have a raised Lp(a) result
- People with familial hypercholesterolaemia or another inherited lipid disorder
- People with calcific aortic valve disease, or a relevant family history
- People with a borderline increased (but under 15%) 10-year cardiovascular risk score
That risk-targeted approach is still where UK-specific guidance sits, but international guidance has been shifting toward broader testing. The European Society of Cardiology and European Atherosclerosis Society's 2025 focused update states that Lp(a) measurement "should be considered at least once in every adult's lifetime," rather than only in specific risk groups.[2] A 2026 US multisociety guideline goes further, recommending Lp(a) testing for all adults at least once regardless of risk category.[3] HEART UK's UK-specific consensus, still the primary reference point for testing decisions in the UK, hasn't yet moved to this broader once-in-a-lifetime position, so the risk-factor list above remains the practical starting point for anyone testing in the UK.
Within NHS care, Lp(a) isn't routinely measured in general practice, and testing typically means a referral to a specialist lipid clinic. Outside these settings, testing ApoB or Lp(a) privately is more a matter of personal interest than a guideline-backed recommendation for everyone. Either way, these markers are relevant to cardiovascular risk assessment generally, rather than to any single diagnosis, and whether testing is worthwhile for a given person is best worked through with a GP or other treating practitioner.
How to test ApoB and Lp(a) in the UK
Testing for ApoB and Lp(a) doesn't require a GP referral. i-screen offers a few ways to test these markers, depending on how much additional detail is wanted alongside them.
| Test | What it covers | Price | | --- | --- | --- | | Apolipoprotein (ApoB) Check | ApoB, ApoA1 and the ApoB/ApoA1 ratio | £140 | | Lipoprotein Particle Check | A full lipid panel plus Lp(a), LDL particle size and number, and a range of additional lipoprotein subfraction markers | £192 | | Cardiovascular Check | A broader panel combining standard cholesterol, the ApoB/ApoA1 ratio, Lp(a), inflammation (hsCRP), homocysteine and blood glucose markers | £250 |
Ordering is straightforward: order online, then book a venous blood draw through a phlebotomy service (details are provided with your kit), and view results through the online dashboard once your sample has been processed.
There isn't currently a single mandated UK standard specifying exactly when Lp(a) or ApoB should be added to a lipid panel, or how results should be reported. A 2025 joint statement from HEART UK and the Association for Laboratory Medicine was written specifically to close that gap, noting the previous absence of national guidance on lipid testing and reporting for UK laboratories and clinicians, and working toward more consistent practice across UK labs.[4] Until that standardisation is complete, the panels above reflect one reasonable way of grouping these markers, rather than a single official specification.
For a wider view of cardiovascular health, including inflammation and genetic risk markers, the i-screen Heart & Cardiovascular Health hub groups the related tests together in one place.
Making sense of the results
ApoB and Lp(a) results are best read alongside the rest of a standard cholesterol panel and other risk factors such as blood pressure, smoking history, diabetes and family history, not in isolation. A GP or other treating practitioner is the right person to interpret what a specific result means for an individual and whether any follow-up is needed.
Anyone already managing high cholesterol might also find it useful to start with i-screen's guide on what to do about high cholesterol, which covers everyday changes that influence standard cholesterol markers.
FAQs
Does an ApoB test replace a standard cholesterol test?
No. ApoB adds information a standard lipid panel does not report, the number of cholesterol-carrying particles, rather than replacing it. Both are best read together, alongside the rest of a person's cardiovascular risk picture.
Can Lp(a) be high even when cholesterol results are normal?
Yes. Lp(a) is a separate, largely inherited lipoprotein that a standard lipid panel does not measure, so it can sit outside the typical range even when total cholesterol, LDL and HDL results look unremarkable.
Do I need a GP referral to test ApoB or Lp(a) in the UK?
Not to order privately. Within NHS care, Lp(a) testing usually means a referral to a specialist lipid clinic, but ApoB and Lp(a) can both be ordered online through i-screen and tested via a venous blood draw without a referral.
This article is for general information and does not replace advice from a qualified health practitioner. Always discuss test results with a GP or another treating practitioner. i-screen provides wellness and educational services only. Our services do not diagnose, treat, cure, or prevent any disease or medical condition.
