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 Test picks up that particle-number detail, which an LDL cholesterol result does not report on its own.
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.
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)?
The Australian Guideline for Assessing and Managing Cardiovascular Disease Risk (Heart Foundation and the Australian Chronic Disease Prevention Alliance, 2023) is more conservative here than some international commentary. It states that routine ApoB and Lp(a) testing is not currently recommended for calculating cardiovascular risk scores in people with no known heart disease, and that there is no case for testing Lp(a) across the general population. The guideline reserves Lp(a) testing for narrower situations, including people:
- Already living with cardiovascular disease (secondary prevention)
- With confirmed familial hypercholesterolaemia
- With recurrent or premature cardiovascular disease, including a strong family history of it
- Whose LDL cholesterol has not come down as expected despite treatment
Outside these settings, testing ApoB or Lp(a) is more a matter of personal interest than a guideline-backed recommendation. 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 Australia
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 Test | ApoB, ApoA1 and the ApoB/ApoA1 ratio | $69 | | Advanced Lipid Test | A full lipid panel plus ApoB, Lp(a), LDL particle size and number, and a range of additional lipoprotein subfraction markers | $295 | | Cardiovascular Health Test | A broader panel combining standard cholesterol, ApoB, Lp(a), inflammation (hsCRP), homocysteine and blood glucose markers | $199 |
Ordering is straightforward: order online, collect a sample at a partner collection centre, and view results through the online dashboard once a NATA-accredited lab has processed them.
For a wider view of cardiovascular health, including inflammation and genetic risk markers, the i-screen Improve 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 Australia?
No referral is needed. Both markers can be ordered online and tested through a NATA-accredited lab after a sample is collected at a partner collection centre.
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.
