ApoB and cholesterol testing, and what the results tell you

What the tests measure

A full lipid profile measures total cholesterol and HDL cholesterol alongside triglycerides, the main fat carried in the blood. From these it calculates non-HDL cholesterol and LDL cholesterol, and it does not need a fasting sample [1].

ApoB is a protein carried by every particle that can carry cholesterol into the artery wall, including LDL and Lp(a), carries one molecule of it, so an ApoB result is a count of those particles [2]. Cholesterol enters the artery wall only inside these particles, and the amount each one carries varies, which is why the count and the cholesterol figure can tell different stories [2].

Why it is done and who it is for

A cholesterol test is how a doctor estimates your risk of heart attack and stroke. In the UK, NICE asks doctors to use the QRISK3 tool for adults aged 25 to 84 without heart disease, and to offer a statin when the 10-year risk is 10% or more [1].

ApoB is most useful when the usual numbers may mislead. The 2021 Canadian guideline prefers ApoB or non-HDL cholesterol to LDL cholesterol for anyone with triglycerides above 1.5 mmol/L [3]. In a study of 389,529 people not taking cholesterol treatment, ApoB was the only measure still linked to heart attack when the measures were compared together [4].

Testing matters more if your total cholesterol is above 7.5 mmol/l, or you or a parent, brother, sister or child had heart disease before 60, because NICE asks doctors to consider familial hypercholesterolaemia in that case [5].

Who it is not for

A planned blood test is the wrong first step for chest pain, sudden breathlessness, fainting or signs of a stroke. In the UK call 999, and elsewhere call the local emergency number.

If you already have heart disease or are under a lipid clinic, follow the targets your specialist has set, and ask them before adding tests that will not change your plan. ApoB is an addition to the full lipid profile, which remains the basis of risk assessment in UK guidance [1].

Benefits and limitations

The benefit is a clear measure you can act on with a doctor, and for many people a reassuring one. ApoB can show a raised particle count that a normal LDL figure hides, and Lp(a), tested at the same draw, is worth measuring at least once in adult life [6].

A single result is one moment, and it is not a diagnosis. NICE asks doctors to judge an inherited lipid disorder from the whole clinical picture and the family history rather than from strict cut-offs alone [1]. A normal result can also give false reassurance if smoking or blood pressure is the larger risk.

Risks

The blood draw itself is low risk, with a small chance of a bruise or feeling faint. The larger effect is what follows a result. A very high value leads to more tests, and NICE advises specialist assessment for a total cholesterol above 9.0 mmol per litre or a non-HDL cholesterol above 7.5 mmol per litre [1]. The doctor explains any such step before you decide.

How you prepare

You can eat and drink as usual for a lipid test [1]. If the same draw includes fasting glucose or insulin, you will be told to fast beforehand. A very high triglyceride result between 10 and 20 mmol per litre is repeated as a fasting test [1].

• A list of your medicines and supplements, including any statin
• Previous cholesterol results, with their dates
• Any heart disease or high cholesterol in your parents, brothers or sisters, and the age it began
• Whether you smoke, and your usual blood pressure if you know it

What to expect on the day

A clinician takes one sample from a vein in your arm, which takes a few minutes. You can return to work straight afterwards.

Results and what happens next

A doctor reads your results with you, sets them against your overall risk and agrees what to do. Often that means changes to how you eat and move, and sometimes a statin.

If you start treatment, NICE aims for a fall of more than 40% in non-HDL cholesterol and repeats the full profile 2 to 3 months after starting or changing treatment [1]. If your results suggest an inherited condition, a specialist can arrange DNA testing and offer testing to your relatives [5].

Questions to ask your doctor

These questions help you leave with a plan rather than a number.

• What is my 10-year risk, and what drives it most?
• Do my ApoB and LDL results agree, and if not, which should we follow?
• What would change your advice about a statin?
• When should I repeat the test, and should my family be tested?

How The Wellness can help

The Core Wellness blood test includes a full lipid panel with HbA1c, TSH, ferritin and a marker of inflammation, and Longevity+ adds ApoB, Lp(a), homocysteine and fasting insulin with a written plan. Every result is explained by a GMC registered doctor, and samples go to accredited laboratories.

Our London clinics are on Baker Street in Marylebone and Eccleston Street in Belgravia, open every day from early morning to evening. Outside London, appointments are arranged with partners in 12 city pages.