ApoA1

What is ApoA1?

Cholesterol does not dissolve in blood and therefore travels in particles with a protein on the outside. On the LDL particles and the other particles that can deposit cholesterol in the vessel wall that is ApoB; on the HDL particles, which bring cholesterol back out of the vessel wall and take it to the liver, that is ApoA1. That protein does more than hold the particles together: it switches on the enzyme that locks cholesterol inside the particle, and it is the key with which the particle collects cholesterol from the vessel wall. That difference decides what you measure. HDL cholesterol weighs how much cholesterol the HDL particles carry; ApoA1 counts the particles themselves. Two people with the same HDL cholesterol can have a different number of particles: one with few heavily loaded particles, the other with many light ones. Many particles with little cholesterol in them give a high ApoA1 with a modest HDL, and that means many collectors are circulating that still have room. Your report prints ApoA1 in g/L; unlike the cholesterol values you do not need to watch mmol/L against mg/dL here. Normal is roughly 1.04 to 1.78 g/L in men and 1.08 to 1.99 g/L in women, where the labs overlap, and women naturally sit slightly higher through oestrogen. Higher is favourable.

Why is ApoA1 relevant?

ApoA1 is the counterpart of ApoB: the one protein sits on the particles that can deposit cholesterol in the vessel wall, the other on the particles that take it back out. Anyone who measures both counts the supply and removal of cholesterol in particles instead of in weight, and the ratio between those two predicted the risk of a heart attack more strongly than LDL cholesterol in large studies. The second reason is that ApoA1 shows what lifestyle does to the collecting side. Exercise, losing weight and stopping smoking lift the number of HDL particles, and ApoA1 moves along. Belly fat, little exercise and insulin resistance lower it, as does smoking. A low ApoA1 with high triglycerides is the fat pattern of insulin resistance, and that is the pattern lifestyle changes most. The honest limitation is that the Dutch risk estimate does not work with it. It works with LDL and non-HDL, and does not recommend measuring apolipoproteins routinely. A high HDL, and so a high ApoA1, also protects less than was long thought: lifting HDL with medicines turned out not to prevent heart attacks. So read ApoA1 beside your HDL and ApoB, not instead of them, and let the decision on a statin fall on LDL and non-HDL.

ApoA1 high or low: what it means

A low ApoA1 means there are fewer particles bringing cholesterol back out of the vessel wall. Usually it is the first and rarely the last: excess weight, little movement and insulin resistance, the pattern that lowers HDL and pulls the carrying protein down with it; smoking, which lowers the number of HDL particles; and an underactive thyroid, which changes the whole fat balance. A low value therefore usually moves along with a low HDL, and the approach is the same. A high ApoA1 is favourable and belongs with a high HDL: more particles means more carrying protein, so the two usually move together. Regular exercise lifts it by the same route as HDL cholesterol, and women naturally sit higher through oestrogen; oestrogen in tablet form lifts it further still. If ApoA1 and HDL diverge, that says something about the loading of the particles: many particles with little cholesterol in them give a high ApoA1 with a modest HDL. What you do about it: exercise, also vigorously and regularly, because that is the strongest stimulus for more HDL particles; lose weight if you carry belly fat, because that lowers the insulin resistance that reduces ApoA1; stop smoking, and replace saturated fat and fast sugars with unsaturated fat from olive oil, nuts and oily fish and with fibre. Count on three months before the change is visible. Medicines that specifically lift HDL no longer exist as a route, because they prevented no heart attacks. ApoA1 belongs beside your HDL cholesterol, because the two describe the same particles from two sides, beside ApoB, because the ratio between those two is what this test is usually requested for, and beside the triglycerides, which show whether the pattern of insulin resistance is at play. Compare only with the band on your own report, because the two labs that publish one set it differently.

How does an ApoA1 blood test work?

Referral

Not needed. The test can be requested on its own, though it is not in the ordinary lipid profile; request ApoB with it, because the ratio between those two is what this test is usually meant for.

Fasting

Not needed. Unlike the triglycerides, the timing of meals hardly counts here.

When

On an ordinary day, not during or just after an illness, because an infection lowers the lipid values temporarily. Three months after a change in exercise, weight or smoking to see the effect.

The draw

One tube of blood from a vein in your arm. ApoA1, ApoB and HDL cholesterol come from the same tube, and that is how it should be, because you compare them with each other.

Repeating

Once a year, or three months after a change in lifestyle. Compare only with the band of the lab that processed your blood, because the two bands that exist diverge.

Which test

ApoA1 is in the Heart health test (€69).

Where to draw

You can draw at 250+ locations near you, no referral needed. See the locations

Educational information only, not medical advice. Consult a healthcare professional for clinical decisions.