Apolipoprotein B — apoB
Cholesterol is difficult to understand. Not only does total cholesterol does not give a very accurate idea of a patient’s risk of cardiovascular disease, even knowing the fraction of HDL-Cholesterol (considered the “good” cholesterol) and LDL-Cholesterol (the “bad” cholesterol) does not always tell the true story. Generally those with higher HDL-C’s tend to have a lower risk of coronary disease (though increasing HDL-C using medications does not seem to lower risk) and those with higher LDL-C’s have higher risk (lowering LDL-C definitely lowers risk!), but there are patients with “low” LDL-C who still develop progressive coronary disease or suffer heart attacks and others with higher LDL-C who don’t— why is this?
Wrapped around each LDL particle is an apolipotrotein B (apoB) molecule; this same molecule is also found on VLDL and IDL particles and chylomicron remnants which can all contribute to coronary disease. The total number of apoB-wrapped particles in the blood is a much better indicator of coronary artery disease risk than the total concentration of LDL-Cholesterol in the blood (which is what current lipid profile tests estimate). The more apoB particles a patient has the greater the probability the cholesterol it contains will get trapped in an artery wall and contribute to a build-up of plaque. An LDL-C of 70 mg/dL can reflect a small number of apoB particles, each containing a relatively large amount of cholesterol, or a high number of apoB particles, each with only a small amount of cholesterol — the latter situation confers higher risk!
HDL-C does not have apoB and does not get trapped in the artery wall; it can actually remove deposited cholesterol from the artery and take it back to the liver. It is not understood why drugs that raise HDL-C levels fail to decrease cardiovascular risk, so for now the focus is on lowering apoB particle number.
ApoB correlates better with cardiovascular risk than LDL-C and lowering it has been shown to reduce events in a direct linear fashion. An apoB lower than 60 mg/dL is great. Under 30 mg/dL is probably even better!
Cost
Between $300 and $400 TTD