Total cholesterol, LDL (Low Density Lipoproteins) and HDL (High Density Lipoproteins) refers to the amount of cholesterol carried within different types of lipoproteins.
Having a high total cholesterol means that there are a lot of cholesterol in the blood. High LDL means that a lot of cholesterol in the blood is contained in LDL. High HDL means that a lot of it is contained in HDL.
Total cholesterol is actually a rather useless definition, because having high HDL contributes to a high total cholesterol. While having a lot of cholesterol in the bloodstream is not always a bad thing, unless this cholesterol is being carried around in the wrong lipoproteins, the LDL.
Having a lot of cholesterol within LDL is associated with heart disease. However, it is actually much more complicated than simply judging LDL as bad.
There are subtypes of LDL, mainly depending on the size and often classified as either small, dense LDL or large LDL. The size, as well as the amount of cholesterol carried are still meaningless without counting the LDL particle number.
In order to understand how the cholesterol, size and particles are interrelated is like filling a bucket with golf balls and tennis balls. The bucket is the total amount of cholesterol contained within LDL. The golf balls are small LDLs, while the tennis balls are large LDLs. The total number of balls is the LDL particle number.
We can fill the bucket with either tennis balls, or golf balls. The bucket will be just as full, but if we use golf balls, the number of balls in the bucket will be much greater.
Having more small particles will mean that there will be much higher number of particles, carrying the same amount of cholesterol. We can carry a certain amount of cholesterol in a high number of small LDLs, or we can carry the same amount in a low number of large LDLs.
People who have mostly small particles have up to a three times greater risk than people with mostly large particle. It’s not the small size that drives heart disease, but the fact that people with small particles tend to have a higher number of particles.