Many people run a cholesterol profile, most people after 50 in the Western world, I would say. And the aim of this test is coming out of it cleared, i.e. having low values of cholesterol or, at least, high HDL, the good guy, and low LDL, the bad guy. If you get a high HDL/LDL you come out of the doc's office with a smile.
But, is it so simple? Is HDL the real good cholesterol and having high values of it a good enough result to sleep peacefully at night not worrying of an imminent heart attack?
Well, first of all, HDL is not cholesterol but a complex of fats and proteins in the form of a sphere (lipoprotein) that transports cholesterol. The HDL type of lipoprotein is supposed to be the good one (compared to the LDL or VLDL type) because it helps clearing cholesterol from the arteries and from blood by gulping it and moving it into the liver.
However, a very recent research found out that some people with very high HDL are at high risk of atherosclerosis and accumulation of cholesterol on the arterial walls, thus at high risk of cardiovascular disease. The reason is because it is not sufficient to have high HDL (thus high chance to move cholesterol into the liver), but one needs to have also a good transport mechanism in place. And this is not always the case: some people have a genetic propensity to be weak in such transport: they lack a protein that makes the deposit into the liver happen smoothly.
Doctors prescribe medicines that help increase HDL in order to lower the risk of cardiovascular disease. However, sometimes such a measure is not going to work. In people where there is a deficient transport towards the liver, such drugs do not help lowering the risk of cardiovascular disease. These individuals show high HDL (so theoretically clustered into the group of people at low risk of cardiovascular disease) but have a genetic profile in which the gene designing the protein that makes the deposit in the liver happen is lacking. Such people have a very high level of plaque.
So having a profile with high HDL is not always a good sign. It might be high because the system in place to clear it out of the arteries is malfunctioning. Would we then need to run a genetic test to see if we are part of that group of people for whom taking such drugs is useless?
Another knot in the complicated mesh of cholesterol vs heart disease. To be solved....?
Jennifer Couzin-Frankel, May 2016 Why high ‘good cholesterol’ can be bad news