Cholesterol testing is big business, which perhaps explains why it is so widespread. Certainly the actual point of testing the blood cholesterol of large numbers of the population has little benefit and is little to do with science. Cholesterol testing has a place, and in a research setting it can be highly useful. However, in research more expensive tests and finer detail are extracted from the testing process making it relevant. The tests for total cholesterol that are common in the medical setting are actually quite useless. Here are seven reasons why.
1. Total Blood Cholesterol is Meaningless
Measuring total cholesterol in the blood is pointless. This is because is is quite a weak indicator for cardiovascular disease. In fact in certain groups, particularly the elderly and in women, higher levels of total cholesterol can be associated with a decreased risk of mortality. Extrapolating ranges for total cholesterol levels to the population as a whole is therefore quite pointless unless it takes into account the person being tested, which of course never happens.
2. Low Density Lipoprotein (LDL) is A Better Biomarker Than Total Cholesterol
Some tests now include the LDL fraction. The LDL fraction is a better biomarker for cardiovascular disease than total cholesterol, with high levels of LDL increasing the risk of cardiovascular disease. However, LDL is made up of different particles that can be subgrouped into the small dense fraction and the large buoyant fraction. Only the small dense LDL fraction is associated with cardiovascular disease but clinical tests do not differentiate between the two.
3. What About High Density Lipoprotein (HDL)?
Some clinical tests now measure levels of HDL as well as LDL and total cholesterol. The HDL fraction is actually protective of cardiovascular disease and so the ratio between the HDL and LDL fraction is a better predictor of cardiovascular risk compared to either LDL or total cholesterol in isolation. However, without knowing with sort of LDL dominates the reading (small dense or large buoyant) you cannot accurately predict cardiovascular risk.
4. Lipoprotein(a) is Highly Atherogenic
There is another lipoprotein particle that is almost never mentioned and which will not be included in a clinical test. Lipoprotein(a) is highly atherogenic and is a very strong predictor of cardiovascular risk. Even more so that the HDL to LDL ratio. Its exclusion is problematic because even with a normal level of blood cholesterol, high concentrations of lipoprotein(a) would increase your risk of cardiovascular disease significantly. Some researchers claim lipoprotein(a) has been mistaken for LDL in studies, confusing the matter further.
6. Homocysteine Levels
Homocysteine is a metabolite of methionine metabolism. High homocysteine blood levels are a strong predictor of cardiovascular disease. Homocysteine is not routinely tested for and a person could have normal levels or cholesterol, a favourable HDL to LDL ratio and still be at high risk of cardiovascular disease because of elevated plasma homocysteine levels. Unless a homocysteine test is undertaken, it is difficult to predict cardiovascular risk.
7. Cholesterol is Associated with Cardiovascular Disease, But Does Not Cause It
High levels of total cholesterol and an unfavourable LDL to HDL ratio (favouring the small dense LDL particle) are risk factors for cardiovascular disease. However, they do not cause, but are merely associated with it. The cause of cardiovascular disease and lipoprotein changes are likely insulin resistance. Receiving a diagnosis and taking a pill to lower cholesterol levels therefore does nothing to reduce the risk of cardiovascular disease without addressing the underlying insulin resistance.
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