What happens with cholesterol?

Cholesterol is an essential lipid, used to build the membrane of many of our cells. In addition, various steroids, bile acids and vitamin D are synthesized from cholesterol within the body. High cholesterol increases the chances of suffering from heart attacks and strokes. On the other hand, too low cholesterol is associated with depression that can even lead to suicide.

When someone says: I have had an analysis and it turns out that I have cholesterol, we should answer: If you didn’t have cholesterol, you’d be dead. What you have is high cholesterol.

Cholesterol circulates through the blood, bound to various types of lipoproteins. Depending on which lipoprotein, the effect of high cholesterol is different. When cholesterol is measured in a blood test, it is usually divided into four different numbers:

1. Good cholesterol (HDL, for high-density lipoprotein), so called because it blocks the harmful effects of bad cholesterol.
2. Bad cholesterol (LDL, for low-density lipoprotein), so called because it tends to form plaques that can clog the arteries.
3. VLDL cholesterol (for very low-density lipoprotein). Sometimes this number is given in the form of triglyceride concentration (triglycerides are lipids that help transport fat and glucose from the liver to the blood), which is five times higher. Sometimes both data are given, which is redundant.
4. Total cholesterol, which is obtained from the previous three using the following formula:

Total cholesterol = HDL + LDL + VLDL

Along with these four measurements, which are redundant, as the fourth can be obtained by adding the first three, reference values are also provided with the results that can be considered normal. In recent years, the maximum normality value for total cholesterol has been reduced. Until 2007, the normality limit was set at 250 or 260. In 2011 it was reduced to 220. Since 2012 it has dropped to 200. Using these reference values, some general medicine doctors prescribe statins (pills to lower cholesterol) to every patient with a total cholesterol level greater than 200 mg/dL. These pills can have serious side effects.

Let's look at the limits of normality for the various components of cholesterol, as they appear in an analysis carried out in 2014:

Test	Normality Limits
Total Cholesterol	100-200
HDL Cholesterol	>45
LDL Cholesterol	<155
VLDL Cholesterol	7-40

Suppose that a person has the three components of cholesterol exactly at the extreme of their normality limits. All three would be in the normal range. But then, what is the total cholesterol value for this person? Applying the previous formula, we get this:

Total cholesterol = 45 + 155 + 40 = 240

However, the previous table indicates a normal limit of 200 for total cholesterol. Is it reasonable that, although the three components are normal, the sum be highly abnormal? Note, in passing, that this maximum value of 240 is quite close to what was considered normal for decades, until 2007.

The answer to this discrepancy may lie in the recommendations of the American Heart Association, which take into account the heart risk of each patient to define cholesterol limits:

Heart risk	Dangerous LDL
Low	>160
Moderate	>130
Moderately high	>100
High	>70

The limit of 200 for total cholesterol may be reasonable if applied to a person with moderate or moderately high heart risk. Perhaps the reduction of this limit was due to the fact that doctors want to be in the safe side, and prescribe cholesterol-lowering pills to people who do not need them, despite their possible side effects. I think it would be better to reconsider. Each patient should be treated separately, taking into account the heart risk, the value of HDL cholesterol (which is more favorable the higher it is), as well as age and sex, which also influence normal cholesterol levels.

Cui prodest? Who benefits from this confusion? The pharmaceutical companies that sell more pills; analysts, who do a larger number of analysis; researchers, who will publish more articles...

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Manuel Alfonseca