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Cholesterol functions

Cholesterol refers to a diverse group of fats that serve a number of necessary functions in the body. Cholesterol helps keep cells from freezing, helps absorb fat soluble vitamins, serves as an antioxidant, and is the precursor for several hormones in the body. Like anything, cholesterol in excess can cause grave problems. I’ll spend a couple of columns talking about cholesterol as it is a topic on everyone’s mind.

About half of all Americans die of some type of heart disease, usually a heart attack. Stroke, another problem that can be caused by high cholesterol, comes in at number three for causes of death. Heart attacks most often come from the closure of one of the heart’s own blood vessels, and that usually stems from a rupture of a plaque largely composed of cholesterol. Cholesterol plaques can cause havoc wherever they are; strokes, heart attacks, arterial clots of the arms, legs, and intestines can all be caused by plaques and plaque rupture. Therefore treatment of cholesterol can have large consequences for a person’s lifespan, as you have a 1 out of 2 chance of dying from plaque in your heart arteries.

Cholesterol, being a fat, is not soluble in water. If there is too much cholesterol in the blood, it will settle out in artery walls. If you’ve ever seen fat collect on the top of a soup left in the refrigerator, then you’ve got the idea of what a plaque look like. That plaque in an artery is covered by a thin cap, and when it ruptures, a clot occurs. The resulting blockage stops the flow of blood to that part of the body, which then dies. The results can easily be fatal.



Cholesterol plaques start in childhood as fatty streaks, and grow into plaques over time until they cause problems. Different processes can cause plaque growth to speed up or slow down. Anything that raises the amount of cholesterol causes faster growth. High blood pressure, diabetes, and smoking cause plaque growth. Lowering cholesterol, exercise, and weight loss can cause slowing, arrest, or even regression of cholesterol plaques. Diabetes and smoking are particularly powerful plaque builders, and I see very early and very disastrous outcomes in diabetic patients who smoke. In my mind, there are very few things more deadly than that combination.

There are four main types of cholesterol reported: total cholesterol (TC), LDL cholesterol (aka ‘bad’ cholesterol), HDL cholesterol (aka ‘good’ cholesterol) and triglycerides (TG). Research in the past focused on TC, but now most efforts seem focused on LDL cholesterol. Other forms of cholesterol do count, and are part of the total package, although LDL cholesterol levels seem to be the most linked with survival. LDL cholesterol is called “bad cholesterol” because it is the type that deposits cholesterol in plaques. HDL cholesterol is called “good cholesterol” because it removes cholesterol from plaques. Triglycerides are an important secondary risk factor, and can contribute to plaque formation.




Cholesterol level goals are based on the risk of elevated cholesterol, which are somewhat individualized. An otherwise healthy 50 year old man without any health problems may do fine with an LDL level of 140, whereas the same man after a heart attack would live longer if his LDL was less than 100. The goals for cholesterol levels (chiefly LDL) are dependent upon risk factors. The major risk factors include known coronary artery disease, peripheral arterial disease (plaques in the arteries of the extremities), diabetes (Type 1 or Type 2), abdominal aortic aneurysm, or symptomatic carotid artery disease. Chronic kidney disease likely will (and should) be included with those in the future. Any of these risk factors confer close to a 1 in 5 or greater chance of having coronary heart disease. Any of these risk factors therefore require the most stringent control of LDL cholesterol to prevent death from heart disease, and get the most benefit out of treatment.

Cigarette smoking, high blood pressure, family history of premature heart disease, low HDL (less than 40 mg/dL), and age (men>45, women>55) all count as risk factors. The more risk factors, the lower the limits for LDL cholesterol. There are 3 basic goal numbers to remember: 100/130/160. Anyone with a major risk factor should be under 100, anyone with two or more risk factors should be under 130, and everyone with or without risk factors should have an LDL less than 160. This is a very broad-brushed expression of the goals, and I would need a book to sit down and go over all of the factors that go into the decision as to when to treat and what goal is appropriate. You and your doctor need to come up with an appropriate goal depending on your individual situation.

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I’ll write more about ways to lower cholesterol in the next column. You can e-mail me with questions at nicholas.browningmd@gmail.com.


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