High blood cholesterol
Tens of millions of adults have high blood cholesterol. If you're among them, you may be on your way to heart disease. Because of its reputation as a risk factor for heart disease, people tend to think of cholesterol only in negative terms. But cholesterol is an important component of cell membranes and is vital to the structure and function of all of your body's cells. Cholesterol also is a building block in the formation of certain types of hormones.
When the levels of cholesterol and triglycerides, a blood fat, in your bloodstream become too high, your likelihood of developing cholesterol-containing fatty deposits (plaques) in your blood vessels increases. Over time, plaques cause your arteries to narrow, which impedes blood flow and creates a condition called atherosclerosis. Narrowing of the arteries that supply your heart with blood (coronary artery disease) can prevent your heart from getting as much oxygen-rich blood as it needs. This means an increased risk of a heart attack. Likewise, decreased blood flow to your brain can cause a stroke. Less blood flowing to your lower limbs may result in exercise-related pain or even gangrene.
The good news is that with the help of lifestyle changes and possibly medications, you may be able to lower your high blood cholesterol.
Signs and symptoms
There are no symptoms of high blood cholesterol. The only way to find out if you have high blood cholesterol is by having a blood test.
To circulate in your blood, which is mainly water, cholesterol and triglycerides — a form of fat — must be carried by proteins called apoproteins. A lipoprotein is a combination of a lipid — a fatty substance in the blood — and an apoprotein.
The main types of lipoproteins are:
Having a low level of LDL cholesterol and a high level of HDL cholesterol is desirable for lowering your risk of developing plaques and coronary artery disease.
You may have high LDL cholesterol as a result of genetic makeup or lifestyle choices, or both. Your genes can give you cells that don't remove LDL cholesterol from your blood efficiently or a liver that produces too much cholesterol as VLDL particles. Your genetic makeup can also result in too few HDL particles.
These lifestyle choices can cause or contribute to high levels of total cholesterol:
These factors increase the likelihood that high total cholesterol levels will lead to atherosclerosis:
Screening and diagnosis
A good way to detect high blood cholesterol early, so that you can take steps to improve your health, is to have a regular blood test to measure your cholesterol level. Some doctors recommend having your levels of HDL cholesterol and of triglycerides measured initially, along with your total cholesterol level. A typical blood-screening test measures:
Values for LDL cholesterol can be calculated from the other three values. You usually don't need a precise measurement of your LDL cholesterol level, but when it is needed, another blood test can specifically determine your LDL level.
Measuring only total cholesterol can be misleading because some people have low levels of HDL cholesterol and high levels of triglycerides, but normal or even high levels of LDL cholesterol. In these cases, a total cholesterol measurement might appear normal. You and your doctor would be unaware of the risk of heart disease posed by the abnormal levels that weren't measured. Even with a desirable total cholesterol level, if you have a low HDL level, you may be at increased risk of heart disease.
The results of blood tests for lipoprotein levels fall into optimal, near optimal, borderline high risk, high risk and very high risk categories. Desirable ranges for cholesterol levels vary depending on risk factors, such as your age, sex, family history and health condition. There's no magic number that separates risky levels from safe levels. Instead, experts have identified levels of lipids in the blood above which the risk of developing coronary complications is high enough to warrant lifestyle changes. Talk to your doctor about what level is appropriate for you.
Have your baseline cholesterol tested when you're in your 20s and then at least every five years. If your values aren't within desirable ranges, your doctor may advise more frequent measurements.
You can also purchase a home cholesterol test. These tests measure only total cholesterol, are less sophisticated than laboratory tests and may give unreliable results.
Children generally don't need to undergo cholesterol testing, unless there's a family history of early-onset heart problems.
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