Hyperholesterolemia definition
Cholesterol is a fatty substance (a lipid) that is an important part of the outer lining (membrane) of cells in the body of animals. Cholesterol is also found in the blood circulation of humans. The cholesterol in a person's blood originates from two major sources; dietary intake and liver production. Dietary cholesterol comes mainly from meat, poultry, fish, and dairy products. Organ meats, such as liver, are especially high in cholesterol content, while foods of plant origin contain no cholesterol. After a meal, cholesterol is absorbed by the intestines into the blood circulation and is then packaged inside a protein coat. This cholesterol-protein coat complex is called a chylomicron.
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.
Still, 37 million American adults have high blood cholesterol levels, and 105 million have cholesterol levels that are higher than desirable (hypercholesterolemia). If you're one of these people with this largely preventable condition, you may be on your way to heart disease.
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. It's estimated that if there were a 10 percent reduction in cholesterol levels throughout the U.S. population, the rate of heart disease would drop by 30 percent.
Signs and Symptoms
In its preliminary stages, high cholesterol generally occurs without any symptoms. For this reason, screening through routine blood tests is crucial for early detection. In its advanced state, however, high cholesterol may result in any of the following:
Fat deposits in the tendons and skin (called xanthomas)
Enlarged liver and spleen (which the healthcare provider may feel on exam)
Severe abdominal pain as a result of pancreatitis (this happens if triglycerides deposit in the pancreas, which may occur when triglyceride levels are 800 mg/dL or higher)
Chest pain and even a heart attack (this may occur when enough cholesterol has built up in blood vessel walls to block the flow of blood in the heart)
Causes
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:
Low-density lipoprotein (LDL). LDL cholesterol is sometimes called "bad" cholesterol because it transports cholesterol to sites throughout your body, where it's either deposited or used to repair cell membranes. But like hard water causing lime to build up inside plumbing, LDL cholesterol promotes accumulation of cholesterol in the walls of your arteries.
High-density lipoprotein (HDL). HDL cholesterol is sometimes referred to as "good" cholesterol because it helps clear excess cholesterol from your body.
Very-low-density lipoprotein (VLDL). This type of lipoprotein is made up of mostly triglycerides and small amounts of protein and cholesterol.
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.
Causes of high total and LDL cholesterol levels include:
- Hereditary hyperlipidemia (Types IIa or IIb)
- Diets high in saturated fats and cholesterol
- Liver disease
- Underactive thyroid
- Poorly controlled diabetes
- Overactive pituitary gland (a gland in the brain that helps control hormones in the body)
- A kidney disorder called nephrotic syndrome characterized by elevated cholesterol, loss of protein in the urine leading to low levels of protein in the blood, and excessive fluid retention causing swelling
- Anorexia nervosa
- Medications such as progestogens, cyclosporins, and thiazide diuretics
Diagnosis
Since most people have few if any symptoms of hypercholesterolemia (another term for high cholesterol), blood screening is very important. An initial blood test is done to check a "random" measurement of total and HDL cholesterols, meaning that the test is performed at any time during the day, regardless of what has been eaten. Those with abnormal levels (total cholesterol more than 200 mg/dL or HDL less than 40 mg/dL), will go on to have a test called fasting lipid profile (in which the person being tested refrains from eating for 8 to 12 hours, usually overnight, prior to the test). The fasting test will indicate whether or not total cholesterol levels fall within the normal range (between 140 and 200 mg/dL), are moderately high (between 200 and 240 mg/dL), or if they are in the very high range (240 mg/dL or greater). This blood test also reveals the levels of LDL, HDL, and triglycerides. According to guidelines released by the National Cholesterol Education Program (NCEP), the optimal level for LDL cholesterol depends on whether you have heart disease or not and whether there are other risk factors present for heart disease (such as diabetes and high blood pressure). The optimal level for HDL for all people (healthy or otherwise) is a measurement higher than 60 mg/dL; low levels are 40 mg/dL and below.
Treatment Approach
Lifestyle changes are the first steps you can take to improve your blood levels of cholesterol and triglycerides. These include changes in diet, regular exercise and avoiding smoking. If you've made these important lifestyle changes and your total cholesterol — especially your level of LDL cholesterol — remains high, your doctor may recommend prescription medication.
Before recommending medication, your doctor may weigh many variables — your changeable risk factors, your age, your current health and the drug's side effects. If you need a medication to improve your cholesterol levels, chances are you may need it for many years.Your LDL cholesterol level is usually the deciding factor.
Medications to improve blood cholesterol levels include:
- Resins
- Triglyceride-lowering drugs.
- Statins.
- Cholesterol absorption inhibitor
- Cholesterol absorption inhibitor-plus-statin combination
