Cholesterol is a key to understanding coronary vascular disease

Cholesterol is found in the fats of the bloodstream and the cells. Having it is a normal and important part of a healthy body, but when it becomes too high, it poses a significant threat.

By: Dr. Elliot Krauss
   This week is National Lab Week. To celebrate the importance of laboratory tests and increase public awareness about the benefits of having one of the most simple and effective lab tests done, we will focus on coronary vascular disease and its link with cholesterol.
   CVD is the number-one killer in America, claiming twice as many lives as cancer. Almost one-third of CVD deaths occur in individuals without any prior symptoms of the disease. The risk factors include: family history, smoking, high blood pressure, a high-fat diet, obesity, lack of exercise, diabetes and elevated chemical factors such as cholesterol. After a patient completes the lab tests and the results are in, physicians can determine the patient’s level of risk factors. This is a wonderful health tool.
   To help prevent heart attacks, it is important to understand cholesterol. Cholesterol is a soft, waxy substance that is found in the fats throughout the bloodstream and the body’s cells. Having cholesterol is a normal and important part of a healthy body. Its purpose is to form cell membranes, some tissues and some hormones. When the level of cholesterol becomes too high, it poses a significant health threat. The risk of CVD increases and thus, the risk of a heart attack.

   The body manufactures some cholesterol, and people get more through animal products in the diet. This includes meats, poultry, fish, eggs, butter, cheese and whole milk. Plant-based foods such as fruits, vegetables and cereals contain no cholesterol. Because cholesterol, like other fats, cannot dissolve in the blood, it is carried through the bloodstream by lipoproteins. This is where different types of cholesterol come in.
   Low-density lipoprotein, or LDL cholesterol, is known as the "bad" cholesterol. When there is too much LDL cholesterol circulating in the blood, it can slowly build up in the walls of the arteries that go to the heart and brain. It can join with other substances to form thick, hard deposits known as plaque. If the blood flow to part of the heart is blocked by a clot that forms where the plaque is, it can cause a heart attack. If the blood flow to part of the brain is blocked, it can result in a stroke.
   The "good" cholesterol is high-density lipoprotein, or HDL cholesterol, that travels away from your arteries. About one-third to one-fourth of blood cholesterol is carried by this scavenger cholesterol away from the arteries and back to the liver, where it is passed from the body. When the HDL level is high, it means that the body is doing its job properly. If the level is low, is cannot clean the system as well. It is believed that having high levels of HDL cholesterol can reduce your risk of heart attack.
   The third type of cholesterol is a very low-density lipoprotein, or VLDL cholesterol, which is bad and correlates with trigylcerides. Triglyceride is a form of fat that is made in the body and also comes from food. Many people who are obese, have heart disease or are diabetic tend to have high triglyceride levels, and this can be an independent risk factor for CVD.
   When the levels of LDL, HDL and triglycerides are tested in the lab, the results are calculated and a person is given his or her total cholesterol, or Tchol, level. Remember, however, that the Tchol includes both the "bad" cholesterol LDL as well as the "good" cholesterol HDL. Therefore, it is important to know the individual test results, and not just the total.
   One cannot discuss cholesterol without discussing numbers. When the numbers come back from the lab, the Tchol number is given the most attention. When it comes to Tchol, LDL and Triglycerides, the lower the number, the better off you are. The opposite is true of HDL. Here are the desired levels:
   Tchol less than 240 mg/dL, LDL less than 160 mg/dL, Triglycerides less than 200 mg/dL, HDL greater than 35 mg/dL.
   It is estimated that about 20 percent of the U. S. population has blood cholesterol levels greater than 240. This puts them at twice the risk of heart attack as people who have a cholesterol level of 200 mg/dL. About a third of American adults are in the borderline group of 200-240, while almost half of adults have total cholesterol levels below 200 mg/dL.
   All of these tests are believed to be most accurate when they are done on an outpatient basis since they can vary greatly due to the stresses of hospitalization. For screening tests, it is desirable to perform the lipid profile as a fasting test, first thing in the morning, after an overnight fast, without alcohol use in the past 24 hours. Alcohol tends to raise triglycerides, which is why it is important to abstain before the test. Labs will measure Tchol, HDL and triglycerides. From the triglycerides, the LDL is calculated. The lab may also perform Tchol, HDL and direct measurement LDL any time of the day, but you will not be able to measure triglycerides because they go way up with eating.
   There are three new lab tests which all involve taking samples of blood from the patient: The first is Lipoprotein (a) or Lp(a). The second is Homocysteine. The third is CRP or high-sensitivity C-Reactive Protein.
   Patients showing elevated levels of lipoprotein(a) run an increased risk of CVD regardless of other factors. Levels can be reduced with niacin and estrogen hormonal treatment in post-menopausal women. If homocysteine levels are high, vitamin supplements B12, B6 and folate can help reduce them. Elevated levels of CRP indicate inflammation, possibly in the blood vessels themselves, and this may play a role in developing CVD. CRP is really a marker that helps identify people who are at risk.
   Treatment involves taking medication and improving your diet. Lipitor and Zocor are a new class of drugs called statins which lower the LDL cholesterol, but have no effect on Lp(a), so they are not the only answer. Improving diet can help dramatically. A high-fat diet is one of several risk factors that patients can modify. Others include tobacco smoke, physical inactivity, obesity, and diabetes mellitus. To help your body defend itself against coronary vascular disease, have a routine physical and ask your physician to order lab tests that check your blood cholesterol levels. By the time you are between the ages of 40-45, it is useful to get a baseline reading. This allows you to modify your risk factors. Do it for yourself and for your family.
   Dr. Elliot Krauss is a pathologist on staff at The Medical Center at Princeton. This article was prepared in collaboration with Lorraine Seabrook. Health Matters appears Fridays in the Lifestyle section of The Princeton Packet and is contributed by The Medical Center at Princeton.