Having Your Cholesterol Checked?
Today, the business of quick cholesterol testing in places such as hospital fairs and shopping malls is becoming common. Even your doctor may want to check your cholesterol while you're at the office for an unrelated appointment. How accurate these tests are depends, in part, on how it is taken and what is measured. Here are some factors to consider when checking your cholesterol:
1. The finger prick, where a small amount of blood is taken from the finger and analyzed by a portable machine, can only measure your total cholesterol. It has value in screening for high cholesterol levels of genetic origin, occasionally found in children, or very high levels, over 300, in the adult. However, for most individuals this test is of little merit considering the total cholesterol is a number which should be compared with other types of blood cholesterol.
2. A more complete blood test is best, and includes measuring specific types of cholesterol — the HDL (high density lipoprotein), and the LDL (low density lipoprotein), and sometimes other fats called triglycerides. When checking the level of triglycerides, always have this done after a 12-hour fast (no food or liquid for 12 hours, other than water), as eating usually raises the level of blood triglycerides.
3. The total cholesterol is not as significant as the ratio of total cholesterol to HDL. This number is the most important one, and should be below 4.5 for women and 5.5 for men. For example, if your total cholesterol is 210 and your HDL is 55, your ratio is: 210 divided by 55 = 3.8. That's a good number and a low risk for heart disease, although many people will look at the 210 cholesterol and think that's a bad number. On the other hand, suppose your total cholesterol is 180. You might think that's a good number. But if your HDL was only 30, your ration (180 divided by 30) would be 6.0—that's a bad number! It infers a high risk for heart disease.
4. It is not unusual for two competent labs to obtain different results from the same person. A 20% error is common, even within the same lab.
5. Other factors which may evoke errors should be considered.
… With the finger prick test, proper techniques in taking blood and using the equipment are vital. The finger should never be squeezed for blood, which dilutes the blood giving inaccurate results.
… With any methods, the patient should rest for five minutes or more before blood is taken, and the test should never be done standing.
… Be sure the equipment used has been standardized as recommended by the Centers for Disease Control.
… Factors which influence the results include time of year, viral infections, certain medications, recent weight loss or gain, and recent surgery.
One final word: a test result demanding any type of treatment should be repeated.