Cholesterol Test
Cholesterol Test
health.nytimes.com
Diagnosis
Blood tests can easily measure both HDL and overall cholesterol levels. It is very difficult to measure LDL levels by themselves, but LDL levels can be reliably calculated by subtracting HDL and triglyceride levels from total cholesterol. The exact formula is:
LDL = TOTAL CHOLESTEROL - HDL - TRIGLYCERIDES/5.
A blood test for cholesterol should include the entire lipoprotein profile: LDL, total cholesterol, HDL, and triglycerides. It is very difficult to measure LDL levels by themselves, but LDL levels can be reliably calculated using total cholesterol and HDL levels.
To obtain a reliable cholesterol reading, experts advise:
Avoid strenuous exercise for 24 hours before the test. Do not eat or drink anything but water for 12 hours beforehand. If the test results are abnormal, a second test should be performed between 1 week and 2 months after the first test. Home Tests. Tests are available for home use and in public locations, such as shopping malls and pharmacies. For example, the CholesTrak Test can be taken at home with results in 10 minutes, but it measures only total cholesterol. The BioSafe Cholesterol Panel Test is also a home test, but it needs to be sent to a laboratory. This test, however, is very accurate and provides a full lipid profile.
Skin Test
A new type of test measures cholesterol levels in the skin. High skin levels may indicate an increased risk for atherosclerosis and serious heart disease.
Screening Guidelines
General Screening Recommendations. Experts groups differ slightly on when screening should start, but the following are generally accepted recommendations:
Periodic cholesterol testing is recommended in all adults, but the major national guidelines differ on the age to start testing. Recommended starting ages are between 20 - 35 for men and 20 - 45 for women. Adults with normal cholesterol levels do not need to have the test repeated for 5 years unless changes occur in lifestyle (including weight gain and diet). Adults with a history of elevated cholesterol, diabetes, kidney problems, heart disease, and other conditions require more frequent testing. Selective screening of children who are at risk for high cholesterol and heart disease or familial hypercholesterolemia, which is genetically elevated cholesterol. Risk factors include having parents with total cholesterol levels greater than 240 mg/dL, or having a parent or grandparent who had symptomatic heart disease at age 55 or younger for men and age 65 or younger for women. Obese children with waist circumference between the 75th - 90th percentile are also at increased risk for cardiovascular and metabolic disorders and may need testing. Patients already being treated for high cholesterol should be checked every 2 - 6 months.