blood cholesterol test

[صيدلاني سوداني]

?Why Get Tested


To screen for risk of developing heart disease


?When to get tested


Adults should be tested once every five years or more frequently if being treated for high cholesterol or have one ormore risk factors for heart disease. Children and adolescents with risk factors should also have their cholesterol level checked.


?Sample Required


A blood sample drawn from a vein in the arm or a fingerstick


?Test Preparation Needed


If you are having this test performed as part of the Lipid profile, you will need to fast for 9-12 hours before the sample is collected; only water is permitted.




?What is being tested


Cholesterol is a substance (a steroid) that is essential for life. It forms the membranes for cells in all organs and tissues in your body. It is used to make hormones that are essential for development, growth, and reproduction. It forms bile acids that are needed to absorb nutrients from food. A small amount of your body’s cholesterol circulates in the blood in complex particles called lipoproteins. These lipoproteins include some particles that carry excess cholesterol away for disposal (see HDL-C, good cholesterol) and some particles that deposit cholesterol in tissues and organs (see LDL-C, bad cholesterol). The test for cholesterol measures total cholesterol (good and bad) that is carried in the blood by lipoproteins.
Your body produces the cholesterol needed to work properly, but the source for some cholesterol is your diet. If you have an inherited predisposition for high cholesterol levels or if you eat too much of the foods that are high in cholesterol, saturated fats, and trans unsaturated fats (trans fats), then levels of cholesterol in your blood may increase and have a negative impact on your health. The extra cholesterol in your blood may be deposited in plaques on the walls of blood vessels. Plaques can narrow or eventually block the opening of blood vessels, leading to hardening of the arteries (atherosclerosis) and increasing your risk of numerous health problems, including heart disease and stroke.

Monitoring and maintaining healthy levels of cholesterol is important in staying healthy.



?How is the sample collected for testing


Most often, a blood sample is collected from a vein in your arm. Sometimes cholesterol is measured using a drop of blood collected by puncturing the skin on a finger. A fingerstick sample is typically used when cholesterol is being measured on a portable testing device - for example, at a health fair.



?Is any test preparation needed to ensure the quality of the sample


If a cholesterol test is to be performed alone, it is not necessary to fast. However, if it is to be performed as part of a lipid profile, as it often is, then fasting for 9-12 hours before the test will be required; only water is permitted.




?How is it used


Cholesterol is different from most tests in that it is not used to diagnose or monitor a disease but is used to estimate risk of developing a disease — specifically heart disease. Because high blood cholesterol has been associated with hardening of the arteries (atherosclerosis), heart disease, and a raised risk of death from heart attacks, cholesterol testing is considered a routine part of preventive health care.



?When is it ordered


Cholesterol testing is recommended as a screening test to be done on all adults at least once every five years. It is frequently done in conjunction with a routine physical exam. It is usually ordered in combination with other tests including HDL-C, LDL-C, and triglycerides — often called a lipid profile.
Cholesterol is tested at more frequent intervals (often several times per year) in patients who have been prescribed diet and/or drugs to lower their cholesterol. The test is used to track how well these measures are succeeding in lowering cholesterol to desired levels and in turn lowering the risk of developing heart disease.

Cholesterol testing may be ordered more frequently for those who have one or more risk factors for heart disease. Major risk factors include:

Cigarette smoking
Age (men 45 years or older or women 55 years or older)
Hypertension (blood pressure of 140/90 or higher or taking high blood pressure medications)
Family history of premature heart disease (heart disease in an immediate family member—male relative under age 55 or female relative under age 65)
Pre-existing heart disease or already having had a heart attack
Diabetes mellitus
For those under 20 years of age and at low risk, cholesterol testing is usually not ordered routinely. However, screening for high cholesterol as part of a lipid profile is recommended for children and youths who are at an increased risk of developing heart disease as adults. Some of the risk factors are similar to those in adults and include:

Family history—history of high cholesterol or heart disease in close relatives, particularly if occurring before age 55 in women or 65 in men. If the family history is not known, a cholesterol test is recommended, especially if other risk factors are present.
Being overweight or obese—when the youth’s body mass index (BMI) is at or above the 85th percentile, cholesterol testing is recommended. The BMI should be calculated at least once a year by the youth’s health care provider. For an obese youth (one whose BMI is at or above the 95th percentile), laboratory tests to measure cholesterol levels may be recommended every 2 years.
Consuming excessive amounts of cholesterol, saturated fats, and trans fats
Diabetes mellitus
High blood pressure (hypertension)
Smoking cigarettes
High-risk children should have their first cholesterol test between 2 and 10 years old, according to the American Academy of Pediatrics. Children younger than 2 years old are too young to be tested. If the initial results are not worrisome, the fasting test should be done again in three to five years.




?What does the test result mean


For adults, in a routine setting where testing is done to screen for risk, the test results are grouped in three categories of risk:
Desirable: A cholesterol below 200 mg/dL (5.18 mmol/L) is considered desirable and reflects a low risk of heart disease.
Borderline high: A cholesterol of 200 to 239 mg/dL (5.18 to 6.18 mmol/L) is considered to reflect moderate risk. Your doctor may decide to order a lipid profile to see if your high cholesterol is due to the amount of bad cholesterol (high LDL-C) or good cholesterol (high HDL-C) in your blood. Depending on the results of the lipid profile (and any other risk factors you may have), your doctor will decide what to do.
High Risk: A cholesterol greater than or equal to 240 mg/dL (6.22 mmol/L) is considered high risk. Your doctor may order a lipid profile (as well as other tests) to try to determine the cause of your high cholesterol. Once the cause is known, an appropriate treatment will be prescribed.
The risk categories for children and adolescents are different than adults. Talk to your child’s pediatrician about your child’s results.

In a treatment setting, testing is used to see how much cholesterol is decreasing as a result of treatment. The goal for the amount of change or the final (target) value will be set by your doctor. The target value is usually based on LDL-C.