What are the other Names for this Test? (Equivalent Terms)
- Blood Cholesterol Test
- Total Cholesterol Test
What is Cholesterol Test? (Background Information)
Cholesterol is a kind of fatty substance that plays an important role in the human body. The body is capable of producing cholesterol and some of it is obtained from the diet. Cholesterol helps in:
- Forming the covering of all cells (plasma membrane) in the body
- The formation of some hormones (chemical messengers involved in regulating bodily functions)
- The production of bile acids that help in absorbing fats and some vitamins from food
Although, cholesterol is essential for life, too much of it can lead to its deposition on the blood vessel walls. This can cause a narrowing of the blood vessels, or a thickening of their walls (atherosclerosis). This can cause many serious problems, including increased risk of heart attacks and strokes.
- Increased consumption of fatty substances (containing cholesterol, saturated or trans unsaturated fats) raises blood cholesterol
- Some individuals also have inherent conditions, which predispose them to high cholesterol levels
Some of the cholesterol circulates in blood as part of a particle, called lipoprotein (compounds made of proteins and fatty substances, such as cholesterol, triglycerides, and phospholipids). These lipoproteins are classified based on their densities into:
- High-density lipoproteins (HDL)
- Low-density lipoproteins (LDL)
- Very low-density lipoproteins (VLDL)
Amongst these, HDL is otherwise termed as “good cholesterol”, while LDL is referred to as the “bad cholesterol”. This is because HDL carries cholesterol from the tissues to the liver for disposal, whereas LDL deposits it in the tissues and organs.
A test for cholesterol mainly serves as a screening test, to detect those at risk of developing heart disease. It is usually performed as a part of what is called a lipid profile- tests for total cholesterol, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and triglycerides.
What are the Clinical Indications for performing the Cholesterol Test?
- Cholesterol levels are estimated routinely, as a component of preventive healthcare, and administered to adults at least once every 5 years
- In children and young adults, testing is recommended twice, once between ages 9-11 and then between the ages 17-21 years
- The frequency of testing increases in individuals being treated for high cholesterol levels, to monitor progress
Cholesterol levels are also measured frequently in those having one or more (major) risk factors for heart disease, which include:
- Age: Men over 45 years, women over 55 years
- High blood pressure
- History of heart disease in an immediate family member (especially if in a male relative under 55 years, or a female relative under 65 years)
- Being overweight or obese; for obese younger individuals, cholesterol levels may have to be measured, as often as once every 2 years
The American Academy of Pediatrics recommends Cholesterol Testing for high-risk children, as early as 2-10 years.
How is the Specimen Collected for Cholesterol Test?
Sample required: Blood
Process: Sample is drawn through a needle inserted into the vein (arm).
Preparation required: When cholesterol levels are measured as part of a lipid profile test, 9-12 hours fasting, before testing is advised. Only the consumption of water is allowed during this period.
What is the Significance of the Cholesterol Test Result?
Cholesterol Test results can be divided into 3 groups depending on the risk for heart disease:
Desirable: Low risk for heart disease
- Adults: Cholesterol level below 200 mg/dL (5.18 mmol/L)
- Young adults: Cholesterol level below 190 mg/dL (4.92 mmol/L)
- Children and adolescents: Cholesterol level below 170 mg/dL (4.40 mmol/L)
Borderline: Moderate risk for heart disease
- Adults: Cholesterol level of 200 to 239 mg/dL (5.18 to 6.18 mmol/L)
- Young adults:Cholesterol level of 190-224 mg/dL (4.92-5.80 mmol/L)
- Children and adolescents: Cholesterol level of 170-199 mg/dL (4.40-5.16 mmol/L)
High risk for heart disease
- Adults: Cholesterol level more than or equal to 240 mg/dL (6.22 mmol/L)
- Young adults: Cholesterol level more than or equal to 225 mg/dL
- Children and adolescents: Cholesterol level more than or equal to 200 mg/dL (5.17 mmol/L)
When the total cholesterol values are high, the physician may order a complete lipid profile, to measure the amounts of good (HDL-C) and bad (LDL-C) cholesterols.
When a patient is being treated for high cholesterol, blood cholesterol measurements help in guiding treatment. The target levels of the lipids are set by the physician and based generally on LDL levels. The target values are:
- HDL-C: More than 40 mg/dL
- Less than 70 mg/dL, for individuals with existing heart disease, or those having a very high risk (metabolic syndrome- obesity, diabetes, high blood pressure )
- Less than 100 mg/dL, for those having high risk of heart disease
- Less than 130 mg/dL, for those with having risk of heart disease
The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results, based on the overall clinical scenario.
Additional and Relevant Useful Information:
- Drugs, such as anabolic steroids, oral contraceptives, vitamin D, and beta blockers, increase cholesterol levels
- Pregnancies also tend to increase cholesterol levels. Hence, in pregnant women, cholesterol levels should be measured, 6 weeks after child birth
- Stress and illness lower cholesterol levels; hence,in such cases, the cholesterol levels should be measured 6 weeks after recovery from any illness
Certain medications that you may be currently taking may influence the outcome of the test. Hence, it is important to inform your healthcare provider, the complete list of medications (including any herbal supplements) you are currently taking. This will help the healthcare provider interpret your test results more accurately and avoid unnecessary chances of a misdiagnosis.