What is a high cholesterol blood test?

Key Points

• A high cholesterol blood test is a blood test that detects various lipids in the blood: mainly cholesterol and triglycerides. It can help diagnose hypercholesterolemia or triglyceridemia and monitor the effectiveness of lipid-lowering therapy.
• High cholesterol blood test can be done using fingertip blood or from venous blood.
• The normal values (or attainment values) for lipids used are different for different groups of people (e.g., healthy people, people with diabetes, people with coronary heart disease), so ask your doctor what the test results mean to you.

What is a high cholesterol blood test?

High cholesterol blood tests are a general term for cholesterol, triglyceride (TG) and lipids (phospholipids, glycolipids, sterols, steroids) in the blood serum, the main clinically relevant lipids are cholesterol and TG. Lipids are insoluble in water and must bind to special proteins called apolipoprotein (Apo) to form lipoproteins (Lp). Lipid testing is the detection of lipids and lipoproteins. Lipoproteins = lipids + apolipoproteins, because lipids are not water soluble and must be bound to proteins to be soluble in the blood. Therefore, the triglycerides and cholesterol measured clinically are the sum of triglycerides and cholesterol contained in all lipoproteins in the plasma.

Lipid sources are endogenous and exogenous, with exogenous sources mainly coming from food, such as meat, eggs and dairy products. Cholesterol is an important substance that makes up cell membranes and synthesizes hormones. Triglycerides are mainly used to store and provide energy for the body.

Higher lipid levels increase the risk of heart disease, myocardial infarction and stroke.

Why should we do a high cholesterol blood test?

(1) Lipid testing helps to check the risk of heart disease and atherosclerosis (hardening, narrowing and blockage of blood vessels).

(2) It can detect lipid abnormalities and get timely treatment. Lipid abnormalities usually have no clinical symptoms and patients are often unaware of their elevated blood lipids. By detecting elevated blood lipids through high cholesterol blood test and providing timely treatment, the chance of heart disease can be reduced; if one has heart disease, by lowering blood lipids, the incidence of heart attack can be reduced and the mortality rate of heart disease can be reduced.

(3) Helps to observe the effect of treatment. If the patient is normally being treated through low-fat diet, exercise and lipid-lowering drugs, the effect of treatment can be observed through lipid testing.

What preparations are needed before performing high cholesterol blood test?

(1) The following are not suitable for testing: severe infection, surgery, trauma, heart attack and pregnancy. It is recommended that the test be performed after 2 months.

(2) Avoid eating high-fat foods the night before the test.

(3) Do not drink alcohol within 24 hours prior to the test.

(4) Avoid taking drugs that affect the test results. Some western drugs, herbal medicines and nutritional supplements can affect the test results, so please consult with medical personnel before the lipid test.

How is the high cholesterol blood test performed?

For heparinized or EDTA venous whole blood, mix the specimen well and collect the specimen (35 μL or 10 μL) into a plastic/glass capillary transfer tube or pipette. Apply it to the center area of the specimen application area of the test strip. Do not touch the test strip with the pipette or tube. Blood samples must be tested within 8 hours of collection.

Wipe off the first drop of blood. Apply gentle pressure to obtain the second drop of blood. Use a capillary transfer tube or pipette to collect capillary blood. To use a capillary transfer tube, bring the tube slightly down and touch the tip of the capillary transfer tube to the blood sample. The capillary action will automatically draw the blood sample to the fill line and stop.
Note: The capillary transfer tube will automatically fill. Make sure the blood covers the vent of the tube or it will be difficult to squeeze the blood out.

Do not squeeze the capillary transfer tube while sampling. Align the tip of the capillary tube with the center hole of the specimen application area of the test strip to apply a second drop of blood (35 μL or 10 μL). Note: Do not touch the test paper with the capillary transfer tube or pipette. Capillary blood should be tested immediately after collection. The use of a capillary transfer tube or pipette is recommended to obtain accurate results.

Interpretation of high cholesterol blood test results

(1) Low-density lipoprotein cholesterol (LDL-C): Cholesterol-rich lipoprotein that transports cholesterol synthesized by the liver into the circulation, causing an increase in plasma cholesterol levels, which can lead to the formation of atherosclerosis over time, and is the main lipid risk factor for atherosclerosis. "The new 2019 European guidelines expand the coverage of people at very high risk of cardiovascular disease and provide more detailed cardiovascular risk stratification, setting LDL-C control targets for the corresponding population.

(2) High-density lipoprotein cholesterol (HDL-C): a lipoprotein containing small amounts of cholesterol. It carries cholesterol from surrounding tissues back to the liver for processing, prevents the deposition of free cholesterol on extrahepatic tissue cells, and therefore reduces plaque formation, prevents and delays the development of atherosclerosis, and is one of the protective factors against coronary heart disease, and is considered to be the "good cholesterol".

HDL-C at <40 mg/dL in men and <50 mg/d in women increases the risk of cardiovascular disease; at >=60 mg/dL, it is beneficial and reduces the risk of cardiovascular disease.

(3) Triglycerides (TG): TG is insoluble in water and combines with proteins to form lipoproteins, which circulate in the blood. Its main role is to store and supply energy. When TG is less than 150mg/dL (1.7mmol/L) it is good for the body, when it is greater than this value it is not good for health and also increases the risk of cardiovascular disease.

(4) The main causes of increased LDL, triglycerides and total cholesterol or decreased HDL are:

Single or multiple gene mutations, smoking, lack of exercise, excessive intake of saturated and trans fats (saturated fats are found in butter, whole milk, red meat and some fried fast foods. Trans fats are found in some fried fast foods and many processed foods, especially cookies and similar baked goods), being overweight, hypothyroidism, and taking certain medications such as steroids, receptor blockers, or birth control pills.

What if the high cholesterol blood test results are abnormal?

The high cholesterol blood test results are only part of the assessment and should be considered in conjunction with past medical history, physical signs and current health status. Sometimes it is necessary to give advice on lifestyle improvement including diet and exercise, sometimes it is necessary to take medication, and sometimes it is necessary to repeat the test for abnormal test results. Therefore, if you have an abnormal lipid test, talk to your doctor and ask questions such as: whether additional testing is needed; treatment options; and lifestyle, dietary or other changes that may be needed.

References：

1. Cholesterol test

See also:

1. Cholesterol care