Introduction
Cholesterol is one of the most important substances in the human body. It is found as a waxy, fat-like substance in the blood. Humans get cholesterol from two main sources, and depending on the source, cholesterol is named; blood cholesterol and dietary cholesterol.
- Blood cholesterol comes from the liver of the human body and is produced enough for maintaining good health.
- Dietary cholesterol comes from food (mainly meat, fish, cheese, and eggs) and too much of it can cause adverse effects on health.
What Are the Functions of Cholesterol?
Cholesterol function determines one's health. The human body cannot function adequately without the proper functioning of cholesterol substances. Cholesterol helps mainly with the following:
- Build up human cells and cell membranes.
- Produce bile acid, which is necessary for digestion.
- Produce certain vitamins (for example, Vitamin D).
- Produce certain hormones (for example, glycoprotein, and sex hormones)
How Is Cholesterol Found in Blood?
Cholesterol has a complex chemical structure. Cholesterol binds with proteins called lipoproteins to circulate in the blood. Lipoproteins may be small or big in size. They can transport fat in the bloodstream with ease. The important lipoproteins are:
- Low-Density Lipoprotein (LDL) - Carry cholesterol from the liver to body parts.
- High-Density Lipoprotein (HDL) - Carry excess cholesterol from the blood by extracting from arteries and low-density lipids back to the liver.
- Very Low-Density Lipoprotein (VLDL) - Carry triglyceride and cholesterol to body tissues for function.
Why Is Cholesterol Test Important?
High cholesterol levels make an individual more prone to diseases (for example, stroke, heart attack) or complicate existing health conditions (for example, blood pressure, diabetes) for an individual. In addition, the human body does not show any specific signs or symptoms if one has high cholesterol unless it is too late (fatal). Hence, routine blood work on cholesterol is important to keep the levels at bay.
Apart from cholesterol, triglyceride is the other important fat. The body converts unused calories into triglycerides, which are stored and later released by hormones to give energy to the body between meals. Triglyceride also has a complex chemical structure and binds with lipoproteins to circulate in the blood.
Who Needs a Cholesterol Test?
Doctors recommend getting a routine blood test once aged 30 and above. But, considering factors such as family history (for example, high cholesterol, stroke) and risk factors (for example, obesity), one may need blood tests from childhood.
According to the National Heart, Lung, and Blood Institute (NHLBI), for children born with a family history of a high incidence of heart attack, stroke, or high cholesterol, the first cholesterol test is advised as early as two years of age. Later at nine to 11 years, and repeated every five years. Healthy individuals aged 45 years and above are recommended to do cholesterol tests at yearly intervals.
Apart from a routine blood test, certain health conditions require half-yearly or yearly cholesterol tests as the individuals may pose a higher risk for heart disease or stroke.
Such conditions are:
- High blood pressure.
- Obesity (overweight).
- A daily habit of smoking or alcohol consumption.
- Unhealthy diet (high-fat content) and lifestyle (no exercise).
When on cholesterol medications, it takes a minimum of six weeks for the medication to control the cholesterol levels. Cholesterol tests may be repeated after eight weeks of medication, or the doctor may request a repeat test every six months or yearly, depending on the individual's health condition.
What Does a Cholesterol Test Measure?
A cholesterol test measures the cholesterol and triglyceride in the blood. It is also called a lipid panel or lipid profile test.
Each type of cholesterol comprises; fat, lipoprotein, and triglyceride in varying concentrations. The difference in combination gives rise to different types of cholesterol. It is measured in;
- mg/dL - milligrams (mg) of cholesterol per deciliter (dL) of blood.
- mmol/L - millimoles (mmol) of cholesterol per liter (L) of blood.
The cholesterol test includes a group of tests for three types of cholesterol and a triglyceride test.
1. Low-Density Lipoprotein Cholesterol- LDL Cholesterol
- Cholesterol is bonded to low-density lipoprotein.
- Excess can cause build-up in arterial walls (atherosclerosis).
- These may rupture and cause heart attack or stroke.
- Hence called the "bad" cholesterol.
- Ideal LDL cholesterol levels for 6 to 10 years - Less than 110 mg/dL.
- Ideal LDL cholesterol levels for 10 to 19 years - Less than 110 mg/dL.
- Ideal LDL cholesterol levels for adults (19 years and above) - Less than 100 mg/dL.
2.High-Density Lipoprotein Cholesterol- HDL Cholesterol
- Cholesterol bonded to high-density lipoprotein.
- Carry excess cholesterol from arteries and blood back to the liver.
- Prevents atherosclerosis hence called "good cholesterol".
- Ideal HDL cholesterol levels for 6 to 10 years - More than 45 mg/dL.
- Ideal HDL cholesterol levels for 10 to 19 years - More than 45 mg/dL.
- Ideal HDL cholesterol levels for adults (19 years and above)- More than 50 mg/dL.
3.Triglycerides
- Bonded to very low-density lipoproteins.
- Too much triglyceride in the body puts the individual at risk for various heart diseases.
- Individuals who smoke or drink alcohol often, or have an unhealthy diet, and are obese (overweight) are more prone to high triglyceride in the blood.
- Ideal triglyceride for 6 to 10 years - Less than 75 mg/dL.
- Ideal triglyceride levels for 10 to 19 years - Less than 90 mg/dL.
- Ideal triglyceride levels for adults (19 years and above) - Less than 150 mg/dL.
4. Total Cholesterol
- It is the total of low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and 20 percent of triglycerides (very low-density lipoprotein cholesterol).
- High total cholesterol indicates a high risk for heart attack and stroke.
- Ideal total cholesterol level for 6 to 10 years - Less than 170 mg/dL.
- Ideal total cholesterol level for 10 to 19 years - Less than 170 mg/dL.
- Ideal total cholesterol level for adults (19 years and above) - Less than 200 mg/dL.
- Very Low-Density Lipoprotein Cholesterol - VLDL Cholesterol.
- Carry mainly triglyceride but also cholesterol in the blood.
- Not recorded often and is calculated as 20 percent of triglyceride measurement.
- Normal range - 2 to 30 mg/dL.
What Are the Instructions for Cholesterol Tests?
Cholesterol tests involve drawing a minimum blood sample from the individual, which is sent to a laboratory for testing. Generally, it is done in the morning as the individual is asked to fast (no food or liquid except water) for at least 8 to 12 hours before the blood test. This is done to avoid errors in the result that may happen due to the fat content in the meal eaten last.
Some studies do recommend having a blood test without fasting for better assessment. It is claimed that it is more effective since humans generally do not fast for 12 hours and snack and often eat throughout the day. Hence a non-fasting blood test for cholesterol is a better option.
With a better understanding of history, current medications, and risk factors that concern the individual, a doctor can guide if a fasting or a non-fasting blood test is ideal for one.
If on medications, individuals are recommended to take them only after the blood test since most medicines are taken after food, and some may affect test reports.
Conclusion
Cholesterol is essential for good health. Monitoring, if one has good or bad cholesterol, is necessary to maintain good health. Check cholesterol levels, and change diet and lifestyle to keep cholesterol under control.
