A cholesterol ratio is the result of one cholesterol value divided by the value of another revealing a significant relationship between the two.
To better understand its meaning, another definition/explanation would be:
It is the ratio of the blood level values of various types of cholesterols (lipoproteins and triglycerides) in relation to each other. The lab values of these ratios could be good or bad and explain your risk to coronary artery disease (CAD). The amount of risk helps your doctor to chalk out the course of treatment. A healthy cholesterol denotes a healthy heart.
The medical fraternity is, however, divided on the importance of these ratios and some feel that individual values of the various cholesterol levels better suit the purpose when planning treatment.
Most others feel that these cholesterol ratios are significantly beneficial and give you an idea of the chances (risks) of a person developing heart disease. They are commonly included in your lipid profile tests carried out in a laboratory.
Cholesterol is waxy and sticky in nature and cannot dissolve in blood. It, therefore, needs a medium to carry it around through the blood stream.
That medium is the protein on whose back it piggy rides and moves with it through the blood to deliver cholesterol to the body tissues and cells. This combination of cholesterol and proteins is called the lipoproteins.
Your lipid profile or cholesterol blood test report comes with the individual blood level values of the following:
Total cholesterol is the sum total of all cholesterols in the blood including HDL, LDL, and triglycerides.
Therefore, if you have the numbers of HDL, LDL, and the triglycerides, you can calculate total cholesterol by adding the values of these three lipids.
Total cholesterol would be HDL plus LDL plus 20% of triglycerides. If you had LDL of 100 mg/dl, HDL of 60 mg/dl, and triglyceride level of 150 mg/dl, then the equation would read: 100 + 60 + (150/5) = 190 mg/dl, which is a healthy value.
Low-density lipoprotein or LDL
LDL is referred to as the bad cholesterol because it is the one, which floats around in the bloodstream and any excess of it (indicated by its high readings in the lipid profile) over the years sticks on the inner wall of the arteries.
This can narrow the lumen of the arteries and further even occlude the artery. High levels of LDL therefore, put you at a higher risk of developing a heart attack.
The narrowing and hardening of the arteries is called atherosclerosis.
Don’t be misled by this misnomer. Low density doesn’t mean low density of the cholesterol part, but rather it is the protein part that is of lower density making more room for the cholesterol, which becomes denser in LDL.
Similarly, the HDL means more density of the protein fraction and low density of the lipo (fat or cholesterol) faction.
High-density lipoprotein or HDL
HDL is referred to as the good cholesterol because it transports the excess LDL in the blood to the liver. From the liver, it is subsequently transported to the intestines through the bile for excretion.
Besides removing the excess LDL from the blood, it also helps to remove any cholesterol deposits from the arterial wall; hence the name “good cholesterol”.
Triglycerides are a type of fat with very low-density cholesterol lipoprotein (VLDL). They are a different type of fat from cholesterol.
The body converts the extra calories from the food that you eat into triglycerides, which are stored in the fat cells. Triglycerides are the main storage form of fat in the body. When required, the hormone glucagon releases the triglycerides when there is a need for energy.
Eating high saturated fat and carbohydrate foods can increase your triglyceride levels in the blood. This is called hypertriglyceridemia and is a high-risk factor for heart disease and stroke.
You could check out this post on the healthy, borderline and the undesirable levels of all these cholesterols in both American and European units to compare your report and see where you stand.
Healthy levels will mean having lower levels of total cholesterol, LDL and triglycerides and higher levels of HDL.
Cholesterol ratios are derived at by dividing the blood level value of one of cholesterol with another. The ratios help define the risk of the individual to heart disease.
Following are the various ratios that are provided with your cholesterol testing report.
Types of cholesterol ratios
1) Total Cholesterol/HDL ratio
2) LDL/HDL ratio
3) HDL/LDL ratio
4) Triglyceride/HDL ratio
Total Cholesterol/HDL Ratio
This ratio is derived at by dividing the total cholesterol (TC) value by the HDL value. This ratio can be 5:1 on the higher side of the normal, but ideally, it should be below 3.5.
For example, taking the higher limit of normal values, if your total blood cholesterol level is 200 mg/dl and your HDL value is 40 mg/dl, then your total cholesterol: HDL ratio will be 5.1.
A higher ratio means higher than normal total cholesterol levels, which means more bad cholesterol (LDL) and triglyceride levels in the blood and low good cholesterol (HDL) levels.
This ratio helps in predicting atherosclerosis and subsequent risk of ischemic heart disease.
A higher ratio will indicate substantial changes in the metabolic pointers, which predict ischemic heart disease risk and relate to the insulin resistance syndrome.
LDL/HDL Cholesterol Ratio
Certain laboratories also provide the ratio of LDL to HDL for the purpose of predicting the chances of heart diseases. This ratio can be below 3.5 but, ideally, it should be below 2.5. A low LDL: HDL ratio indicates a healthy heart with a low coronary disease risk.
This ratio is often calculated to estimate the risk of coronary heart disease (CHD). Studies have suggested that a high LDL/HDL ratio combined with high triglyceride levels (hypertriglyceridemia) is associated with the highest CHD risk both in men and women.
However, the LDL/HDL ratio may not be so effective in evaluating the CHD risk in obese diabetes patients with high triglyceride and low HDL levels.
HDL/LDL Cholesterol Ratio
This ratio divides the HDL blood value by the LDL value. The value of this ratio can be above 0.3. Ideally, however, this HDL: LDL ratio should be above 0.4, which indicates a healthy lipid profile.
If your good cholesterol level (HDL) is high, the bad cholesterol levels (LDL) have a lesser chance to increase your chances of heart disease.
This ratio particularly becomes important if your HDL and LDL levels are high to evaluate cardiac risk in relevance to treatment.
Triglyceride/HDL cholesterol ratio
This is probably the most important ratio to watch out for in evaluating cardiac risk.
An optimal TC: HDL ratio would be 2:1, meaning that if your triglyceride levels are 100 mg/dl, your HDL cholesterol should be 50 mg/dl.
- TG/HDL ratio less than 2 is ideal
- TG/HDL ratio above 4 is too high
- TG/HDL ratio above 6 is much too high
High triglyceride levels often accompany low HDL levels thereby increasing the ratio. As the ratio value increases, your chances of developing heart disease and stroke start picking up.
According to one study, TG/HDL level above 4 is the most powerful independent precursor of coronary artery disease.
How do you rate the importance of the cholesterol ratios?
According to Doc’s opinion, relying solely on the value of the bad cholesterol (LDL) may be misleading to gauge the risk of heart disease.
For example, obese people, diabetics with elevated lipid profile and metabolic syndrome (increased body weight, fat accumulation around the abdominal organs and increased insulin resistance) are often found to have elevated triglycerides, low HDL and near to normal LDL values.
However, in spite of low LDL levels, these people are at a very high risk of developing cardiac disease.
Therefore, the wisdom of relying on the individual levels of one type of cholesterol raises serious doubts. In such cases, the TG/HDL ratio will help identify the cardiac and stroke risk.
Your lipid test report will come with the cholesterol ratio and your health provider will determine your chances of getting heart disease by studying the test report. This becomes valuable in coursing the line of treatment.