You’ve probably had your cholesterol levels checked, or could very easily — it just takes a blood test. But what do these numbers mean, and what are they supposed to be?
Types of cholesterol measured
Well, naturally you’d think that a laboratory test for cholesterol would simply tell you how much cholesterol you have in your blood. And it does, but wait: There’s more than one type of cholesterol in your blood. These types include:
- Total cholesterol
- HDL cholesterol
- LDL cholesterol
Total cholesterol is all of the cholesterol in your blood that can be measured. It’s also the most commonly tested type of cholesterol.
HDL cholesterol is the “good” cholesterol bound to high-density lipoproteins. Having more of it means you’re more likely to have a lower risk of heart disease.
LDL cholesterol is the “bad” cholesterol bound to low-density lipoproteins. You’re better off with lower levels of LDL cholesterol, because it’s associated with a higher risk of heart disease.
Note that total cholesterol doesn’t equal HDL cholesterol plus LDL cholesterol. This is because there are still more types of cholesterol, which we won’t talk about here.
Your cholesterol numbers
Cholesterol is measured as milligrams of cholesterol per deciliter of blood, which is abbreviated like this: mg/dL.
Often, your total cholesterol is the only type tested. Or you may have both your total cholesterol and your HDL cholesterol tested at the same time.
If your total cholesterol is:
|200 mg/dL or less||Desirable cholesterol level.|
|Between 200 and 239 mg/dL||Borderline-high cholesterol level.|
|240 mg/dL or more||Too high.|
If your HDL cholesterol is:
|Less than 40 mg/dL||Too low.|
|More than 40 mg/dL||Beneficial especially if it’s above 60 mg/dL.|
Based on the results of your total cholesterol (and HDL cholesterol, if it was measured) your doctor will decide whether your LDL cholesterol should be tested, too. You’ll probably receive this test if:
- Your total cholesterol is high, or
- Your HDL cholesterol is too low, or
- Your total cholesterol is borderline-high, and your HDL cholesterol is too low; or
- Your total cholesterol is borderline-high, and you have other risk factors for heart disease.
If you are 20 years old or more, have no heart disease, and your LDL cholesterol is:
|Less than 100 mg/dL||Desirable.|
|100 – 129 mg/dL||Near optimal/above optimal.|
|130 – 159 mg/dL||Borderline high.|
|160 – 189 mg/dL||High.|
|190 mg/dL and above||Very high.|
If you already have heart disease, then your LDL cholesterol should be 100 mg/dL or less.
Your cholesterol ratio
Sometimes you’ll be given your cholesterol results as a ratio of total cholesterol to HDL cholesterol. (This is the same thing as saying total cholesterol divided by HDL cholesterol.) According to the American Heart Association (AHA), the ratio should be below 5:1, with the optimal amount being 3.5:1 (3.5 to 1).
It’s also possible to divide LDL cholesterol by HDL cholesterol to obtain a ratio. (This is the same thing as saying the ratio is LDL cholesterol to HDL cholesterol.) According to the Mayo Clinic, in this case, the ratio should be below 5, with the optimal amount below 3.
However, the AHA recommends that absolute numbers for cholesterol (as discussed above) be used, not ratios. The reason is because the AHA believes absolute numbers give physicians a better idea of what type of treatment is needed by the patient, than ratios can.
Your triglycerides are another biochemical substance in the blood that affects your risk for heart disease. Most fat in food, as well as in your body, is present in the form of trigylcerides. High levels of triglycerides are a matter of concern and are linked to the risk of heart disease, just as with cholesterol.
If your triglycerides are tested, here is how you can interpret the numbers, according to the Third Report of the Expert Panel on the Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults:
|Less than 150 mg/dL||Normal.|
|150 – 199 mg/dL||Borderline.|
|200 – 499 mg/dL||High.|
|More than 500 mg/dL||Very high.|
Calculating LDL cholesterol
According to the Mayo Clinic, if your triglycerides are normal, it is possible for your doctor to calculate your estimated level of LDL cholesterol from your tested levels of total cholesterol and LDL cholesterol. The equation your doctor might use is:
LDL cholesterol = total cholesterol — (HDL cholesterol ” [triglycerides/5])
Remember, only your doctor should determine the best way to evaluate and interpret your cholesterol levels. Speak to your doctor if you have any questions about your cholesterol levels or the best way, given your individual situation, to reduce your risk for heart disease.