Measuring Cholesterol

by Jo-Ann Heslin, MA, RD, CDN on February 5, 2004 · 0 comments

The National Cholesterol Education Program (NCEP) recommends that all adults over age 20 be screened for cholesterol at least once every 5 years. But what does that mean?

A cholesterol screening can tell you a great deal — your total cholesterol, HDL cholesterol, LDL cholesterol, and a “ratio.”


Total cholesterol, is just that: The total amount of cholesterol in a given volume of blood. Ideally, you want your level to be below 200, to lower your risk of heart disease.

Blood cholesterol is measured in milligrams (mg). The number of milligrams (mg) of cholesterol in 1 deciliter (dl), or slightly less than half a cup, is the measure of how much cholesterol is in your blood. For example, 180 mg/dl = 180 milligrams of cholesterol per deciliter of blood. To make things simpler, your doctor may give you just the number, 180.

But it’s a little more complicated than that. Cholesterol, a fat-like substance, is coated with a protein so it can travel in your blood, which is mainly water. The combination of fat and protein is called a lipoprotein.

LDLs (low-density lipoproteins) are the major cholesterol carriers. If too much LDL cholesterol circulates in the blood, it can stick to the walls of arteries leading to the heart and brain. This could eventually form plaque — thick, hard, artery-clogging deposits. A clogged artery leading to the heart can cause a heart attack. A clogged artery leading to the brain can cause a stroke. This is why LDL cholesterol is often referred to as “bad” cholesterol. A desirable levels of LDL cholesterol is less than 100. The lower your LDL, the lower your risk of heart disease.

About one-third of the blood’s cholesterol is carried by HDLs (high-density lipoproteins). Experts believe HDL cholesterol carries cholesterol away from the arteries back to the liver, where it is broken down and removed from the body. Because this may slow down the growth of plaque, HDL cholesterol is referred to as “good” cholesterol. Levels under 40 are considered too low.

Having low LDL cholesterol and high HDL cholesterol reduces your risk of developing plaques and lowers your risk for heart disease.

Your “ratio” is determined by dividing HDL cholesterol into total cholesterol. If your total cholesterol is 200 and your HDL cholesterol is 50, your ratio is 4:1. A ratio below 5:1 is good. The optimum is 3.5:1.

It’s important to get a full lipid profile – total cholesterol, HDLs and LDLs –because measuring just cholesterol can be misleading. A person could have normal cholesterol values but high LDL (bad cholesterol) values.


Total Cholesterol
Good Under 200
Borderline 240 or higher
Too high 240 or higher
LDL Cholesterol HDL Cholesterol
Optimal under 100 Low under 40
Near or above optimal 100 to 129 High 60 or higher
Borderline high 130 to 159
High 160 to 189
Very high 190 or higher

Source: National Cholesterol Education Program, Third Report of the Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III), 2001.

For more information on watching your cholesterol, look inside The Cholesterol Counter, 6th Ed. by Annette B. Natow, PhD, RD and Jo-Ann Heslin, MA, RD.

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