So you’ve tested your cholesterol levels but what exactly do those numbers mean and what are HDL and LDL cholesterol and why is the ratio between them important?

First things first. High cholesterol (or hypercholesterolemia to use its medical name) is usually considered to mean high levels of LDL cholesterol in the blood.

Cholesterol is a type of fat (known as lipid) and is regarded as being made up of 5 main components: chylomicrons, HDL (high density lipoprotein), IDL (intermediate density lipoprotein), LDL (low density lipoprotein) and VLDL (very low density lipoprotein). Of these, only HDL (often referred to as “good cholesterol”) and LDL (”bad cholesterol”) are considered for modern cholesterol tests.

Cholesterol cannot actually travel through the bloodstream on its own so it binds with proteins, hence the term “lipoprotein”. The “density” describes the ratio between lipids and proteins, so LDL is mostly lipids (fat) with a low amount of protein and HDL is the reverse and has “spare capacity” to absorb additional lipids.

Most cholesterol in your blood stream is LDL and it is absolutely vital to maintaing health, but too much can cause deposits to form that progressively constrict and harden the main arteries, leading eventually to heart disease, strokes and other unwelcome outcomes. HDL absorbs excess cholesterol in the bloodstream (including LDL) and returns it to the liver where it is metabolised and reused or excreted.

For quite some time now, many if not most low-cost cholesterol tests have measured only the total cholesterol count, the amount of HDL and triglycerides (basically fat absorbed from food) present in the bloodstream and estimated the other constituents (working on the basis that VLDL accounts for about 45% of the triglyceride count, and LDL equates to total cholesterol minus HDL and VLDL). This is simply due to the cost of direct measurement of LDL and provides workable results, though it is important not to eat for 12 hours prior since triglyceride levels are obviously highly affected by food intake.

Quite a few home cholesterol test kits in fact only give a total cholesterol count, though there are home test kits that do provide additional data about HDL, and occasionally LDL, concentrations in the blood. Home cholesterol test kits sometimes provide accurate figures that map to standard units of measure (such as mmol/L or mg/dL) and sometimes just yield an indication such as a change of color which suggests whether the result is high, medium or low.

For total cholesterol, the medically accepted range is:

above 6.2 mmol/L = high; 5.0 to 6.2 mmol/L = medium; below 5.0 mmol/L = low.

A similar scale that measures milligrams per decilitre is:

above 240 mg/dL = high; 200 to 240 mg/dL = medium; below 200 mg/dL = low.

If you also have access to your HDL reading then you can calculate your “risk factor” (how exposed you are to the possibility of developing cardiovascular problems). This is simply total cholesterol divided by HDL and the risk tables are as follows:

For men, above 4.6 = high; 3.6 to 4.5 = medium; at or below 3.5 = low;
For women, above 3.6 = high; 3.1 to 3.5 = medium; at or below 3.0 = low;

So for example, a man with total cholesterol of 6 mmol/L and HDL of 2 mmol/L has a risk ratio of 6:4 or 1.5 which is low, whereas a woman with total cholesterol of 4.5 mmol/L and HDL of 1.0 mmol/L has a very high risk ratio of 4.5:1 or 4.50. In this latter case, diet and in particular exercise might bring her HDL up to 1.5 mmol/L which brings the ratio back to a safe 4.5:1.5 or 3.0.

If your cholesterol home testing kit provides (or at least estimates) LDL data then you can also monitor your HDL:LDL ratio, where the goal is to keep this ratio above 0.3 and preferably above 0.4 (for example HDL 1.2 mmol/L and LDL 3.0 mmol/L).

Although the ratios between these HDL and LDL and total cholesterol provide reasonable indicators of risk, medical advice also cautions against a standalone LDL value above 3.0 or or an HDL value below 1.0.

As you can see then, measuring your cholesterol levels can present a surprisingly sophisticated picture of your general state of health now and your chances of living out a full and healthy life in the future. In the modern world, where to be honest many of us take too little exercise and eat too much food (much of it high in fat), regular cholesterol testing is an important monitoring tool and one that is these days reasonably cheap and easily accessible, especially online.




1 Comments

  1. VLDL Cholesterol Range, July 14, 2009:

    I haven’t ever bothered about cholesterol and the related problems but I feel, I should give it a thought. Thanks for the information on cholesterol.

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