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.

The problem is that you cannot tell what your cholesterol levels (there are 2 main types of cholesterol) are by any means other than taking a blood test. A person with very a high level of cholesterol in their bloodstream will generally experience absolutely no adverse symptoms right up until their first cardiac arrest. Even if treated with cholesterol lowering drugs, they won’t actually feel any different at all.

Needless to say, waiting for a heart attack is not the best way of finding out whether your cholesterol levels are too high, because by then much of the damage has already been done. High cholesterol is a silent killer and the only way to detect it before it causes irreversible damage to your well-being is by periodic testing. Once you find out the hard way that your arteries have become clogged through years of unnoticed high cholesterol it is already too late – there may be few symptoms of high cholesterol per se, but the symptoms of resulting cardiovascular disease most definitely will intrude on your enjoyment of life.

So who should have their blood cholesterol levels checked? Pretty well everyone is the short answer, but obvious high priority candidates are those who are overweight or who take very little exercise, smokers, drinkers, anyone who favours a high fat diet, and most people over the age of 30. There is considerable evidence of a causal link between these specific factors and high cholesterol.

Young, fit and healthy people should also take a cholesterol test if there is a history of high cholesterol in their family, since although most of the cases seen these days are caused by environmental and lifestyle factors, there is also a genetic disorder commonly termed familial hypercholesterolemia (or FH) which is passed down through family lines. Certainly, if the incidence of premature cardiovascular disease features prominently in your family tree then FH could easily be the culprit.

What will a cholesterol test actually tell you? Most people and indeed medical practitioners refer to a single value, such as 5. This is in fact a summary of the 2 main types of cholesterol: HDL (often called “good cholesterol”) and LDL (characterized as “bad cholesterol”). HD stands for High Density, LD obviously for Low Density and the L prefix is short for Lipoprotein.

In general levels below 5 mmol/L are considered good, levels upto 6.2 are borderline (i.e. not good at all but not necessarily cause for alarm either), and values above 6.2 are treated as indicators of high risk for heart disease. There is an alternative scale which measures milligrams per decilitre and the boundaries are 200 and 240 mg/dL (corresponding to 5 and 6.2 mmol/L respectively).

If you have your cholesterol tested and the results fall in the low-risk bracket and there are no other factors weighing against you (i.e. you’re reasonably fit, maintain a healthy diet and haven’t noticed any trends towards sudden and untimely death among your biological relatives) then you really don’t need to be tested more than once every 5 years or so.

Those who fall somewhere in the borderline category should consider which of the known risk factors might be causing raised cholesterol levels and address them. It is well known that losing excess weight can correct a slightly high cholesterol reading without the need for further intervention. People who fit this borderline profile should also monitor their cholesterol levels much more frequently both in order to determine the effectiveness of measures to improve their levels and also to ensure that things aren’t deteriorating.

If you find yourself classified as high risk it’s important that you seek medical advice as to what may be the underlying cause of your condition and what treatment would be best. Obviously, if you find you have inherited FH then frankly there is no viable diet that can address this genetic disorder (though using this as an excuse to indulge in high fat food is akin to fighting fire with petrol).

In most cases, you will be prescribed a drug known as a statin. These vary in strength and your doctor will need to assess the amount of statin necessary to decrease and then maintain your cholesterol level below the approved limit (5.0 mmol/L). This is part educated guess and part trial and error – people react differently to different drugs and at the levels needed to treat cases of very high cholesterol the statins themselves can present a real risk of serious damage to muscle tissue and the liver.

Obviously, if this is you then the good news is that you should be able to easily reduce your cholesterol level well below 5.0 and keep it there quite effortlessly, simply by taking statins. The less thrilling news is that regular blood testing is going to be part of your life from now on – both to monitor cholesterol levels and check for any evidence of unwelcome side-effects from the statins.