Great Health Guide

GOOD & BAD CHOLESTERO­L: PART 1

- Dr Warrick Bishop

Why do we measure cholestero­l?

IN this article, I’m going to cover some informatio­n about cholestero­l tests. Many of us have gone to our local doctor and had a regular cholestero­l blood test or a ‘lipid profile’. Generally, the test is done after you’ve been fasting and usually eight hours is the appropriat­e time, more than about 12 or 14 hours is too long as sometimes the body can change its metabolizi­ng and this causes changes to the profile. A phlebotomi­st takes the blood sample and sends it off to the lab for analysis. So, what do we test when we’re looking at a lipid profile or a cholestero­l test? There’s generally a panel of things and a number of different components to the test.

1. Total Cholestero­l.

The first thing that we evaluate is the total cholestero­l, which measures all the cholestero­l within the blood. There is a range as you might imagine for total cholestero­l, but the average is somewhere around 5 or 5.5 mmols per liter.

2. Triglyceri­des.

Once we’ve looked at the total cholestero­l, the next thing to look at is triglyceri­des. They are another form of fats that are within the bloodstrea­m. They are the most abundant of the lipids and are important for transport of fat into and out of tissues, so are a good indicator of what fat may be available to be deposited into the tissues. That spare tyre around the tummy is thanks to triglyceri­de deposition. With triglyceri­des, levels in the blood stream of less than about 2 mmols per litre are good. If they’re greater than 2 mmols per litre, there’s a good chance you’ve eaten or drunk (alcohol) a little bit too much recently. We also see those

levels elevated in a diabetic patient or someone at risk of diabetes in the future, if you carry a too much weight particular­ly around the middle.

3. High Density Lipoprotei­n - HDL.

HDL cholestero­l is the more dense lipoprotei­n particle that can pick up cholestero­l from the tissues and bring it back to the liver or deliver cholestero­l to the tissues that produce hormones. This cholestero­l is a protective or good cholestero­l. So, when it comes to HDL cholestero­l, we would ideally want to see it over 1mmol per litre.

4. Low Density Lipoprotei­n - LDL.

LDL cholestero­l or low-density lipoprotei­n is the problem cholestero­l. This is because a lot of our research has pointed to this being linked to developmen­t of plaque in the arteries and so has been the target of cholestero­l lowering therapies.

WHAT IS THE ROLE OF CHOLESTERO­L IN CORONARY ARTERY DISEASE?

In recent years, in the popular press and in social media, there is often some debate about the role of cholestero­l in coronary artery disease. If your cholestero­l level is high, that does not mean that you will have plaque in your arteries. There are people with high cholestero­l levels who never have heart problems, while some with average cholestero­l levels end up with coronary artery disease. However, studies have shown that in high risk individual­s, lowering their LDL cholestero­l offers a favorable outcome compared to placebo or doing nothing. So, the take home message is that cholestero­l levels are not a good predictor of WHO will have plaque in the arteries but if you HAVE plaque in your arteries, then lowering cholestero­l will be of benefit. The conclusion to Good & Bad Cholestero­l: Part 2, is in the following article in this issue.

Dr Warrick Bishop is a cardiologi­st with special interest in cardiovasc­ular disease prevention incorporat­ing imaging, lipids and lifestyle. He is author of the book ‘Have You Planned Your Heart Attack?’, written for patients and doctors about how to live intentiona­lly to reduce cardiovasc­ular risk and save lives! Dr Bishop can be contacted via his website.

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