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Sunday 19 April 2015

What blood tests should I have for CV ?

This post taken from the website of Peter Brukner OAM, MBBS, FACSP, FACSM, FASMF, FFSEM is a specialist sports and exercise physician and the founding partner at the Olympic Park Sports Medicine Centre in Melbourne. Peter is a world renowned sports medicine clinician and researcher. He has recently been Head of Sports Medicine and Sports Science at Liverpool Football Club and is currently Team Doctor for the Australian cricket team. Peter is a staunch advocate of the low carb high fat diet. Read more here.

What blood tests should I have Doc?

This is a question I am frequently asked by patients interested in assessing their cardiovascular risk. Traditionally I guess the most popular screening tests have been a full blood count (FBC), fasting blood glucose (FBG) and a serum lipid profile.

In Australia (and most other countries) when you order a serum lipid profile you will receive a number of test results including Total Cholesterol, LDL-cholesterol, HDL-cholesterol, Triglycerides and they will usually give you the Total chol/HDL-chol ratio.

It is now generally accepted that the total cholesterol reading is not particularly relevant.

LDL-chol has always been considered important because of its relationship to cardiovascular disease, but it is too general a measure. Grouped into the LDL-chol level are particles of various sizes from the large fluffy (innocent) to the very small (dangerous) particles. One alternative is to measure particle size and see what proportion of the LDL is the small dense ones.

Fortunately there is very good correlation between the levels of small dense LDL particles and triglyceride levels, so it is sufficient to measure triglycerides. I consider triglyceride levels one of the really important blood tests. The other important lipid measurement is the HDL-cholesterol. Combining these two measurements gives me my favorite measure the Triglyceride/HDL-chol ratio (Trig/HDL).

So my preferred blood tests are

1. Triglycerides

Triglycerides have been shown to be a significant risk factor associated with cardiovascular (CVS) disease. As mentioned above they are also a very good surrogate measure of the dangerous small dense LDL particles. Most labs have the upper level of “normal” serum triglycerides at less than 1.5mmol/L (130 mg/dl) or even 2.0 mmol/L (180 mg/dl), but I would recommend less than 1.2mmol/L (100mg/dl).

2. HDL-cholesterol

Known as the “good” cholesterol, HDL is one of the lipoproteins that transports cholesterol. Levels of HDL- chol above 1.0 (40 mmol/L) are associated with decreased risk of CVS disease.

3. Triglyceride/HDL-cholesterol

This is my favorite measurement and obviously a combination of the first two. I like the ratio to be 1.2 (if measured in mmol/L) or less. If measured in mg/dl (USA) the ratio should be less than 2.5.

4. HbA1c

As mentioned above, the traditional measurement to assess blood sugar has been the fasting blood glucose level. This has largely been replaced now by the HbA1c which gives a good indication of the average serum glucose levels over the previous 3 months and is therefore not as susceptible to the fluctuations of serum glucose affected by food intake. HbA1c level should be <5.5%

5. C-reactive protein (CRP)

CRP is a general non-specific measure of inflammation in the body. As inflammation is now thought to be the instigating step in the development of atherosclerosis as well as involved in a wide range of diseases, the presence of inflammation is important to determine. CRP level should be <2.

6. Liver function tests (LFTs)

High carbohydrate diets are associate with the development of non-alcoholic fatty liver disease which can be best measured by a range of liver enzymes included in the standard LFT (ALP, GGT, ALT,AST) . The level of alanine aminotransferase (ALT) is the best indicator of fatty liver disease and should be less than 40IU/L.

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