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Blood tests have traditionally been 'fasting' and 'non-fasting...

Blood tests have traditionally been 'fasting' and 'non-fasting. I was informed recently that the evidence suggests that the results are similar in both cases, e.g. cholesterol levels. Is that correct?

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The answer

Thank you for your question in regards for the need of fasting when undergoing blood tests. A 2012 study showed that there was, indeed, minimal difference between a fasting and non-fasting cholesterol blood test. Whilst this stands true, one needs to be careful with the generalization of this to all the other tests that may require fasting.

A fasting blood test allows for your doctor to have a snapshot of your body without external interference from food, medication and other factors (you might be asked not to smoke or drink alcohol prior to some tests).

In regards to cholesterol we need to understand that there are two types of cholesterol, high-density lipoprotein (HDL) and low-density lipoprotein (LDL). As the name shows these are types of lipids. The study shows that there was no significant difference between these with fasting and non-fasting tests. The issue relies with the fact that the testing of cholesterol is, often, done in conjunction with tests for other lipids, namely triglycerides. These can be affected by food to an extent that your doctor might feel the need to recommend dietary/lifestyle changes.

If your main concern is the cholesterol you might be able to disregard the fasting factor.

Despite this, other tests, such as blood-glucose, triglycerides will most certainly require a fasting period to portray an accurate snapshot of your body. As a rule of thumb our recommendation is for you to follow your GP recommendations.

2012 Article about Cholesterol testing Fasting vs Non Fasting


High Cholesterol NHS Choices


Answered by the Health at Hand nurses