What do my blood test results mean?

This question cannot be answered in general terms because your blood test results are specific to you. Your GP or the healthcare professional who arranged the test needs to interpret the results because only they have all the information necessary to do so.

For example, if your blood glucose (sugar) is tested and the result is low, this could be a sign of Addison’s disease (a condition that affects the adrenal glands).

However, if you have diabetes, it’s more likely to mean you’ve taken too much diabetes medication. Without knowing what medical conditions you have and what medication you’re on, the test results could be misinterpreted. 

Also, only your GP or consultant will know why you needed the blood test and what other tests you’ve had. It may be that all of your test results need to be assessed together.

For example, a full blood count can be used to measure all the different types of blood cells in the sample and diagnose anaemia (lack of red blood cells). However, without also looking at the results of your tests for ferritin (a protein that stores iron), vitamin B12 and folate, it won’t be clear what’s causing your anaemia and therefore what treatment you need. 

Different laboratories

Results for the same type of test can be expressed differently by different medical laboratories. This is because laboratories have different:

  • equipment
  • testing methods
  • reference ranges

Other factors that can affect test results

Your test results can also be affected by your age, your sex, when the test was carried out, for example morning or evening, your diet, and many more factors.

This means that your test results will be different to someone else’s, even if they have the same medical condition as you.

It’s important to follow any instructions your healthcare professional gives you before the test, for example not to eat or drink. For more information, see Can I eat and drink before having a blood test?

If you have any questions about your test results, you should ask your GP or the healthcare professional who arranged the test.

Read the answers to more questions about operations, tests and procedures.

Further information:

Page last reviewed: 05/02/2013

Next review due: 04/02/2015