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Results of Blood tests

Results from blood tests come in different forms, depending on the reason your blood was being tested.

If your test was to find out whether you have got a disease or infection such as HIV, your doctor should be able to tell you whether the result was ‘positive’ or ‘negative’. This depends on whether or not the antibodies to fight the infection were found in your blood. This is the same if you are being tested to find out if you have had vaccinations; if you have been vaccinated, the antibodies will be found in your blood.

If you had a test to look for abnormal red blood cells, for example in sickle cell anaemia, you will be told whether this was found. Your doctor will talk to you about what this means and whether you will need any treatment or further tests. Similarly, if the test was to find out whether you had too few of a type of blood particle (such as clotting factors or disease-fighting white blood cells), you will be told how many were found. Your doctor should then explain whether this is a normal or abnormal quantity, and will discuss what will happen next, such as any treatments you might need. 

Blood tests do not always give a definite, final answer. Sometimes it takes a long time for antibodies to a disease to appear, so for example with HIV you are advised to come back for a second test in several months time, to double check you are still negative. Your doctor will not usually get a clear result such as ‘positive’ or ‘negative’, but will have to interpret numbers and statistics that come back from the laboratory, so there is always a small chance that further tests will be needed to confirm a diagnosis. Even genetic tests are not always entirely trustworthy, because close relatives such as brothers and sisters can have many of the same inherited characteristics. If you are not sure about what your results mean, or want to know how accurate they are, ask your GP or hospital specialist for further information.

Sometimes getting results can be upsetting so if you are worried about the outcome of a test, take a trusted friend or relative with you. For tests such as HIV, you can be referred to a specialist counsellor.

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