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Blood tests involve taking a small amount of blood from a vein, usually in your arm.

Blood tests involve taking a small amount of blood from a vein, usually in your arm.
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Guide to blood testing

3-minute read

Blood tests can be used to assess your general health, as well as help your doctor diagnose or monitor a range of conditions. Blood tests are generally accurate, but not perfect. This information helps you understand what is involved.

Before having the test

If you have been referred for blood tests, you might ask:

  • Do I really need to have these blood test?
  • What are the risks? What happens if the tests aren’t accurate?
  • What happens if I don't do anything?
  • What are the costs in time, effort and money?
  • How will I get the results and when?

Some tests require preparation (such as fasting) so it’s important to check whether you need to do anything special beforehand.

What happens during a blood test?

You'll usually need to go to a pathology collection centre. That might be in the same building as your doctor or elsewhere.

You'll have your details checked, and a small tourniquet put around your arm before a needle is inserted into your vein.

A small amount of blood is collected and put into one or more tubes and sent to a pathology service for analysis.

You'll need to keep pressure on the site where the blood was taken for a short while. Try not to use that arm too much for the rest of the day.

You might bleed and bruise at the site where the blood is taken. This is more common in people who have problems with blood clotting.

Some people get dizzy and faint. If you think this might happen, drink plenty of water and sit down for a while after your blood is taken. If you can, arrange for someone to help you get home or back to work.

Getting your results

If you want to know the results, make arrangements to ring or see your doctor. Some pathology services will send you a copy of your results.

What do the results mean?

To understand what your results mean, you should talk to your doctor. A result that is normal for one person could be abnormal for another.

Results only have meaning when you and your doctor take into account:

  • why you had the test done
  • your age and gender
  • your health
  • your medical, family and social history
  • your lifestyle
  • any medications you take
  • your occupation and ethnicity

Are the results always accurate?

Blood tests are generally accurate, but some can be wrong. A blood test can:

  • suggest something is abnormal when it isn’t, which is known as a 'false positive'
  • suggest something is normal when it isn’t, which is known as a 'false negative'.

Whatever the results, your doctor will take into account other aspects of your health before advising on what they mean.

Are there any blood tests I shouldn’t have?

Yes. There are many tests available that are either unproven, unreliable or unnecessary. Yet they all cost time and money. If the test cost isn’t covered by Medicare ask your doctor if it’s necessary for you.

If you don't mind reading detailed health information, then Choosing Wisely has collated a list of tests, treatments and procedures that medical experts think are unnecessary or unreliable.

What do blood tests cost?

Costs of various blood tests vary, but Medicare generally covers all or part of the cost. Most tests are bulk-billed. If money is a worry for you, call the laboratory (the number will be on your form) and ask how much the tests cost and how much Medicare covers.

More information

For more information about blood tests, and why you shouldn't panic if it looks like any are marked as abnormal, see Lab Tests Online.

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Last reviewed: June 2018

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