What is a blood test?

Blood tests are a type of pathology test that can be used to check your general health. They can help your doctor diagnose and monitor a range of conditions including:

• anaemia (low red blood cell count)
• infections
• nutrient deficiencies
• immune disorders
• cancers
• levels of certain medicines

Read more about specific types of blood tests to find out when they may be used.

Blood tests are generally accurate, but they're not perfect. This information can help you understand what is involved.

How and where can I get a blood test?

You need a referral from your doctor to get a blood test. They will give you a request form that you will need to give the pathology (blood sample) collector.

Most blood tests are taken in pathology collection centres. Your doctor can recommend a pathology collection centre close by. Often, the address will be on the request form that they give you.

Sometimes, your doctor will collect blood for testing in their clinic. Blood tests are also routinely collected in hospitals.

For most standard blood tests, you do not need an appointment. However, some tests may require booking in advance or might not be available at all collection centres. Contact your nearest pathology centre or ask your doctor for details.

How do I prepare for a blood test?

If you have a referral for a blood test, you might ask these questions:

• Why do I need these blood tests?
• What are the risks?
• What happens if the tests aren't accurate?
• What happens if I don't have the test?
• How much will the test cost and is it covered by Medicare?
• How will I get the results and when?
• What happens if the results aren't normal?

Some tests need preparation, such as:

• fasting (not eating for several hours beforehand)
• avoiding certain foods or drinks for a certain period before the test
• changing how or when you take a medicine or supplement before the test
• having the test at a certain time of day
• stopping smoking or drinking alcohol

It's important to check with your doctor or the pathology collection centre whether you need any special preparation.

If you have a needle phobia (fear) and find it difficult to have a blood test, speak to your doctor or pathology collector about ways to make the experience more comfortable for you.

How long does it take to get a blood test?

For most people, having a blood test is quick and easy and only takes a few minutes. Some specific blood tests may take longer. You can find out by calling the pathology collection centre in advance.

Depending on when and where you go for your test, the pathology collection centre may have a queue.

If you live in remote or rural Australia, you may have to travel further to get some blood tests.

What happens during a blood test?

Before having a blood test, the staff will check that your personal details on the pathology request form are correct.

Your blood sample will be taken by a trained professional. This might be a doctor, nurse or someone who is specifically trained to collect blood (phlebotomist).

The blood is usually taken from a vein in your arm. To take the blood, a tourniquet will be put around your arm and you may be asked to make a fist. A tourniquet is a band that stops or slows the flow of blood in your arm, so your veins can be seen and felt more easily.

A needle will then be inserted into a vein in your arm.

A small amount of blood is then sucked up into one or more tubes and sent to a pathology laboratory for testing.

After the needle is removed, you'll be asked to press on the site where the blood was taken until the bleeding has stopped. Try not to use that arm too much for the rest of the day and avoid heavy lifting. This reduces the chance of bruising.

Are there any risks or side effects from having a blood test?

Pain

It may hurt a little when the needle is inserted and removed from your vein. The tourniquet may also feel a little uncomfortable. For most people, the pain is only mild and only lasts a minute or so.

Bruising

The most common side effect of a blood test is bruising.

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.

To reduce the chance of bruising, you can apply an ice pack to the area.

Difficulty finding a vein

Taking blood can be more difficult in some people than in others. This occurs if your blood doesn't flow well during the test, or if you have veins that are more difficult to access. This may be due to variations in individual anatomy or a medical condition.

You can try the following to help improve your blood flow before having a blood test.

• Make sure you have enough to eat and drink in the days leading up to your blood test.
• Keep warm before and during your blood test.
• Go for a short walk before your blood test to get your blood flowing.

You should always check with your doctor or the pathology testing centre whether you need to do anything specific to prepare for your blood test.

Feeling faint

Some people faint or feel light-headed during or after a blood test. If you think this might happen, you should let the person taking your blood know beforehand. They may recommend you lie down while they take the blood sample.

If you feel light-headed, stay seated for a while after the blood test, and get up slowly. If you can, arrange for someone to help you get home or back to work.

What are the different types of blood tests?

There are many different types of blood tests. Your doctor may refer you for more than one test at a time, so several tubes of blood may need to be collected.

Some common blood tests include:

• blood glucose test
• full blood count
• HbA1c test (for blood glucose control, usually in people with diabetes)
• hCG test — human chorionic gonadotropin test (pregnancy test)
• kidney function tests
• liver function tests
• prostate specific antigen (PSA) test

Blood tests to check on your heart, blood vessels and blood clotting include:

• cardiac enzymes
• cholesterol and lipid tests
• D-dimer test
• international normalised ratio (INR) test

Blood tests to check for inflammation include:

• C-reactive protein (CRP) blood test
• erythrocyte sedimentation rate (ESR) test

Blood tests to check the levels of some vitamins and minerals in your blood include:

• calcium blood test
• folate test
• iron studies blood test
• magnesium blood test
• vitamin B12 test
• vitamin D test

Blood tests to check hormone levels include:

• oestrogen blood test
• testosterone blood test
• thyroid function tests

When and how will I get the results of my blood test results?

The results of most common blood tests are available within 1 to 2 days. Some blood tests take longer to process.

Ask your doctor when your results are likely to be ready and whether they will contact you about the result. They may recommend making a follow-up appointment to discuss your results.

Some pathology services will send you a copy of your results if your doctor asks them to on the referral form. Still, it is best to talk to your doctor to understand what your test results mean.

What do my blood test results mean?

What your results mean will depend on your personal situation and should be interpreted and explained to you by your doctor.

Blood test results only have meaning in the context of:

• the reason you had the test
• your age and sex
• your overall health
• your lifestyle
• any treatments or medicines you are taking, including complementary medicines and supplements

Some results are compared to reference intervals or ranges. These are a range of values that are considered generally normal for the population, but not necessarily for every individual. So if your results are highlighted as 'high' or 'low', it's important to check with your doctor whether there is actually a problem.

Are blood test results always accurate?

Blood tests are generally accurate, but sometimes they can be wrong.

A blood test can:

• suggest something is abnormal when it isn't — known as a 'false positive'
• suggest something is normal when it isn't — known as a 'false negative'

Whatever the results, your doctor will consider all aspects of your health before talking to you about what they mean. They may even refer you for more testing to make sure they understand your results correctly.

What do blood tests cost?

The costs of different blood tests vary.

Medicare covers all or part of the cost of most common blood tests. Many are bulk billed — this means that Medicare pays the full cost, so you don't have to pay anything.

Your doctor should explain if there will be an out-of-pocket cost involved. You can also call the pathology collection centre (the number will be on your request form) to ask how much your tests will cost and how much Medicare covers.

Resources and support

The Pathology Tests Explained website has many resources and fact sheets available if you need help or more information on blood testing.

The Royal College of Pathologists of Australia has useful fact sheets on a range of topics.