Blood Tests

Blood tests help diagnose diseases and illnesses and monitor your progress.

What are blood tests?
Why do I need blood tests?
What are the risks of having blood tests?
How do I prepare for blood tests?
What happens during blood tests?
What happens after blood tests?

What are blood tests?

Blood tests help diagnose diseases and illnesses and monitor your progress. They can also detect levels of some drugs. If you need blood tests, a small sample of your blood is collected, sent to a laboratory and analysed.

Why do I need blood tests?

You’ll usually need a blood test if your doctor wants to find out more about your health, or thinks you may have an illness. The results of your blood tests can help your doctor answer questions like:

  • Are your heart and kidneys working as well as they could be?
  • Are your treatments, including medications, giving you the best results?
  • Are you at risk for heart disease?
  • Is your blood at risk of clotting?

What are the risks of having blood tests?

Blood tests are very common tests. There are very few risks or side effects, but you might feel a sting or mild discomfort during the test.

How do I prepare for blood tests?

You usually don’t need to prepare for a blood test. Sometimes, you may not be able to eat for up to 8 hours before the test begins (this is called fasting). Your doctor will let you know if you need to fast before your blood test.

What happens during blood tests?

A blood test is usually quick and simple. You’ll be taken into a private room in a hospital or doctor’s surgery. A nurse will clean a patch of skin on your arm, insert a needle into a vein, and take a small amount of blood. You can read about the most common blood tests for heart health below:

Name

What it looks at

Used to help diagnose

Full Blood Count (FBC)

Red blood cells, white blood cells, platelets

Anaemia, infection, blood clotting

Urea, Electrolytes, Creatinine (UEC)

Blood glucose, calcium, potassium, magnesium

Diabetes, kidney problems, liver problems, dehydration

Liver Function Test (LFT)

 

Liver problems

Enzyme Tests

Troponin, Creatine Kinase (CK and CK-MB)

Heart attack, heart muscle damage

Lipid Profile

Cholesterol, LDL “bad” cholesterol, HDL “good” triglycerides

Risk for coronary artery disease

Blood Clotting

APTT, INR

Warfarin and Heparin levels

HbA1c

 

Diabetes risk (blood sugar level average over a 3-month period)

BNP

 

Heart failure and heart muscle damage

C-Reactive Protein

 

Inflammation

What happens after blood tests?

After your blood is collected, you’ll need to apply gentle pressure with a cotton ball and tape where the needle was inserted. This helps to prevent bruising or bleeding. Your blood sample will then be labelled and sent to a lab for testing. The test results will be sent to your doctor within a few days’ time, and your medical team will use the results to decide on the best treatment plan for you.

Sometimes your doctor may recommend a blood transfusion to replace blood lost through injury, disease or surgery. You receive the blood via a cannula inserted into your vein. To find out more about a blood transfusion, you can read the General Guide to Blood Transfusion - Information for Patients and Families.

 

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