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Vitamin B12 test

2-minute read

You need vitamin B12 in your blood so you can make blood cells and have your nerves function well. Vitamin B12 is also known as cobalamin.

What is being tested?

This test measures the amount of vitamin B12 in your blood. Folate is usually tested at the same time.

Vitamin B12 come from food such as meat, poultry, seafood, milk, cheese and eggs.

Vitamin B12 is vital for making red blood cells and for cell and tissue repair. Vitamin B12 is also needed for nerve health.

Why would I need this test?

Your doctor might request this test:

  • to help assess anaemia (lack of red blood cells)
  • as part of a pre-pregnancy health check
  • to help assess nerve health
  • to help check your nutritional status, especially if you are a vegan
  • to help diagnose the cause of changes in your mental state or behaviour

How to prepare for this test

You will need to fast for 6 – 8 hours before your blood sample is taken.

Understanding your results

A lower than normal level of vitamin B12 means your body lacks the vitamin. However, the result does not provide information what is causing the deficiency, or the severity of that condition.

Vitamin B12 deficiency can be caused by a wide range of conditions. It can also be caused by a vegetarian or vegan diet. You need to discuss your results with your doctor to fully understand what the results mean for you.

More information

About vitamin B12 testing

Lab Tests Online has more information about vitamin B12 testing.

About blood testing

Visit healthdirect's 'Guide to blood testing' to learn more about blood tests in general, including information about:

  • what to consider before having the test
  • what happens during a blood test
  • results accuracy
  • blood tests cost

Learn more here about the development and quality assurance of healthdirect content.

Last reviewed: August 2018

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