This is a simple test to show if Vitamin B12 is being absorbed properly.

Vitamin B12 is normally absorbed in the ileum. If this has been damaged by severe Crohn's disease or removed at surgery, B12 levels in the body will eventually become depleted. This may lead to anaemia and damage to nerves.

Vitamin B12 can be found in meat and dairy products and is stored in large quantities in the liver. It can take up to 3-5 years for the body's stores to become deficient if malabsorption occurs.

Preparation for the test
You must eat or drink nothing after midnight.

Description of the test
Two capsules containing a small amount of radioactivity are swallowed, followed by an injection of non-radioactive vitamin B12 into the muscle.

No further solid food is taken over the next two hours but fluids are allowed.

All urine is collected over the next twenty-four hours and returned to the Department of Nuclear Medicine.

After the test
The urine will be analysed for the amount of radioactive material present and the results will be sent to your doctor. If the results show that vitamin B12 absorption is insufficient, you may need to have the body's stores maintained by injection. These are usually given every three months.