Vitamin B12 Test

The Vitamin B12 test is a blood test used to measure the level of vitamin B12 in the blood. Vitamin B12 is an essential nutrient that plays a crucial role in the production of red blood cells, nerve function, and DNA synthesis.

Why is the test performed?

The Vitamin B12 test is performed to:

• Diagnose vitamin B12 deficiency or deficiency anemia
• Monitor the effectiveness of treatment for vitamin B12 deficiency
• Investigate the cause of certain symptoms such as fatigue, weakness, and numbness or tingling in the hands and feet
• Screen for vitamin B12 deficiency in individuals with a history of gastrointestinal disorders, such as celiac disease or Crohn's disease
• Monitor vitamin B12 levels in individuals taking medications that interfere with vitamin B12 absorption, such as proton pump inhibitors

How is the test performed?

The Vitamin B12 test is a simple blood test that involves:

• A healthcare professional drawing a blood sample from a vein in the arm
• The blood sample being sent to a laboratory for analysis
• The laboratory measuring the level of vitamin B12 in the blood using a technique called radioimmunoassay or chemiluminescent immunoassay

What are the normal ranges for vitamin B12 levels?

The normal range for vitamin B12 levels varies depending on the laboratory and the individual's age, but generally falls within the following ranges:

• Adults: 200-900 pg/mL
• Pregnant women: 150-700 pg/mL
• Children: 100-500 pg/mL
• Infants: 50-200 pg/mL

What do abnormal results mean?

Abnormal results may indicate:

• Vitamin B12 deficiency: levels below 200 pg/mL
• Mild vitamin B12 deficiency: levels between 150-200 pg/mL
• Severe vitamin B12 deficiency: levels below 100 pg/mL
• Vitamin B12 excess: levels above 900 pg/mL (rarely seen)

What are the risks and limitations of the test?

The Vitamin B12 test is a relatively safe and simple procedure, but as with any blood test, there may be some risks and limitations, including:

• Bleeding or bruising at the needle site
• Infection at the needle site
• Fainting or dizziness due to the sight of blood or the needle
• False-negative results if the test is performed too early in the course of vitamin B12 deficiency
• False-positive results if the test is affected by certain medications or medical conditions

What are the next steps after an abnormal result?

If an abnormal result is obtained, the healthcare professional may:

• Repeat the test to confirm the result
• Perform additional tests to investigate the cause of the vitamin B12 deficiency, such as a complete blood count or a gastrointestinal evaluation
• Prescribe vitamin B12 supplements or injections to treat the deficiency
• Refer the individual to a specialist, such as a hematologist or gastroenterologist, for further evaluation and treatment