About the test

A Vitamin B12 test checks the level of vitamin B12 in your blood. This essential nutrient supports red blood cell production, nerve health, and DNA synthesis. Low levels can lead to fatigue, memory issues, or anaemia. The test is quick, simple, and can help you stay on top of your health.

Why it’s done

You might need a Vitamin B12 test if you have:

• Symptoms of B12 deficiency like persistent tiredness, pale skin, or tingling in hands and feet
• Macrocytic anaemia, where red blood cells are larger than normal
• Digestive conditions such as Crohn’s disease or coeliac disease
• A vegan or vegetarian diet, which may lack natural B12 sources
• Neurological symptoms like memory loss or mood changes
• Increased needs during pregnancy
• A history of gastrointestinal surgery or chronic medication use that affects absorption
• A sore, red tongue and mouth ulcers are sometimes noted
• Shortness of breath

What to expect

A small blood sample is taken, usually from your arm. The test is quick and typically takes just a few minutes at your nearest Western Diagnostic Pathology collection centre.

How to prepare

No special preparation is usually needed. However, let your doctor know about any supplements or medications you’re taking, as they may affect results.

What results mean

• Low B12: May suggest deficiency, often linked to diet, absorption issues, or chronic illness
• Borderline levels: May require further testing (e.g. holotranscobalamin or methylmalonic acid)
• High B12: Rare, but can occur with liver disease or supplementation

Common conditions linked to low B12 include:

• Pernicious anaemia
• Malabsorption syndromes
• Long-term use of certain medications (e.g. metformin, PPIs)

When to speak to your doctor

Talk to your GP if you notice:

• Ongoing fatigue or weakness
• Tingling or numbness in your hands or feet
• Memory issues or mood changes
• You follow a plant-based diet or have had gut surgery

Early detection can prevent long-term nerve damage.

Related tests

• Folate test – often done alongside B12
• Full blood count (FBC) – checks for anaemia
• Holotranscobalamin – measures active B12
• Methylmalonic acid – used when B12 levels are borderline

Unique clinical insight

Vitamin B12 deficiency can mimic dementia symptoms in older adults — but it’s reversible with early treatment.

Patient scenario

Maria, 42, a vegetarian from Victoria, felt constantly tired. Her GP ordered a Vitamin B12 test through Dorevitch Pathology. Results showed low B12, and with supplements, her energy returned within weeks.