Pernicious anaemia: what it is and how to test for it

When you hear the word “anaemia”, your mind might connect this to an iron deficiency. Pernicious anaemia is often misunderstood because the name sounds so similar, but it is its own medical condition.

Find out more about the condition, how to test, and how to treat.

We’ll cover:

• What is anaemia?
• Symptoms of anaemia
• What is pernicious anaemia?
• Symptoms of pernicious anaemia
• Who is at risk of pernicious anaemia?
• How to test for pernicious anaemia
• Treatment for pernicious anaemia

What is anaemia?
 

Firstly, let’s explain what anaemia means. Anaemia is a broad medical term for when your blood doesn’t have enough health red blood cells or haemoglobin (the protein that carries oxygen from your lungs to your body).

Common causes of anaemia include:

• Blood loss
• Lack of red blood cell production
• Increased red blood cell destruction

Symptoms of anaemia
 

There are a few different symptoms of anaemia as a result of your body’s lack of oxygen.

People with anaemia may experience:

• Extreme fatigue
• Weakness or lethargy
• Feeling faint or dizzy
• Breathlessness
• Pale skin

General anaemia is often related to nutritional deficiencies (such as iron, folate, or B12) and can sometimes be corrected with diet and supplements.

What is pernicious anaemia?
 

Pernicious anaemia is the most common cause of severe vitamin B12 deficiency in the UK [1,2].  Unlike common anaemia caused by dietary deficiency, pernicious anaemia is an autoimmune condition that affects how your body absorbs vitamin B12. In this condition, the immune system attacks the cells in the stomach that produce intrinsic factor (which combines with B12 and is necessary for absorption into the body).

Without enough intrinsic factors, the body can’t absorb vitamin B12 from the diet and can’t produce enough normal red blood cells – which then leads to anaemia. 

Without vitamin B12, several bodily processes are affected, including:

• Red blood cell production
• Nerve function
• DNA synthesis

You can read more about why vitamin B12 is important in our blog.

Symptoms of pernicious anaemia
 

The symptoms of pernicious anaemia are mainly linked to having a B12 deficiency, so there is a lot of overlap between the two. Symptoms vary from person to person.

You may experience:

• Mouth ulcers
• Pins and needles or numbness
• Sore, red tongue

Who is at risk of pernicious anaemia?
 

The exact cause of pernicious anaemia is unknown, but research shows it is more common in some people than others [4].

This includes:

• Women over age 60
• People with other autoimmune conditions
• Individuals with a family history of the condition

How can I test for pernicious anaemia?
 

It can take a long time to be diagnosed with pernicious anaemia, as the condition can progress slowly, and its symptoms are often confused with other conditions.

If left untreated, health issues may develop, such as [3]:

• Neurological problems such as memory or balance problems
• Nerve damage
• Digestive tract problems

So, it’s important to get tested if you suspect a B12 deficiency or have a family history of the condition.

You can ask your GP for a test, or if you want to test privately, you could start with a simple at-home Vitamin B12 Blood Test, or you can go one step further with a Pernicious Anaemia Blood Test.

This comprehensive panel includes:

• Full blood count – Assesses overall red blood cell health
• Active vitamin B12 – Detects true vitamin B12 deficiency
• Methylmalonic Acid (MMA) – Confirms functional B12 deficiency
• Intrinsic factor antibodies – Identifies autoimmune causes such as pernicious anaemia

This combination of markers is valuable, because a single B12 level alone might not accurately reflect deficiency or its cause.

How do you treat pernicious anaemia?
 

If you’re found to be deficient in vitamin B12 levels, your treatment will differ depending on the cause of your low levels. For example, if you don’t have enough B12 in your diet, then supplements may be recommended. 

However, if you have pernicious anaemia, you are likely to receive prescription B12 injections for life. 

It may feel overwhelming to be diagnosed with pernicious anaemia, but you are not alone. There is plenty of help and support around. 

The Pernicious Anaemia Society has information and resources on how to deal with your diagnosis, and member support groups to help you get in touch with other people going through the same experience. 

References

1. Signs and symptoms | Diagnosis | Anaemia - B12 and folate deficiency | CKS | NICE. [cited 29 Jun 2026]. 
2. Vitamin B12 or folate deficiency anaemia - Causes. In: nhs.uk [Internet]. 20 Oct 2017 [cited 29 Jun 2026].
3. Symptoms of Pernicious Anaemia | Pernicious Anaemia Society. In: https://pernicious-anaemia-society.org/ [Internet]. [cited 29 Jun 2026]. Available:
4. Vitamin B12 or folate deficiency anaemia - NHS. [cited 26 Jun 2026].