Overview of pernicious anaemia 

Pernicious anaemia is an autoimmune condition in which there is a decrease in red blood cells because the intestines cannot properly absorb vitamin B12. There are many alternative names: Macrocytic achylic anaemia, congenital pernicious anaemia, Juvenile pernicious anaemia, Vitamin B12 deficiency (malabsorption) anaemia, Biermer anaemia, and Addison anaemia. It affects all ages, but is most commonly seen among women aged 60 years and older.

In this article, we will discuss pernicious anaemia, its causes, and treatment. Furthermore, the article will elaborate on vitamin B12 deficiency, its symptoms, recommended dosage, and treatment, emphasising the importance of a vitamin B12-rich diet, which is essential for pernicious anaemia.

Importance of vitamin B12 in the body

The initial mechanism in pernicious anaemia is to reduce dietary B12 absorption. Vitamin B12 is important for erythropoiesis and nerve myelination. Its deficiency leads to megaloblastic anaemia due to disruption in DNA synthesis and demyelinated nerves.^{1 5}

Understanding pernicious anaemia  and vitamin B12 deficiency

Pernicious anaemia is one of the causes of Vitamin B12 deficiency, which prevents the absorption of Vitamin B12. If there is insufficient vitamin B12, there are very few blood cells carrying oxygen to the entire body. It takes many years to develop noticeable changes in our bodies. If we do not treat it, then it will cause serious medical effects, damaging our nervous system.²

A lack of intrinsic factor leads to poor absorption of Vitamin B12 from food in pernicious anaemia.

Symptoms 

Early symptoms are not identifiable, as compensatory mechanisms from both the heart and lungs increase oxygen delivery. Since the condition is progressing very gradually, it will be necessary to conduct appropriate clinical testing to make an early diagnosis. Since the symptoms are always present in other conditions, there is a delay in diagnosis.

• Constitutional: fatigue, loss of weight, not feeling hungry, loss of weight
• Neurological: Headache, confusion, difficulty concentrating, loss of memory, paresthesia, numbness, loss of balance, cognitive decline
• Psychiatric: emotional liability, changes in personality, feeling depressed, psychosis
• Cardiopulmonary: palpitations, difficulty breathing
• Otolaryngologic: Hypogeusia/ageusia, glossitis (inflammation of the tongue)
• Gastrointestinal: dyspepsia, diarrhoea, decreased appetite

Evaluation

Diagnosis will include a combination of the following tests when evaluating for pernicious anaemia.

1. Initial serology: Complete blood count (CBC), serum cobalamin (vitamin B12), folate, and an iron panel, which includes serum iron, total iron-binding capacity (TIBC), and ferritin, along with a reticulocyte count
2. Peripheral blood smear
3. Further serological tests: Anti-intrinsic factor (anti-IF) antibodies and anti-parietal cell antibodies
4. Additional biochemical markers: Methylmalonic acid (MMA), fasting homocysteine, and holotranscobalamin (holoTC)
5. Bone marrow biopsy (if diagnosis remains unclear or in suspected haematological malignancy)
6. Endoscopy with biopsy: To evaluate for gastric atrophy or other GI pathology (e.g. in suspected pernicious anaemia or malabsorption)

Treatment/management

Patients who are confirmed with pernicious anaemia start with an IM injection of 1000 micrograms of B12 (cyanocobalamin in the United States and hydroxocobalamin in Europe). It is administered every day for 1 to 2 weeks, it is followed by weekly injections for 1 to 2 months.

Later, a monthly injection every 2 to 3 months.

Once the intensive treatment phase is done, patients can continue IM injections, or they can have alternative treatment with a high dose of oral vitamin B12 for the lifelong maintenance phase.¹   

Diet cannot fully replace the need for B12 injections or supplements due to absorption issues in pernicious anaemia. But a rich vitamin B12 diet supports our complete health and is good for better health.

Role of vitamin B12 in the body

Vitamin B12 or cobalamin deficiency anaemia 

Vitamin B12 deficiency anaemia, also known as cobalamin deficiency anaemia, is a condition in which our body does not make healthy red blood cells.

Our body needs vitamin B12 to make healthy red blood cells (RBC), white blood cells (WBC), and platelets. When our body does not make vitamin B12, we have to get it from the foods we eat or from supplements.³

When we cannot absorb Vitamin B12 due to gut problems in pernicious anaemia, it will lead to defects in red blood cell production and lead to anaemia.

Elderly individuals, vegans, vegetarians, and those with gastrointestinal surgeries or disorders are also in need of vitamin B12.

Symptoms of vitamin B12 anaemia 

Symptoms of Vitamin B12 anaemia are similar to those of anaemia, such as fatigue, paleness, shortness of breath, headache, or feeling dizzy. If the case is left untreated, they may experience symptoms affecting the brain and nervous system.

Symptoms include:

• Tingling feeling or pain
• Trouble  walking
• No control over muscle movements
• Prone to confusion, slow thinking capacity, and forgetfulness
• Mood changes and mental instability, including depression or irritability
• Problems with smell, taste, and prone to vision defects
• Diarrhoea and weight loss
• Red and painful tongue

Causes of vitamin B12 deficiency anaemia 

1. The main reason is that there is a deficit of the intrinsic factor in pernicious anaemia 
2. Alcohol consumption decreases the body's ability to absorb vitamin B12 
3. When certain medicines are taken, it becomes harder for the body to absorb Vitamin B12. Metformin and some heartburn medicines are a few examples
4. Some Medical conditions can raise the risk:
   • Celiac disease, type 1 diabetes, and thyroid disease increase the risk of B12 deficiency  
   • Chronic pancreatic disease
   • Genetic conditions like inherited intrinsic factor deficiency, 
   • Imerslund-Grasbeck syndrome and inherited transcobalamin deficiency.
   • Intestinal and digestive conditions like ulcerative colitis, Crohn's disease, and  Helicobacter pylori infection 
   • Vitiligo
   • Stomach surgery - when surgical procedures are undergone, like weight loss surgery or gastrectomy, it is harder for the body to absorb Vitamin B12

Vitamin B12 - requirement per day

Recommended daily amounts of vitamin B12, in micrograms(mcg).⁷

Healthy and abnormal haemoglobin and vitamin B12 blood levels in adults.⁷

Treatment of vitamin B12 anaemia 

Treatment depends on the extent of the condition. Vitamin B12 medications can be taken orally, as a nasal spray, or as an injection, which increases the levels in the bloodstream. Vitamin B12 shots will be recommended until healthy levels are reached. Blood transfusion in combination with Vitamin B12  is one of the treatments in critical cases.

Vitamin B12-rich food is recommended in an everyday diet. Some symptoms might take months to improve, and some might persist even after the treatment.

Dietary sources of vitamin B12

Food

Vitamin B12 is present in foods of animal origin, which include fish, meat, poultry, eggs, and dairy products. 

Plant foods do not contain vitamin B12 naturally. Cereals and nutritional yeasts are great sources of vitamin B12. Their bioavailability is higher compared to (should check the nutritional value of the label, it would mention the percentage of B12 added).  

The US Food and Drug Administration states that the infant formula sold in the US should have at least 0.15 mcg of Vitamin B12 per 100 kcal

The bioavailability of Vitamin B12  from food changes depending on the vitamin B12 dose, since absorption reduces when the intrinsic factor is high.

Bioavailability varies with all types of food. Milk products are higher in bioavailability than meat sources.

There is always a 50 per cent increased bioavailability of vitamin B12 from supplements than to other sources.⁴

Food sources factsheet.⁶                                                           

FAQs

What are the types of anaemia?

Iron deficiency anaemia, Vitamin B12 deficiency anaemia, Aplastic anaemia, Hemolytic anaemia 

What are the anaemias that are closely related to Vitamin B12 deficiency?

Megaloblastic anaemia, Pernicious anaemia, folate deficiency anaemia. 

Are there any facial signs of B12 deficiency?

Hyperpigmentation, Vitiligo, angular stomatitis, hair and nail changes.

What is vitiligo?

 Vitiligo is a chronic condition where white patches develop on the skin. The main cause is reduced melanin pigmentation.

Does vitamin B12 therapy reduce cutaneous lesions?

Yes, vitamin B12 treatment has reduced cutaneous lesions.

Summary

All in all, pernicious anaemia is an autoimmune condition that leads to vitamin B12 deficiency. It might be due to a lack of intrinsic factor, autoimmune gastritis, or other autoimmune conditions. Vitamin B12 plays an important role in the formation of RBCs, WBCs, and platelets. When there is a deficiency of B12, people undergo multiple symptoms. It's recommended to get an evaluation and take proper treatment accordingly.

People affected with pernicious anaemia must take B12 injections or supplements. Also, a Vitamin B12-rich nutrient diet plays a major role in maintaining good health. Therefore, it is important to consume B12-rich food regularly in one's diet. It's also essential to check, monitor the levels, and take adequate supplements as required.