Pernicious Anemia (Vit B12 Deficiency Anemia)

Pernicious Anemia (Vit B12 Deficiency Anemia)

Vitamin B12 (Vit B12)
 

Vitamin B12 is an essential nutrient that the body needs to make healthy red blood cells and to maintain a healthy functional nervous system.  It is found in animal foods, including meat, fish, eggs, milk, and other dairy products - but not in fruit or vegetables. Hence vegetarians have a high potential health risk towards this hematological disorder.

Normally, after a meal the body digestive enzymes will induce enzymatic breakdown of the food to release Vit B12 and allow its combination with an intrinsic factor in the stomach. The combined Vit B12-intrinsic factor complex is then absorbed into the body further down the gut at the end of the small intestine. (Intrinsic factor is produced by cells in the lining of the stomach and is essential for the absorption of Vit B12).

Background Information

Pernicious anemia is a type of anemia characterized by the body's inability to produce sufficient healthy RBCs due to the deficiency in Vit B12. In the circumstances of Vit B12 deficiency, RBCs are unable to divide normally resulting in large sized RBCs known as Macrocytes. Hence, structurally unable to squeeze out of the bone marrow into the blood stream. While, when they do squeeze through, most will develop an Ovalocytic morphology.

Theoretically, with insufficient functional healthy RBC to transport oxygen throughout the body, one will feel lethargic. Severe or prolonged pernicious anemia can damage the heart, brain, and other organs in the body. Additionally, nerve damage, neurological problems (such as memory loss), and digestive tract problems may occur too. Patients who suffer pernicious anemia also may be at higher risk for weakened bone strength and stomach cancer.

Causes of Pernicious Anemia

1. Autoimmunity  

In a regulated manner, a host's immune system normally produces antibodies to attack bacteria, viruses and other germs. A patient suffering from autoimmune disease, infers that the immune system is producing antibodies against specific host's own body cells - self-antibodies. In the case of pernicious anaemia, self-antibodies are either specifically produced against the host intrinsic factor or against the cells in the stomach that synthesize intrinsic factor. This then prevent the downstream absorption processes of Vit B12. Unfortunately, in most cases the trigger of this condition is idiopathic.

Pernicious anaemia usually develops over the age of 50. Women are more commonly affected than men, and it tends to run in families. It occurs more commonly in people who have other autoimmune diseases. For example, thyroid diseases, Addison's disease and vitiligo (a condition where white patches develop on skin). Fortunately, there are diagnostic tests to confirm the presence of such antibodies which cause pernicious anaemia.

2. Stomach or gut problems  

Patients who had undergone surgery to remove the stomach or the end of the small intestines will mean absorption of vitamin B12 may be disrupted

Some diseases like Crohn's disease affect the end of the small intestines where Vit B12 is absorbed and thus disrupts its absorption.

There are some clinical disorders such as atrophic gastritis (thining of the lining of the stomach) that may disrupt the synthesis and/or secretion of intrinsic factor leading to malabsorption of the vitamin .

3. Side-effects of Medication

Certain medicines used for other conditions may disrupt the absorption of vitamin B12. The most common example is metformin which is a medicine often used for diabetes. Other medicines include colchicine, neomycin, and some anticonvulsants used to treat epilepsy.

Long-term use of medicines that disrupts stomach acid synthesis and/or secretion, such as H2 blockers and proton pump inhibitors, can deteriorate the Vit B12 deficiency condition. This is because stomach acid is needed to release Vit B12 bound to proteins in food. However, they are not considered critical root causes of vitamin B12 deficiency.

4. Dietary Deficiency

In this modern society and the wealth of food sources, it is unusual to suffer from dietary  Vit B12 deficiency under a normal balanced diet regime. Though, strict vegans on the other hand who consume no animal or dairy produce may suffer from vitamin B12 deficiency. 

 

Diagnosis

• Low hemoglobin level 
• Evaluated MCV
• Elevated/normal MCHC
• Ovalocytes are observed on the PBF
• Hypersegmented neutrophils are observed on the PBF.