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Pernicious anemia is one of blood disorder that develop mainly due to vitamin B12 deficiency which an essential vitamin for red blood cells development. In this article we will explore the causes, symptoms, diagnosis and treatments.
Content :
Pernicious anemia (PA) is a relatively rare autoimmune disease characterized by chronic atrophic gastritis that prevents the body from absorbing vitamin B12 (cobalamin) which leads to vitamin B12 deficiency.
This deficiency results in a decreased number of blood cells capable of carrying an adequate amount of oxygen, potentially causing megaloblastic anemia.
The presentation of pernicious anemia can range from subtle symptoms to a wide array of manifestations, further complicated by a lack of accurate diagnostic tests, making diagnosis challenging.
Treatment typically involves lifelong vitamin B12 supplementation, often administered through injections as the body has difficulty absorbing this viramin.
Maintaining a normal level of cobalamin requires not only an adequate intake of vitamin B12 from sources such as eggs, meat, and dairy products but also satisfactory absorption of this vitamin. This absorption is facilitated by three main proteins: haptocorrin, intrinsic factor (IF), and transcobalamin.
In cases of pernicious anemia, vitamin B12 deficiency arises generally from the autoimmune destruction of parietal cells in the stomach which are responsible for the production of intrinsic factor. This destruction is mediated by the presence of autoantibodies, specifically intrinsic factor autoantibodies (IFA) and parietal cell autoantibodies (PCA).
The role of this factor is to bind to vitamin B12 and facilitate its transport to the terminal ileum. Once there, it binds to its carrier, transcobalamin, which is then released into the bloodstream. It subsequently reaches cellular receptors where vitamin B12 undergoes transformations, converting into methylmalonic acid (MMA) and adenosylmethionine (SAM).
Pernicious anemia is described as a slowly progressive disease that needs 2-5 years to become apparent clinically. Symptoms of anemia may not be apparent until anemia become relatively profound that's because cardiopulmonary mechanisms facilitate increased oxygen delivery to overcome symptoms of anemia.
Pernicious anemia can effect on many organs as patient may present with neurological, cardiac and gastrointestinal symptoms.
1- Constitutional symptoms (symptoms of anemia): fatigue, lethargy, anorexia, paleness and cold extremities and weight loss.
2- Neurological symptoms: all symptoms occur due to demyelination of nerves because of vitamin B12 deficiency:
3- Neuropsychiatric Disorders: Mood disorders such as depression, mania, chronic fatigue syndrome, and psychosis.
4- Gastrointestinal Symptoms: Dyspepsia, epigastric pain, early satiety, and postprandial bloating (fullness).
5- Symptoms of Other Autoimmune Disorders.
Initial diagnosis involves obtaining a thorough medical history from the patient, followed by general investigations to rule out other types of anemia.
In pernicious anemia, symptoms can vary from one case to another, necessitating reliance on clinical examination and further investigations for an accurate diagnosis by the physician.
1- Complete Blood Count (CBC):
2- Reticulocyte count may be reduced.
3- Isolated Serum Cobalamin Levels:
4- Measuring Methylmalonic Acid (MMA) and Homocysteine:
5- Folate Levels:
6- Serological Tests:
7- Serum Bilirubin Level.
8- Lactate Dehydrogenase (LDH) Levels: Highly elevated in pernicious anemia.
9- Peripheral Blood Smear:
Gastric endoscopic examination is performed to detect the presence of atrophic gastritis, an inflammation of the stomach that can lead to a decrease in intrinsic-producing cells. Biopsies may also be taken during this examination.
Once pernicious anemia is diagnosed, prompt treatment is crucial due to its chronic nature and potential for life-threatening complications. The primary goal of treatment is to raise vitamin B12 levels and manage pernicious anemia symptoms.
1- Initiation of Treatment:
2- Maintenance Treatment:
In conclusion, patients with pernicious anemia may exhibit a range of hematological, neurological, psychological, or gastroenterological symptoms. Diagnosis involves laboratory and immunological tests. Being a chronic condition, the primary treatment revolves around vitamin B12 replacement therapy
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