Pernicious anemia (PA)

Pernicious Anemia (PA)

Pernicious anemia (PA) is a type of vitamin B12 deficiency anemia caused by the body's inability to properly absorb vitamin B12, an essential nutrient required for the production of red blood cells and the proper functioning of the nervous system. The term "pernicious" refers to the severe, potentially life-threatening nature of the condition if left untreated.

Causes of Pernicious Anemia

Pernicious anemia is primarily caused by an autoimmune reaction that affects the stomach lining. Here are the main causes:

1. Autoimmune Attack on Parietal Cells:
   • The most common cause of pernicious anemia is the body’s immune system attacking the parietal cells in the stomach lining, which produce intrinsic factor (IF). Intrinsic factor is a protein essential for the absorption of vitamin B12 from the digestive tract.
2. Intrinsic Factor Deficiency:
   • Without intrinsic factor, vitamin B12 cannot be absorbed in the small intestine, even if it is present in food. This leads to B12 deficiency.
3. Genetic Factors:
   • There is a hereditary component to pernicious anemia. People with a family history of autoimmune disorders or pernicious anemia are at higher risk.
4. Other Causes:
   • Gastric surgery, such as gastric bypass or stomach resection, can reduce the stomach's ability to produce intrinsic factor.
   • Helicobacter pylori infection, which can damage the stomach lining.
   • Long-term use of certain medications such as proton pump inhibitors (PPIs) or H2 blockers can reduce stomach acid, interfering with B12 absorption.

Symptoms of Pernicious Anemia

Symptoms of pernicious anemia are often gradual and may worsen over time. Common symptoms include:

1. Fatigue:
   • Tiredness and weakness are the most common symptoms, resulting from the body’s inability to produce enough healthy red blood cells to carry oxygen efficiently.
2. Pale or Jaundiced Skin:
   • A lack of red blood cells can lead to paleness. In some cases, a yellowish tint to the skin and eyes (jaundice) may develop due to the breakdown of red blood cells.
3. Shortness of Breath:
   • Due to the low levels of red blood cells and hemoglobin, affected individuals may experience shortness of breath, particularly during physical exertion.
4. Numbness and Tingling:
   • Vitamin B12 deficiency can affect the nervous system, leading to neuropathy or damage to the nerves, causing sensations like numbness, tingling, or pins and needles, especially in the hands and feet.
5. Cognitive Issues:
   • Individuals may experience difficulty with memory, concentration, and confusion, sometimes leading to symptoms resembling dementia or cognitive impairment.
6. Glossitis and Mouth Ulcers:
   • A sore, inflamed, or swollen tongue (glossitis) and mouth ulcers can occur, along with a smooth appearance of the tongue.
7. Weakness in the Legs:
   • In some cases, people with pernicious anemia may experience weakness in the legs, making it difficult to walk or stand.
8. Heart Palpitations:
   • The heart may beat faster to compensate for the low oxygen levels in the blood, leading to palpitations.
9. Digestive Symptoms:
   • Some people may also experience nausea, vomiting, or diarrhea.

Diagnosis of Pernicious Anemia

Diagnosing pernicious anemia typically involves a combination of clinical evaluation and laboratory tests:

1. Blood Tests:
   • Complete blood count (CBC): A CBC will show signs of macrocytic anemia, where the red blood cells are larger than normal.
   • Vitamin B12 levels: Low levels of vitamin B12 in the blood are indicative of a deficiency.
   • Intrinsic factor antibodies: Blood tests may show the presence of antibodies against intrinsic factor or parietal cells, suggesting an autoimmune cause.
   • Methylmalonic acid (MMA) and homocysteine levels: Elevated levels of these compounds in the blood can indicate vitamin B12 deficiency.
2. Bone Marrow Biopsy:
   • In rare cases, a bone marrow biopsy may be done to rule out other causes of anemia.
3. Endoscopy:
   • An upper endoscopy might be performed to assess damage to the stomach lining and confirm the presence of atrophic gastritis, which is often associated with pernicious anemia.

Treatment of Pernicious Anemia

The treatment for pernicious anemia focuses on replacing vitamin B12 in the body. Since this condition is caused by an autoimmune deficiency in intrinsic factor, oral vitamin B12 supplementation is typically not effective. The treatment options include:

1. Vitamin B12 Injections:
   • The most common treatment is intramuscular vitamin B12 injections, which bypass the digestive system and are directly absorbed into the bloodstream.
   • Initially, patients may require frequent injections (often weekly or monthly) to replenish B12 stores and correct symptoms. Over time, the frequency may be reduced based on individual response.
2. Oral Vitamin B12 Supplements:
   • Some patients can take high doses of oral vitamin B12 supplements (often in the form of lozenges or sublingual tablets) as an alternative to injections, though this is less common for those with severe deficiencies.
3. Folic Acid and Iron Supplements:
   • In some cases, additional supplementation with folic acid and iron may be necessary, especially if there are concurrent deficiencies.
4. Treatment of Underlying Conditions:
   • If there is an underlying cause such as an H. pylori infection or gastric surgery, those conditions may also be treated to improve vitamin B12 absorption.

Prognosis of Pernicious Anemia

With prompt diagnosis and appropriate treatment, people with pernicious anemia can live normal lives. Vitamin B12 injections help manage the condition effectively, prevent further complications, and reverse many of the symptoms, particularly the blood-related issues. However, if left untreated, pernicious anemia can lead to serious complications such as:

• Neurological damage, including permanent nerve damage and cognitive decline.
• Heart issues, such as heart failure, due to long-term anemia.
• Gastric cancer may be a risk in individuals with longstanding pernicious anemia due to chronic atrophic gastritis.

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