Pernicious anemia is a disease caused by a deficiency of vitamin B12 due to the body's inability to absorb it properly. This is primarily because of a lack of intrinsic factor, a protein produced by the stomach that is necessary for vitamin B12 absorption in the small intestine. The condition is most commonly caused by an autoimmune attack on the stomach cells that produce intrinsic factor. Symptoms include fatigue, weakness, shortness of breath, pale skin, numbness or tingling in hands and feet, difficulty walking, memory problems, and a smooth red tongue. If untreated, some symptoms can become permanent. Treatment typically involves lifelong vitamin B12 injections or supplements to restore and maintain vitamin B12 levels. Pernicious anemia is more common in older adults, especially those of northern European descent, and is associated with an increased risk of stomach cancer that requires regular monitoring.
Causes and Pathophysiology
- It is an autoimmune disorder in which the immune system attacks the stomach cells producing intrinsic factor.
- Intrinsic factor deficiency leads to impaired absorption of vitamin B12, causing megaloblastic anemia.
- Vitamin B12 deficiency disrupts DNA synthesis and nerve function due to its essential role as a cofactor in enzymatic reactions.
Symptoms
- Fatigue, weakness, pale skin, shortness of breath, chest pain.
- Neurological symptoms like numbness, poor reflexes, memory loss, clumsiness.
- Gastrointestinal symptoms including loss of appetite, nausea.
- Psychiatric symptoms such as depression or confusion may also appear.
Diagnosis and Treatment
- Diagnosed by blood tests showing low vitamin B12, large red blood cells, and antibodies against intrinsic factor.
- Treatment requires lifelong vitamin B12 injections to compensate for absorption failure.
- Oral supplements may be less effective, especially initially.
Risk Factors and Epidemiology
- More common over age 60 and in people of northern European descent.
- Females are more affected than males.
- Often associated with other autoimmune diseases such as type 1 diabetes and thyroid disorders.
This comprehensive summary reflects the current understanding of pernicious anemia.
