OVERVIEW

What is pernicious anemia?

Pernicious anemia, also known as vitamin B₁₂ deficiency anemia, is a condition caused by insufficient red blood cell production due to a lack of vitamin B₁₂. This deficiency occurs because the stomach fails to produce enough intrinsic factor, a protein essential for vitamin B₁₂ absorption.

Common symptoms include fatigue, while other symptoms may involve depression, cognitive difficulties, numbness or tingling in the hands and feet, and balance problems.

Without proper treatment, some symptoms may become permanent. Pernicious anemia requires lifelong vitamin B₁₂ supplementation. If discontinued, vitamin B₁₂ levels may drop again, potentially leading to severe symptoms.

Is pernicious anemia common?

Pernicious anemia is relatively uncommon among Asians and typically affects older individuals, possibly due to age-related chronic atrophic gastritis in this population.

However, it can also develop before the age of 30 and may coexist with other autoimmune disorders, such as thyroid disease and vitiligo.

Is pernicious anemia the same as megaloblastic anemia?

No.

Pernicious anemia requires lifelong treatment and regular follow-ups with a hematologist. In contrast, most cases of megaloblastic anemia respond well to symptomatic treatment and do not necessitate lifelong medication.

Is pernicious anemia the same as cancer-related anemia?

No.

Pernicious anemia results from vitamin B₁₂ deficiency leading to insufficient red blood cell production. Cancer-related anemia, however, may arise from multiple causes, such as bone marrow suppression (reduced platelets in the blood), malabsorption, or malignancies (e.g., leukemia, lymphoma, and plasma cell disorders) that often affect the bone marrow's hematopoietic system.

SYMPTOMS

What are the common manifestations of pernicious anemia?

Mild pernicious anemia may have no symptoms. However, if vitamin B₁₂ levels drop low enough, patients may experience symptoms including:

• Pale skin or whitening of the mucous membranes on the inner side of the eyelids (visible by gently pulling down the lower eyelid to examine the conjunctiva), which should normally be light red.
• Feeling extremely fatigued.
• Rapid heartbeat.
• Shortness of breath.
• Headaches and muscle pain.
• Increased susceptibility to infections due to low white blood cell counts.
• Skin bruising or bleeding in certain areas due to low platelet counts.
• Changes in brain and nerve function may also occur, as vitamin B₁₂ is crucial for proper brain and nerve function. These changes may include: memory impairment and confusion; increased irritability or moodiness; tingling, burning, or numbness in the skin; weakness in the arms or legs; difficulty with balance.

What serious complications can pernicious anemia cause?

Severe consequences of pernicious anemia in the nervous system may include significant muscle weakness, spasticity, clonus, paraplegia, or even loss of bladder and bowel control. In the cardiovascular system, it can lead to heart failure, which is also one of the leading causes of death in patients with pernicious anemia.

CAUSES

What causes pernicious anemia?

The exact mechanism of pernicious anemia is not fully understood. Since patients often have idiopathic atrophic gastritis and intrinsic factor antibodies, it is considered an autoimmune disease. Its onset results from complex interactions between genetic and autoimmune factors.

Is pernicious anemia hereditary?

Pernicious anemia has some genetic association. The prevalence among family members of affected individuals is 20 times higher than in the general population.

Can pernicious anemia lead to stomach cancer?

Patients with pernicious anemia and chronic atrophic gastritis may have an increased risk of developing intestinal-type gastric cancer and gastric carcinoid tumors. However, the exact risk level varies depending on disease duration and geographic location.

DIAGNOSIS

How is pernicious anemia diagnosed?

The detection of intrinsic factor antibodies is highly valuable for diagnosing pernicious anemia, with a sensitivity of 50%–70% and a specificity close to 100%. Intrinsic factor is a crucial protein produced in the stomach for absorbing vitamin B₁₂.

For patients who test negative for intrinsic factor antibodies, additional tests may be required to aid in the diagnosis of pernicious anemia.
For example, elevated serum gastrin levels, low pepsinogen I levels, or a reduced ratio of pepsinogen I to pepsinogen II, while sensitive (90%–92%) for diagnosing pernicious anemia, lack specificity (meaning these results can also occur in other conditions).

Is a bone marrow examination necessary for pernicious anemia patients?

Bone marrow examination results are not specific for pernicious anemia and may not be required.

Which conditions can pernicious anemia be easily confused with?

Pernicious anemia can be confused with megaloblastic anemia caused by folate deficiency. Pernicious anemia results from vitamin B₁₂ deficiency, while folate deficiency-induced megaloblastic anemia is due to a lack of folate. These can be distinguished by measuring serum and red blood cell folate levels.

Pernicious anemia may also be confused with other causes of vitamin B₁₂ deficiency. Differentiation can be made by testing for intrinsic factor blocking antibodies and conducting a vitamin B₁₂ absorption test.

TREATMENT

Which department should I visit for pernicious anemia?

Hematology

Can pernicious anemia heal on its own?

Pernicious anemia requires active treatment, which should be lifelong. Without treatment, persistently low vitamin B₁₂ levels may lead to severe symptoms such as neurological abnormalities, slowed reactions, and unsteady gait.

How is pernicious anemia treated?

Pernicious anemia is treated by supplementing vitamin B₁₂.

Most patients receive parenteral (injected rather than oral) vitamin B₁₂ supplementation. The specific regimen involves daily vitamin B₁₂ injections for 1 week, followed by weekly injections for 4 weeks, and then monthly injections for life.

In some cases, based on clinical conditions and patient compliance, doctors may prescribe oral vitamin B₁₂ (controlled or sustained-release tablets are not suitable), which must also be taken lifelong.

Regardless of the treatment form, adherence to vitamin B₁₂ supplementation is crucial. Discontinuation may lead to a recurrence of low vitamin B₁₂ levels and severe symptoms.

Is long-term vitamin B₁₂ intake harmful for pernicious anemia patients?

Parenteral (non-oral) vitamin B₁₂ is inexpensive and relatively non-toxic (occasionally causing rash, itching, diarrhea, or allergic asthma). Excess amounts are excreted in urine without causing harm.

Can pernicious anemia be cured?

Pernicious anemia cannot be cured and must be managed as a chronic condition, similar to diabetes or hypertension, requiring lifelong treatment and regular medical follow-ups.

DIET & LIFESTYLE

Does pernicious anemia require follow-up examinations?

Pernicious anemia requires regular follow-up blood tests at the hematology clinic, with the specific frequency determined by the doctor.

Can people with pernicious anemia work and exercise normally?

With regular follow-up visits to the hematology clinic, pernicious anemia patients can generally work and exercise like normal individuals once their hemoglobin levels return to normal and there are no complications such as cardiopulmonary diseases affecting daily life.

PREVENTION

Can pernicious anemia be prevented? How to prevent it?

Pernicious anemia results from the interaction of genetic and autoimmune factors and cannot be prevented. Once diagnosed, active treatment should be pursued.

How can patients with pernicious anemia prevent complications?

Supplement with vitamin B₁₂ as prescribed by a doctor.