From the Guidelines
The initial workup for suspected pernicious anemia should include a complete blood count, serum vitamin B12 levels, methylmalonic acid and homocysteine levels, and testing for anti-intrinsic factor and anti-parietal cell antibodies to confirm the autoimmune etiology, and treatment consists of vitamin B12 replacement, typically starting with intramuscular hydroxocobalamin injections at 1 mg three times a week for 2 weeks, followed by maintenance treatment with 1 mg intramuscularly every 2–3 months for life, as recommended by the British Obesity and Metabolic Surgery Society guidelines 1.
Initial Workup
The initial workup for suspected pernicious anemia includes:
- A complete blood count to identify macrocytic anemia
- Serum vitamin B12 levels
- Methylmalonic acid and homocysteine levels, which are elevated in B12 deficiency
- Testing for anti-intrinsic factor and anti-parietal cell antibodies to confirm the autoimmune etiology
Treatment
Treatment consists of vitamin B12 replacement, typically starting with:
- Intramuscular hydroxocobalamin injections at 1 mg three times a week for 2 weeks, as recommended by the British Obesity and Metabolic Surgery Society guidelines 1
- Maintenance treatment with 1 mg intramuscularly every 2–3 months for life For people with neurological involvement, hydroxocobalamin 1 mg intramuscularly should be administered on alternate days until there is no further improvement, then hydroxocobalamin 1 mg intramuscularly administered every 2 months, and urgent specialist advice from a neurologist and haematologist should be sought 1.
Monitoring and Follow-up
Patients should be monitored for clinical improvement, with:
- Reticulocytosis typically occurring within days
- Hemoglobin levels normalizing within 1-2 months
- Neurological symptoms may take longer to resolve, and some deficits may be permanent if treatment is delayed Concurrent folate levels should be checked and supplemented if necessary, as folate deficiency can mask B12 deficiency symptoms while neurological damage progresses, and folic acid deficiency may indicate non-adherence with the daily multivitamin and mineral supplement or malabsorption, and treatment of folic acid deficiency should be given after excluding vitamin B12 deficiency, with oral folic acid 5 mg daily for a minimum of 4 months 1.
From the FDA Drug Label
Pernicious Anemia Parenteral vitamin B12 is the recommended treatment and will be required for the remainder of the patient's life. A dose of 100 mcg daily for 6 or 7 days should be administered by intramuscular or deep subcutaneous injection. If there is clinical improvement and if a reticulocyte response is observed, the same amount may be given on alternate days for seven doses, then every 3 to 4 days for another 2 to 3 weeks. By this time hematologic values should have become normal This regimen should be followed by 100 mcg monthly for life. Folic acid should be administered concomitantly if needed.
The initial workup for pernicious anemia is not explicitly stated in the label, but the initial treatment involves:
- Administering 100 mcg of vitamin B12 daily for 6 or 7 days via intramuscular or deep subcutaneous injection
- Following this with 100 mcg on alternate days for seven doses, then every 3 to 4 days for another 2 to 3 weeks
- Eventually switching to a monthly dose of 100 mcg for life
- Concomitant administration of folic acid if needed 2
From the Research
Initial Workup for Pernicious Anemia
The initial workup for pernicious anemia typically involves a combination of laboratory tests and physical examinations to confirm the diagnosis. Some key components of the initial workup include:
- Full blood count (FBC) to check for anemia and other blood cell abnormalities 3
- Serum vitamin B12 levels to check for deficiency, although it's important to note that false normal levels can occur due to interference from intrinsic factor antibodies 4, 5
- Homocysteine and methylmalonic acid levels to check for signs of cobalamin deficiency 4
- Anti-intrinsic factor antibodies and anti-parietal cell antibodies to check for autoimmune chronic atrophic gastritis 3, 6
- Bone marrow biopsy to check for trilineage dysplasia and other abnormalities 5
Treatment of Pernicious Anemia
The treatment of pernicious anemia typically involves vitamin B12 replacement therapy. Some key points to consider include:
- Oral vitamin B12 replacement therapy can be effective, even in patients with pernicious anemia, although parenteral treatment may be necessary in some cases 6
- Iron deficiency is common in patients with pernicious anemia, and iron supplementation may be necessary 7
- Intravenous iron supplementation may be more effective than oral supplementation in some cases 7
- Regular assessment of iron status and vitamin B12 levels is important to monitor the effectiveness of treatment and adjust as needed 7