Standard Treatment for Low Vitamin B12

Diagnosis and Treatment

The standard treatment for patients with vitamin B12 deficiency is 1000 mcg of vitamin B12 administered intramuscularly every other day for one week, followed by monthly injections for life, though high-dose oral supplementation (1000-2000 mcg daily) may be effective in many cases, according to Clinical Nutrition guidelines 1
Diagnosis is based on low serum cobalamin levels along with functional biomarkers such as elevated homocysteine or methylmalonic acid, with clinical B12 deficiency further requiring macrocytosis and/or neurological symptoms 2
For patients with Crohn's disease and ileal resection, 1000 mg of vitamin B12 prophylactically every month indefinitely is recommended when more than 20 cm of distal ileum is resected 1
Patients with more than 30 cm of distal ileum resected are at higher risk and should be monitored more closely 2, 1
Patients on certain medications, such as sulphasalazine and methotrexate, should also receive vitamin B9/folic acid supplementation 1
CD patients with ileal involvement and/or resection should be screened yearly for vitamin B12 deficiency 2, 1