What is the treatment for Vitamin B12 (Cobalamin) deficiency?

From the Guidelines

Treatment of vitamin B12 deficiency should be initiated immediately, with hydroxocobalamin 1 mg intramuscularly administered on alternate days until there is no further improvement for patients with neurological involvement, and three times a week for 2 weeks for those without neurological involvement, followed by lifelong maintenance treatment with 1 mg intramuscularly every 2–3 months. This approach is based on the most recent guidelines from the British Obesity and Metabolic Surgery Society, as outlined in the 2020 update 1. The treatment regimen is crucial in preventing further complications, such as subacute combined degeneration of the spinal cord, which can occur if folic acid is given before addressing the vitamin B12 deficiency.

For patients with possible neurological involvement, such as unexplained sensory and/or motor and gait symptoms, urgent specialist advice should be sought from a neurologist and haematologist, in addition to initiating vitamin B12 treatment 1. The importance of prompt treatment and specialist consultation in these cases cannot be overstated, as it directly impacts morbidity, mortality, and quality of life.

Key points to consider in the treatment of vitamin B12 deficiency include:

• Immediate treatment with hydroxocobalamin for all patients with vitamin B12 deficiency, without first giving folic acid 1
• Differentiation in treatment approach based on the presence or absence of neurological involvement 1
• Lifelong maintenance therapy to prevent recurrence of deficiency and its complications 1
• Monitoring of treatment efficacy through clinical improvement and normalization of B12 levels, with attention to hematologic response 1

In clinical practice, adherence to these guidelines is essential for optimizing outcomes in patients with vitamin B12 deficiency, focusing on minimizing morbidity, reducing mortality, and improving quality of life 1.

From the FDA Drug Label

In patients with Addisonian Pernicious Anemia, parenteral therapy with vitamin B12 is the recommended method of treatment and will be required for the remainder of the patient’s life. Treatment of Vitamin B12 Deficiency Thirty mcg daily for 5 to 10 days followed by 100 to 200 mcg monthly injected intramuscularly.

The treatment of B12 deficiency with hydroxocobalamin (IM) involves:

• Parenteral therapy for patients with Addisonian Pernicious Anemia, which is required for the remainder of the patient's life.
• An initial dose of 30 mcg daily for 5 to 10 days, followed by 100 to 200 mcg monthly injected intramuscularly for other patients with vitamin B12 deficiency.
• Higher doses may be indicated for critically ill patients or those with neurologic disease, infectious disease, or hyperthyroidism.
• Oral therapy with a multivitamin preparation containing 15 mcg vitamin B12 daily may be suitable for patients with normal intestinal absorption 2.

From the Research

Treatment Options for B12 Deficiency

• Oral administration of high-dose vitamin B12 (1 to 2 mg daily) is as effective as intramuscular administration for correcting anemia and neurologic symptoms 3
• Intramuscular therapy leads to more rapid improvement and should be considered in patients with severe deficiency or severe neurologic symptoms 3
• A combination of methylcobalamin and adenosylcobalamin or hydroxocobalamin is recommended for treating vitamin B12 deficiency, as both forms have distinct metabolic fates and functions 4
• The oral route is comparable to the intramuscular route for rectifying vitamin B12 deficiency 4, 5

Dosage and Supplementation

• Daily doses of 647 to 1032 μg of cyanocobalamin were associated with 80% to 90% of the estimated maximum reduction in the plasma methylmalonic acid concentration 5
• Patients older than 50 years and vegans or strict vegetarians should consume foods fortified with vitamin B12 or take vitamin B12 supplements 3
• Patients who have had bariatric surgery should receive 1 mg of oral vitamin B12 per day indefinitely 3

Diagnosis and Testing

• Serum B12 is still the most commonly used and widely available test, but diagnostics by holotranscobalamin, serum methylmalonic acid, and plasma homocysteine measurements have grown in routine practice 6
• Measuring serum B12 alone is not sufficient for diagnosis; it is necessary to measure holotranscobalamin or functional markers of B12 adequacy such as methylmalonic acid or plasma total homocysteine 7

Prevention of Dementia and Stroke

• Metabolic vitamin B12 deficiency is common, being present in 10%-40% of the population, and contributes importantly to cognitive decline and stroke in older people 7
• B-vitamin therapy with cyanocobalamin reduces the risk of stroke in patients with normal renal function, but may be harmful in patients with renal impairment 7
• Methylcobalamin may be preferable in renal impairment, and future research is needed to distinguish the effects of thiocyanate from cyanocobalamin on hydrogen sulfide, and effects of treatment with methylcobalamin on cognitive function and stroke 7