What is the treatment for vitamin B12 deficiency in a 17-year-old?

Treatment of Vitamin B12 Deficiency in a 17-Year-Old

For vitamin B12 deficiency in a 17-year-old, the recommended treatment is hydroxocobalamin 1 mg intramuscularly three times a week for 2 weeks, followed by maintenance treatment with 1 mg intramuscularly every 2-3 months for life. 1

Initial Treatment Protocol

• For patients without neurological involvement, administer hydroxocobalamin 1 mg intramuscularly three times a week for 2 weeks 1
• For patients with neurological involvement (such as cognitive difficulties, balance issues, pins and needles), administer hydroxocobalamin 1 mg intramuscularly on alternate days until there is no further improvement 1, 2
• After initial treatment, transition to maintenance therapy with hydroxocobalamin 1 mg intramuscularly every 2-3 months for life 1, 2

Treatment Based on Cause of Deficiency

• Determine the underlying cause of B12 deficiency in the adolescent, which could include: 3

  • Diet low in vitamin B12 (vegan/vegetarian diet) 3
  • Malabsorption issues 1
  • Medication effects (metformin, H2 blockers, etc.) 3
  • Autoimmune conditions (such as pernicious anemia) 4
  • In rare cases, excessive alcohol consumption 5

• For deficiency due to malabsorption, parenteral vitamin B12 will be required for life 1, 4

• For dietary deficiency without malabsorption, oral supplementation may be considered after initial parenteral treatment 6

Dosage Considerations

• While the FDA label for cyanocobalamin indicates 100 mcg dosing 4, more recent guidelines recommend higher doses of 1000 mcg (1 mg) for better retention 1, 7
• Hydroxocobalamin is preferred over cyanocobalamin, especially in patients with renal dysfunction 2
• Never administer folic acid before treating vitamin B12 deficiency, as it may mask underlying B12 deficiency and precipitate subacute combined degeneration of the spinal cord 1, 4

Monitoring and Follow-up

• Monitor hematologic response with hematocrit and reticulocyte counts daily from the fifth to seventh days of therapy 4
• Continue monitoring until hematocrit normalizes 4
• Check both vitamin B12 and folate levels, as folate deficiency may coexist 1
• Consider measuring methylmalonic acid as a confirmatory test when initial B12 results are indeterminate 1, 6

Special Considerations for Adolescents

• Ensure adequate intake of vitamin B12 (0.5 to 3 mcg daily) as recommended by the Food and Nutrition Board 4
• For adolescents with dietary restrictions (vegans/vegetarians), emphasize the importance of vitamin B12 supplementation 4, 6
• In cases where B12 deficiency is related to alcohol consumption in adolescents, addressing the underlying alcohol use is essential 5
• Oral administration of high-dose vitamin B12 (1-2 mg daily) can be considered as an alternative to intramuscular administration, particularly for maintenance therapy or in cases with good intestinal absorption 6, 5, 8

Important Precautions

• Vitamin B12 deficiency left untreated for longer than 3 months may produce permanent degenerative lesions of the spinal cord 4
• Doses of folic acid greater than 0.1 mg per day may result in hematologic remission in patients with vitamin B12 deficiency but will not prevent neurologic manifestations 4
• If reticulocytes have not increased after treatment or if reticulocyte counts do not continue at least twice normal as long as the hematocrit is less than 35%, diagnosis or treatment should be reevaluated 4