Constitutional Megaloblastic Anemia Due To Vitamin B12 Metabolism Disorder C5681709
A rare blood disorder where the body cannot properly use vitamin B12 to make red blood cells. This causes anemia with fatigue and weakness. Lifelong B12 supplementation is usually necessary.
Key facts at a glance
- ICD-10
- D64.9
- ICD-11
- 3A00.0
- Body system
- hematologic
- Severity
- moderate
- Chronic
- true
Signs and symptoms
Common signs and symptoms that may indicate this condition.
Fatigue
(hematologic)Generalized symptoms
(hematologic)Noticeable symptoms that may vary in intensity over time.
Frequency: Common at all stages
Pallor
(hematologic)Glossitis
(hematologic)Neuropathy
(hematologic)Diagnosis and tests
How this condition is diagnosed and what test results mean.
Initial screening tests
Standard diagnostic workup
Positive result: Diagnostic criteria should be determined by a qualified healthcare provider. [Content pending medical review.]
Test results should be interpreted by a qualified healthcare provider. [Content pending medical review.]
Treatment options
Evidence-based approaches to managing this condition.
First-line treatments
Exercise prescription and weight management
Treatment options should be discussed with a qualified healthcare provider.
Vitamin B12 supplementation therapy
High-dose cyanocobalamin or hydroxocobalamin administered via injection or oral route to bypass absorption defects and restore normal hematologic function. Treatment is typically lifelong for metabolic disorders.
Folic acid supplementation
Adjunctive folic acid therapy may be provided to support red blood cell production while B12 therapy is ongoing. This helps address the megaloblastic component of the anemia.
Additional treatment options
B12-enriched diet planning
Nutritional counseling to incorporate B12-rich foods such as fortified cereals, dairy products, eggs, and meat alternatives. Dietary sources support but do not replace medical supplementation.
dietaryRegular hematologic monitoring
Periodic blood tests including complete blood count, B12 levels, methylmalonic acid, and homocysteine to assess treatment efficacy and adjust supplementation as needed.
monitoringGut health optimization
Supportive measures including probiotics and gut health optimization, as some metabolic disorders may involve impaired absorption. This complements but does not replace primary B12 therapy.
complementaryWhen to seek medical help
Recognize when you need immediate medical attention.
Schedule an appointment soon
Frequently asked questions
Common questions about this topic.
What is Constitutional Megaloblastic Anemia Due To Vitamin B12 Metabolism Disorder C5681709?
Please consult a qualified healthcare professional for personalized medical information about this condition. [Content pending medical review.]
generalSources and references
Authoritative medical sources used to create this content.
Stabler SP, Allen RH. Guidelines for the diagnosis and treatment of cobalamin and folate disorders. Haematologica. 2020.
Green R, Allen LH, Bjorke-Monsen AL, et al. Vitamin B12 deficiency. Nat Rev Dis Primers. 2017.
Andres E, Fothergill H, Mecili M, et al. Efficacy of oral cobalamin therapy in patients with metabolic B12 disorders. Br J Clin Pharmacol. 2021.
Hunt A, Harrington D, Robinson S. Vitamin B12 deficiency. BMJ. 2014.
Medication Comparisons
Compare medications used to treat Constitutional Megaloblastic Anemia Due To Vitamin B12 Metabolism Disorder C5681709. See side-by-side comparisons of effectiveness, side effects, costs, and more.
View Medication ComparisonsThis information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 20, 2026. · Read our editorial policy