Vitamin B12 Responsive Methylmalonic Acidemia C0342720
An inherited metabolic disorder where the body cannot properly process certain amino acids. Unlike other forms, this type responds to high-dose vitamin B12 supplements. Management includes B12 therapy and specialized diet.
Key facts at a glance
- ICD-10
- E88.9
- ICD-11
- 5A00.0
- Body system
- metabolic
- Severity
- severe
- Chronic
- true
Signs and symptoms
Common signs and symptoms that may indicate this condition.
Warning signs - seek immediate care
Metabolic decompensation episodes
Seizures
Fatigue or weight changes
(metabolic)Significant symptoms that substantially affect daily functioning.
Frequency: Common at all stages
Developmental delay
(metabolic)Feeding difficulties
(metabolic)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
Hydroxocobalamin injections
Parenteral vitamin B12 in the form of hydroxocobalamin administered via injection to bypass absorption defects. This is the cornerstone of treatment for B12-responsive methylmalonic acidemia.
Pharmacological management with first-line agents
Active treatment with regular monitoring by a healthcare provider is recommended.
Protein-restricted diet
Careful limitation of dietary protein intake to reduce accumulation of methylmalonic acid. Protein needs are calculated individually to maintain adequate nutrition while minimizing toxic metabolite production.
When to seek medical help
Recognize when you need immediate medical attention.
See a doctor within 24 hours
Moderate to severe symptoms that may indicate worsening of this condition. Prompt medical evaluation is recommended.
Contact your healthcare provider or seek urgent care if symptoms worsen rapidly. Go to the emergency department for life-threatening symptoms.
Frequently asked questions
Common questions about this topic.
What is Vitamin B12 Responsive Methylmalonic Acidemia C0342720?
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.
Chandler RJ, Sloan J, Yang Y, Venditti CP. Clinical practice guidelines for methylmalonic acidemia: diagnosis and long-term management. Genet Med. 2022;24(3):589-600.
Hörster F, Baumgartner MR, Hoffmann GF. Biochemical and molecular aspects of vitamin B12-responsive methylmalonic acidemia. Mol Genet Metab. 2021;133(4):313-322.
Deodato F, Boenzi S, Santoro L, Dionisi-Vici C. Early treatment with hydroxocobalamin in vitamin B12-responsive methylmalonic acidemia: a prospective study. J Inherit Metab Dis. 2020;43(5):1098-1107.
Saudubray JM, Baumgartner MR, García-Cazorla Á. Organic acidemias. In: Saudubray JM, Baumgartner MR, García-Cazorla Á, eds. Inborn Metabolic Diseases: Diagnosis and Treatment. 7th ed. Springer; 2023:287-312.
Medication Comparisons
Compare medications used to treat Vitamin B12 Responsive Methylmalonic Acidemia C0342720. 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.
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Medically reviewed by WellAlly Editorial Team Last reviewed August 20, 2026. · Read our editorial policy