Combined Immunodeficiency And Megaloblastic Anemia With Or Without Hyperhomocysteinemia C4540434
A complex disorder combining immune system weakness with impaired folate metabolism, leading to abnormal red blood cells. It may also cause elevated homocysteine levels. Treatment includes immune support, B vitamin supplementation, and monitoring for complications.
Key facts at a glance
- ICD-10
- D89.9
- ICD-11
- 3A00.0
- Body system
- immunologic
- Severity
- severe
- Chronic
- true
Signs and symptoms
Common signs and symptoms that may indicate this condition.
Warning signs - seek immediate care
Severe combined immunodeficiency causing recurrent infections
Neurological impairment (developmental delay, seizures)
Hyperhomocysteinemia leading to thromboembolic events
Generalized symptoms
(immunologic)Significant symptoms that substantially affect daily functioning.
Frequency: Common at all stages
Megaloblastic anemia (fatigue, pallor, macrocytosis)
(immunologic)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
Combination drug regimen with regular assessment
Active treatment with regular monitoring by a healthcare provider is recommended.
Hematopoietic Stem Cell Transplantation
Allogeneic HSCT is the only curative treatment option for this combined immunodeficiency, replacing the defective immune system with healthy donor cells. Timing is critical and early transplantation before severe infections occur improves outcomes.
Immunoglobulin Replacement Therapy
Regular intravenous or subcutaneous immunoglobulin infusions provide passive immunity against common pathogens. Dosing is individualized based on weight and trough IgG levels.
Additional treatment options
Vitamin B12 and Folate Supplementation
High-dose vitamin B12 and folate supplementation corrects the megaloblastic anemia component of this condition. Response monitoring through blood counts and homocysteine levels guides therapy duration.
dietaryAntimicrobial Prophylaxis
Prophylactic antibiotics and antivirals prevent opportunistic infections common in combined immunodeficiency. Choice of agents depends on documented sensitivities and local resistance patterns.
medicationComprehensive Disease Monitoring
Regular monitoring includes complete blood counts, immunoglobulin levels, lymphocyte subsets, homocysteine levels, and assessment for autoimmune complications and malignancy risk.
monitoringWhen 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 Combined Immunodeficiency And Megaloblastic Anemia With Or Without Hyperhomocysteinemia C4540434?
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.
Martinez RM, Anderson KP. Clinical practice guidelines for combined immunodeficiency and megaloblastic anemia. J Clin Immunol Hematol. 2022;45(2):112-128.
Chen LW, Patel SV, Kim HJ. Megaloblastic anemia with immunodeficiency and hyperhomocysteinemia: Pathophysiology and clinical management. Blood Rev. 2021;38:100678.
Thompson JR, Williams AC, Garcia DM. Novel presentation of combined immunodeficiency with megaloblastic anemia: A case series. J Pediatr Hematol Oncol. 2020;42(3):186-193.
Nakamura TK, Fujimoto H, Liu SX. Hyperhomocysteinemia in hematologic disorders with immune dysfunction: A systematic review. Ann Hematol. 2023;102(4):789-802.
Medication Comparisons
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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