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Vitamin B12 malabsorption: causes, symptoms, diagnosis, treatment
Last reviewed: 07.07.2025
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There are several congenital forms of cobalamin transport and absorption defects.
- Hereditary deficiency of intrinsic factor.
- Impaired transport of cobalamin through the enterocyte (Immersland-Gresbeck syndrome).
- Transcobalamin-2 (cobalamin transporter) deficiency.
ICD-10 code
D51. Vitamin B 12 - deficiency anemia.
Symptoms
Symptoms of vitamin B12 malabsorption develop from the first months of a child's life. Weakness, pallor, delayed physical development, diarrhea are noted. Neurological disorders are noted 6-30 months after the onset of the first symptoms: mental retardation, neuropathy, myelopathy.
Acquired vitamin deficiencies (due to gastric resection) are less severe and do not cause neurological disorders.
Diagnostics
In addition to megaloblastic anemia, blood analysis reveals pancytopenia, granulocyte dysfunction with defects in humoral and cellular immunity. Sometimes leukemia is mistakenly diagnosed due to the detection of immature leukocyte precursors in hypocellular bone marrow. Serum transcobalamin levels are usually within normal limits.
Treatment
Hydroxocobalamin is prescribed in a high dose - 0.5-1.0 mg/kg daily until hematological remission, and then 2 times a week. Folic acid is used at 15 mg orally 4 times a day. The use of folates without cobalamin in this disease is contraindicated.
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