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Assessing Microglial Phagocytosis of Myelin Debris in vitro Under Repeated Magnetic Stimulation
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Macro-B12 masking B12 deficiency.

Bruce H R Wolffenbuttel1, Anneke C Muller Kobold2, Agata Sobczyńska-Malefora3,4

  • 1Department of Endocrinology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands bwo@umcg.nl.

BMJ Case Reports
|January 14, 2022
PubMed
Summary
This summary is machine-generated.

Elevated serum vitamin B12 can stem from supplementation or rare macro-B12 complexes. This case highlights how macro-B12 can mask underlying B12 deficiency, causing persistent neurological symptoms.

Keywords:
metabolic disordersvitamins and supplements

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Area of Science:

  • Clinical Biochemistry
  • Hematology
  • Neurology

Background:

  • Elevated serum vitamin B12 (cobalamin) often results from supplementation or underlying conditions like liver disease or malignancy.
  • Macro-B12, a complex of vitamin B12 with binding proteins and immunoglobulins, is a less common cause of high B12 levels.
  • Accurate B12 assessment is crucial for diagnosing and managing deficiencies and related neurological disorders.

Observation:

  • A young woman with a history of B12 deficiency experienced recurring neurological symptoms after discontinuing B12 injections.
  • Despite symptom recurrence and treatment cessation, her serum B12 concentrations remained persistently elevated above the assay's upper limit.
  • These findings prompted an investigation into the cause of the anomalous B12 readings.

Findings:

  • The persistently elevated serum B12 levels were attributed to the presence of macro-B12.
  • Macro-B12 formation interfered with standard B12 assays, leading to falsely high readings.
  • This complex formation effectively masked the patient's underlying B12 deficiency, despite clinical signs.

Implications:

  • This case underscores the importance of considering macro-B12 in patients with unexplained elevated serum B12, especially when clinical symptoms contradict lab results.
  • Recognizing macro-B12 is critical for accurate diagnosis and appropriate treatment of vitamin B12 deficiency.
  • Further research into the prevalence and clinical significance of macro-B12 is warranted to improve diagnostic strategies.