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Case Reports
. 2025 Apr 2;19(1):151.
doi: 10.1186/s13256-025-05149-7.

A long-standing undiagnosed case of vitamin B12 deficiency: a case report

Amirhossein Mesgarankarimi  1 , Maryam Rezapour  2 , Nasim Tabrizi  3
Affiliations
Case Reports

A long-standing undiagnosed case of vitamin B12 deficiency: a case report

Amirhossein Mesgarankarimi et al. J Med Case Rep. .

Abstract

Background: Pernicious anemia, an autoimmune disease, presents with gradual, nonspecific symptoms, often leading to delayed diagnosis owing to its overlap with other conditions and variability in laboratory findings, such as neurological symptoms without anemia or macrocytosis.

Case presentation: This case describes a 40-year-old Iranian woman with a decade-long history of nonspecific symptoms, including fatigue, widespread musculoskeletal pain, paresthesia, cognitive disturbances, and optic neuritis; misattributed to conditions such as fibromyalgia, hypothyroidism, and autoimmune diseases. Despite annual monitoring for normocytic anemia, her critically low vitamin B12 levels (< 150 pg/mL) and a diagnosis of pernicious anemia were identified only after persistent symptoms prompted further evaluation, revealing atrophic gastritis as the underlying cause. Neurologic improvement with parenteral B12 therapy, alongside management of fibromyalgia, emphasizes the importance of considering vitamin B12 deficiency even in the absence of classic hematologic findings.

Conclusion: This case highlights the diagnostic challenges of pernicious anemia, where nonspecific symptoms and overlapping comorbidities obscure diagnosis, underscoring the need for a systematic, multidisciplinary approach and timely recognition of vitamin B12 deficiency to prevent irreversible complications.

Keywords: Case report; Electric shock-like sensations; Forgetfulness; Mental slowing; Misdiagnosis; Nutrient deficiency; Optic neuropathy.

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Conflict of interest statement

Declarations. Ethics approval and consent to participate: Due to the observational nature of this case report, which does not involve any interventions or experimental procedures, formal ethical approval was not required. Consent for publication: Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal. Competing interests: The authors declare that they have no competing interests.

Figures

Fig. 1
Fig. 1
Visual field test. (A) Visual field map. (B) Glaucoma hemifield test. (C) Deviation maps. (D) Statistics
Fig. 2
Fig. 2
High-definition optical coherence tomography scans. (A) Optic nerve head and retinal nerve fiber layer analysis for both eyes. (B) Macula thickness analysis. (C) High-definition images. (D) High-definition images (alternate view)
Fig. 3
Fig. 3
A Endoscopic examination report. (B) Gastric mucosal biopsies and pathological report
See this image and copyright information in PMC

References

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