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When Fever and Thrombocytopenia Are Not Infectious: A Case of Vitamin B12 Deficiency Mimicking Tropical Fever

Author ORCID Identifier

0009000919988825

Corresponding Author

[email protected]

Abstract

Vitamin B12 deficiency is classically associated with megaloblastic anaemia and neurological manifestations; however, atypical presentations continue to pose diagnostic challenges. Fever in association with thrombocytopenia often prompts evaluation for infectious aetiologies such as dengue, malaria, or sepsis, particularly in tropical settings. We report a case of vitamin B12 deficiency presenting with pyrexia and isolated thrombocytopenia, initially suspected to be an infectious illness. Extensive evaluation failed to reveal an infective cause, and subsequent haematological workup demonstrated megaloblastic changes with low serum vitamin B12 levels. Remarkably, the patient showed rapid defervescence and normalisation of platelet counts following parenteral vitamin B12 therapy. This case highlights an underrecognized presentation of vitamin B12 deficiency mimicking acute febrile thrombocytopenia syndromes. Awareness of this reversible aetiology is essential to avoid misdiagnosis, unnecessary antimicrobial therapy, and delayed treatment.

Publication Date

2026

Publisher

JSS Academy of Higher Education & Research

Conflict of Interest

there is no conflict of interest for this case report 

Keywords

vitamin b12 deficiency, thrombocytopaenia, fever

Word Count

960

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

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