RESUMO
INTRODUCTION: Hemorrhagic fever with renal syndrome (HFRS) is a globally prevalent infectious disease caused by the hantavirus in rodents. CASE STUDY: This report describes a case of a 36-year-old male presenting with elevated ferritin, vitamin B12, and folic acid deficiency during the early onset phase of HFRS. Despite normal renal function at admission, the patient exhibited persistent fever and thrombocytopenia, leading to a potential misdiagnosis of an atypical HFRS presentation. Abnormal serum levels of ferritin, vitamin B12, and folic acid served as early indicators of renal dysfunction in patients with HRFS. The patient's condition improved rapidly with a combination of vitamin B6, methyl cobalamin, and folic acid, as evidenced by a subsequent decrease in the ferritin levels, from 3000 to 600 ng/mL, on days 4 and 24, respectively, and an increase in the vitamin B12 and folic acid levels to 200 pg/mL and 36.7 ng/mL, separately. CONCLUSIONS: These findings suggest that ferritin, vitamin B12, and folic acid have the potential to serve as biomarkers for HFRS and play a predictive role in the diagnosis and treatment of the disease.