5036 Metformin-associated vitamin B12 deficiency as a potential cause of recurrent chronic subdural hematoma

Disclosure: Y. Thewjitcharoen: None. P. Chongvoranond: None. S. Nakasatien: None. S. Krittiyawong: None. T. Himathongkam: None. Background: Metformin-associated vitamin B12 deficiency is now considered a common side effect especially in those receiving a higher dose and those with existing risk factors. Many cases of vitamin B12 deficiency are overlooked or sometimes even misdiagnosed especially in patients with non-classical manifestations such as mild anemia without macrocytosis, neuropsychiatric manifestations, and symptoms of frailty. Among elderly individuals, the spectrum of symptoms and signs suggestive of vitamin B12 deficiency might be nonspecific and may occur because of other diseases. Due to the aging population, the incidence of chronic subdural hematoma has been on the rise. Here, we present a case of metformin-associated vitamin B12 deficiency as a potential underlying cause of gait instability leading to a recurrent chronic subdural hematoma. Clinical case: An 84-year-old man with well-controlled type 2 diabetes mellitus presented to the outpatient department with dizziness and fatigue for 2 weeks. The patient did not report any recent trauma. He had been in his usual state of health until 10 months ago when he began to have frequent fallings and fatigue. Acute-on-chronic subdural hematoma was found from computed tomography of the head. The patient’s history was significant for type 2 diabetes mellitus with metformin treatment 1,700 mg/day for more than 25 years, post-transcatheter aortic valve implantation for aortic stenosis, and coronary artery disease. He had been on dual antiplatelet therapy and proton pump inhibitor. Subsequent evaluations demonstrated mild normocytic anemia, mild thrombocytopenia, undetectable plasma vitamin B12 level, elevated plasma homocysteine, and normal folate level. Improvement in neurological symptoms occurred within one week of vitamin B12 replacement and surgical hematoma evacuation. Conclusions: Our case highlights the importance of assessing vitamin B12 status among elderly patients taking metformin and it is essential for clinicians to maintain a high index of suspicion in elderly patients with prolonged use of metformin presented with gait instability and frequent fallings. With the ageing of society and the continuing growth of the older population, metformin-associated vitamin B12 deficiency is expected to have an emerging complication in the future. Routine measurement of vitamin B12 level for metformin-treated individuals should be considered. Presentation: 6/1/2024