Vitamin B₁₂ Therapy in Older Adults and Misconception of Its Inappropriateness—Reply

In Reply We thank Arendt and colleagues and Stall and colleagues for their letters on our study.¹ We agree that diagnosing vitamin B₁₂ deficiency can be challenging in elderly patients. To mitigate this, we used a threshold of 221 pmol/L, the least restrictive value for B₁₂ deficiency according to the National Health and Nutrition Examination Survey.^1,2 It is also in keeping with Canadian practice guidelines on B₁₂ deficiency, which suggest that symptoms of deficiency are rare with a serum B₁₂ 221 pmol/L or greater.³ We also believe that using methylmalonic acid and homocysteine levels as surrogates for deficiency does not reflect real-world practice, given their limited availability, cost, and poor sensitivity with increasing age.⁴