This test is used to monitor the treatment of patients with methylmalonic acidemia due to either a defect in methylmalonyl-CoA mutase, or in the transport or processing of cobalamin (B12). Methylmalonic acid levels are also assessed as part of a comprehensive assessment of B12 deficiency.

Note: This test is not appropriate for the initial evaluation of patients suspected clinically of having methylmalonic acidemia; for these cases, please order urine organic acids.