Methylmalonic Acid Excretion and Serum Vitamin B12

Abstract
Urinary methylmalonic acid excretion in 12 healthy persons ranged between 0.6 and 4.7 mg per 24 hours; in 10 patients with serum vitamin B12 at or above 70 pg/ml, less than 5 mg of methylmalonic acid was excreted per 24 hours. In a group of 21 patients with serum vitamin B12 below 70 pg/ml, 18 excreted more than 7 mg per 24 hours (7.8–660 mg).