Effects of Folic Acid Antagonist Therapy on Urinary Excretion of Formic Acid by Humans.

Abstract
An enzymatic procedure was employed to demonstrate the presence of formic acid in small quantity in the urine of normal human subjects and of patients with a variety of disease states. Formic acid excretion is markedly elevated in patients with acute leukemia receiving the folic acid antagonist, amethopterin (Methotrexate).