The Measurement of Folic Acid Activity in Serum: A Diagnostic Aid in the Differentiation of the Megaloblastic Anemias

Abstract
A modified L. casei microbiologic assay for the "folic acid" content of fasting serum appears to reflect the presence or absence of folic acid deficiency in patients with megaloblastic anemia of various causes. Advantages of this assay method for fasting serum "folic acid" level over other procedures presently in use for evaluating possible folic acid deficiency are discussed.