Abstract
Five patients with megaloblastic anemia due to vitamin B12 and/or folic acid deficiency who excreted abnormally large quantities of formimino-glutamic acid (FGA) after a 20 g oral L-histidine HCL load were studied. FGA excretion was markedly reduced in all 4 subjects given 20 g DL-methionine and in both subjects given 20 g glycine together with L-histidine HC1. Of 3 subjects given 20 g DL-serine, 1 showed no reduction in FGA excretion and 2 showed moderate reduction.