the folate status of 29 healthy control subjects , 16 rheumatoid arthritis ( ra ) patients taking methotrexate ( mtx ) , and 20 ra patients who were not being treated with mtx was estimated by an assay of the folate-dependent enzymatic synthesis of serine from formate and glycine , which is termed the c1 index .
C0003873
ra
C0025677
mtx