title: Letter: Total and free plasma-tryptophan concentration and oral contraception.
mesh_terms: D001921:Brain / Q000378:metabolism; D003276:Contraceptives, Oral / Q000009:adverse effects* / Q000494:pharmacology; D003863:Depression / Q000097:blood / Q000139:chemically induced / Q000209:etiology / Q000378:metabolism; D005260:Female; D006801:Humans; D014364:Tryptophan / Q000096:biosynthesis / Q000097:blood* / Q000378:metabolism; D026681:Vitamin B 6 Deficiency / Q000150:complications
chemical_list: D003276:Contraceptives, Oral; D014364:Tryptophan