The Schilling test.
D000752:Anemia, Pernicious / Q000150:complications; D002446:Celiac Disease / Q000150:complications; D003424:Crohn Disease / Q000150:complications; D005919:Glomerular Filtration Rate; D006801:Humans; D007437:Intrinsic Factor; D012546:Schilling Test; D014805:Vitamin B 12 / Q000652:urine
D007437:Intrinsic Factor; D014805:Vitamin B 12