Letter: Negative guaiac test after glyceryl guaiacolate.
D005189:False Positive Reactions; D006138:Guaiac; D006140:Guaifenesin / Q000494:pharmacology*; D006801:Humans; D009780:Occult Blood / Q000379:methods*
D006140:Guaifenesin; D006138:Guaiac