Source:http://linkedlifedata.com/resource/umls/id/C0018302
MSH: Resin from wood of certain species of GUAIACUM. It is used as clinical reagent for occult blood.,NCI: A substance from a type of tree called Guaiacum that grows in the Caribbean. Guaiac is used in the fecal occult blood test (a test for blood in human stool samples).