Functional Liver Challenge Tests check the ability of the liver to detoxify and eliminate drugs and other chemicals, even candida metabolites like mannan.
There are two basic ways you can do this, you can do a "challenge" or a "non-challenge" test. With a challenge test, a substance like acetaminophen or caffeine is taken in and afterwards a urine sample is collected and sent to a laboratory. The elimination rates of a certain markers in your urine are then assessed and a picture of the function of your liver's detoxification pathways is made.
A non-challenge test assesses organic acids like d-glucaric (Phase-2) and mercapturic (Phase-1) which comprise your two main liver detoxification pathways.
Your naturopathic doctor should be able to organise this test for you, and labs who can do this include Doctor's Data or MetaMetrix. I prefer the non-challenge test myself. This test will give you a good picture of the functional capacity of your liver's detox capability. Hope this helps.