What I can figure out this is a standard test use for the DUI blood/TCH ratio 8ng/ml is the limit so 4ng/ml at half shelf life is 2....Not sure but tring to put it together. She under contract using narcs in PA. So Dr fishing asked her if she uses She has FULL BLOWN BECHET'S DISEASE. Having gastro problems. Dr commented that MJ can cause nausea. (Yes bs mexican crap grass) WTH she's on methitrexate/predisone/opiates/benzo/ and other meds. I think long term use of these meds would cause anyone's stomach to hurt. DUH! Looking for someone to talk too. Frustrated.Hope I'm in the right place. Friend had a urine test with these numbers: What does THC 4 and cannabinoids 200 mean?