My wife, who takes morphine sulfate ER and oxycodone IR for chronic pain. She does a urine test every month. For the first time in several years, 10+, her results showed a positive result for codeine, 107 ng/mL. I found an article that said a small amount of codeine may show up in patients taking high doses of morphine due to possible impurities in manufacturing. Is this correct? Has anyone else run in to this?? My wife does not take any illicit medications so we are perplexed over this result and are wondering what her doctor is going to do, if anything, at her next appointment next month, 12/2016! Her doses are 45mgs of morphine sulfate ER two times a day and 5mgs of oxycodone three times a day. Any links to articles that may explain this phenomenon would be greatly appreciated!!