I have been seeing a doctor at my pain clinic for over 10 yrs. As normal, random urine test are done to see if the drugs I am taking are in my system. Last month the test came back that I had NOT taken one of these drugs ( oxycodone NOT OxyContin) when in fact I had. I had not taken any the day of the test and very few for about a week prior to test because of stomach virus. I had to re take the test and if it comes back again I do not have it in my system their could be a problem. I take my meds, I take them as prescribed. I also though have other health issues including lupus, non functioning thyroid, no large intestine, diabestes. Could any of these things affect the urine test? Thank You ~S~