i was on norco, a 13 day supply, ran out on day 12.. was tested day 15 & nothing showed up in my urine. i have arachnoiditis which causes over active bladder, so i go to the bathroom way more than the normal person, my urine is always so clear because of it. dr is now refusing to treat me because of a negative urine. can urinating so often result in a negative test? another test was positive for opiates when he gave mea 15 day supply,. i am at a loss. he said i have to have a nephrolgist confirm this. is this possible? i took my medication as directed except for after he gave me injections in my back, i was on the couch in extreme pain for a whole weekend, which i did take a few extra. that is why i ran out on day 12 instead of day 13.