Synthetic urine

I am getting reports from some of my occupational medicine clinics that perform pre-employment drug screen that they are getting a lot of suspected synthetic urine come through their lab.  They are currently using a Urine Check 7 adulteration strip and these suspected urines are passing.  I am seeing that there are some manufacturer's that are using dehydrated human urine in their test kits that can pass the specific gravity and creatinine part of the adulteration strip.  Does anyone else have experience with this and how do you handle it?