I have had to renew many DOT med cards involving a DOT physical throughout years. They always told me it was to check your kidneys, etc., not drugs. With that being said, I have been on pain killers for years now for a disability I have developed, and the dr. wrote ON my DOT med card; driver takes vicodin for pain.. also, when they did the urine test, I was never questioned about the tramadol or Adderall my primary dr. had prescribed me. So, if it were a drug test, I would have had to verify my RX for the 2 drugs that weren't mentioned on the med card.