text: Males produce approximately 150 μmol to 200 μmol of creatinine per kilogram of body weight per 24 h while females produce approximately 100 μmol/kg/24 h to 150 μmol/kg/24 h. In normal circumstances, all this daily creatinine production is excreted in the urine.
  Creatinine concentration is checked during standard urine drug tests. An expected creatinine concentration indicates the test sample is undiluted, whereas low amounts of creatinine in the urine indicate either a manipulated test or low initial baseline creatinine concentrations. Test samples considered manipulated due to low creatinine are not tested, and the test is sometimes considered failed.