In addition, the enz-PADs were also analysed with 3 levels of creatinine, 11.6 mg dL1 (n¼20), 172.0 mg dL1 (n¼20) and 328.2 mg dL (n¼20), from real urine samples. The results of the within-day precision with CVs of 14.2%, 6.9% and 5.9% were obtained when evaluated with the abovementioned three urine samples, respectively. The between-day precision with CVs of 16.6%, 6.4% and 6.1% was obtained when evaluated for the abovementioned real urine samples with different levels of creatinine assayed on ten consecutive days, respectively.