関連ワード:  reference values of urea    reference values of urea creatinine uric acid    normal values of urea    normal values of urea and creatinine    normal values of urea creatinine and uric acid    normal values of urea in blood    reference range of urea and creatinine    normal values of urea in urine    normal values of urea and creatinine in blood    reference range of urea in mg dl