Creatinine Calculator Formula:
   CRCL = (140 - A) * W * r /(72 * C)
Where:
   A: Age, in years
   W: Body weight, in pounds (lbs)
   C: Serum Creatinine Level, in mg/dL
   r: Sex difference ratio, 0.85 for woman, and 1 for man
   CRCL: Creatinine Clearance Rate, in mL/min