The patient is a 78-year-old male patient with renal disease from 9 years ago (March 2005). He has lived in Semnan, Iran. His medical records were reviewed in October 2014. Laboratory findings in the patient at first were as follows: BUN = 22, Cr = 1.3, weight: 60 kg, height: 166 cm, blood pressure 145/95 mmHg. The patient was treated. The BUN and creatinine levels gradually increased and reached to BUN = 43 and Cr = 4 thirty months after the first referral. All laboratory tests were performed in a medical diagnostic laboratory using the calibrated equipment and common methods. The BUN and creatinine levels were measured by auto analyzer TC-6062 manufactured by Tecom Co, China. Blood pressure was measured by the Riester sphygmomanometer (Germany). At that time he had referred for arteriovenous graft and an arteriovenous fistula made by a surgeon. Six months later he had a functional fistula. Patients were treated with the conventional treatment and Eprex. Specific variables in this case were creatinine and GFR. Blood pressure controlled in the range of 110/80 mmHg. The patient's GFR decreased from 20 to 14 cc/min and his last blood pressure was 140/80 mmHg. The mean serum creatinine level was 3, maximum 4.2 and minimum 1.5. At present, the patient is in stage 4 of CKD and under usual medical treatment.
The formula for computing Cockcroft-Gault is given by CrCl = ((140 - age) * adjusted weight * (gender_coefficient)) / (serum creatinine * 72), where the gender_coefficient is 1 if male, and 0.85 if female. The serum creatinine concentration is in mg/dL.
The patient's gender is male, which means that the gender coefficient is 1.
The patient is 78 years old. 
The concentration of creatinine is 1.3 mg/dL. 
The formula for computing the patient's BMI is (weight)/(height * height), where weight is the patient's weight in kg and height is the patient's height in m.
The patient's height is 166.0 cm, which is 166.0 cm * 1 m / 100 cm = 1.66 m. The patient's weight is 60.0 kg. The patient's bmi is therefore 60.0 kg / (1.66 m * 1.66 m) = 21.774 kg/m^2.The patient's BMI is 21.8, indicating they are normal weight.
Because the patient is normal, we take take minimum of the ideal body weight and the patient's body as the patient's adjusted weight for the Cockroft-Gault Equation. Hence, the adjusted body weight is the minimum of the two giving us an adjusted body weight of 60.0 kg.

Using the Cockcroft-Gault equation:
CrCl = ((140 - age) * adjusted weight * gender_coefficient) / (serum creatinine * 72).
Plugging the patient's values gives us ((140 - 78) * 60.0 * 1) / (1.3 * 72) = 39.744 mL/min. Hence, the patient's creatinine clearance is 39.744 mL/min.