A 43-year old male presented with a history of proteinuria discovered on a routine medical examination in 1985 when he was 22 years old. His medical history was acute pancreatitis at age 17 and hypertension at age 40, and the family history indicated that his nephew had IgA nephropathy. The patient occasionally consumes alcohol, but doesn’t smoke. The patient visited a local doctor and underwent a renal biopsy for suspected active nephritis because of the finding (Table ) of hematuria 3+ protein from pooled urine 0.78 g/day and a plasma creatinine (Cr) level of 1.16 mg/dl [estimated glomerular filtration rate (eGFR) 71 ml/min/1.73 m2]. Pathologic examination revealed IgA nephropathy with partial cellular crescent formation in 1 of the 12 glomeruli, slight mesangial matrix expansion, and mild atrophy of the renal tubule and interstitium. He was followed up without treatment, and the urinary abnormalities resolved spontaneously. He stopped visiting the hospital 3 years after the first visit because of the repeated negative urine analysis and did not visit any other hospital thereafter. He continued to undergo routine medical examinations, which were intermittently positive for microhematuria and proteinuria. His next visit to a medical institution was in 2002 at 38 years of age and revealed urine protein 2+, urine occult blood 1+, plasma Cr 1.13 mg/dl and hypertension. An angiotensin receptor blocker (ARB) was started. After that, he saw a doctor regularly, but hematuria and proteinuria became gradually worse. A relapse of IgA nephropathy was suspected. In March 2009, he was admitted to a hospital for renal biopsy to evaluate the progression of IgA nephropathy.
The patient's general condition at the time of hospitalization was height 163.0 cm, weight 55.0 kg, body mass index 20.7 kg/m2, blood pressure 116/72 mmHg, heart rate 83 beats/min and temperature 36.6 °C. He was lucid with no sign of anemia in the palpebral conjunctiva. No swelling of the throat, abnormal chest auscultation, hard and tender points in the abdominal area or edema of the extremities was observed. Medical examinations (Table ) revealed urine protein 3+ (0.90 g/day), urine occult blood 3+ (RBC 10–19/HPF) and serum Cr 1.63 mg/dl.
Renal biopsy (Fig. ) showed 4 global scleroses, 3 cellular crescent formations and 3 adhesions in 28 glomeruli; moderate expansion of the mesangial matrix; moderate tubular atrophy with mild cell infiltration in the interstitium; and moderate arteriolosclerosis and thickening of interlobular arteries. Immunostaining of IgA confirmed the diagnosis of active chronic-progressive IgA nephropathy.
After admission, the patient was treated with tonsillectomy and steroid pulse therapy. Steroid pulse therapy was given as follows: methylprednisolone was administered continuously at a pulsed dose of 500 mg/day for 3 days, followed by oral prednisolone at a dose of 30 mg continuously for 3 weeks. After completion of the third course, oral prednisolone was initiated at a dose of 30 mg/day every other day after treatment and tapered by 5 mg every 2 months. The after-treatment follow-up was continued for 1 year. The patient underwent tonsillectomy after discharge from the hospital (day 75) and was then followed up at the outpatient clinic. He completed oral prednisolone treatment in approximately a year, but continued taking an ARB during the follow-up period. Clinical remission was achieved 7 months after the initiation of therapy (Table ), and hematuria and proteinuria were no longer observed in this 3-year follow-up period (Fig. ).
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 43 years old. 
The concentration of creatinine is 1.63 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 163.0 cm, which is 163.0 cm * 1 m / 100 cm = 1.63 m. The patient's weight is 55.0 kg. The patient's bmi is therefore 55.0 kg / (1.63 m * 1.63 m) = 20.701 kg/m^2.The patient's BMI is 20.7, 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 55.0 kg.

Using the Cockcroft-Gault equation:
CrCl = ((140 - age) * adjusted weight * gender_coefficient) / (serum creatinine * 72).
Plugging the patient's values gives us ((140 - 43) * 55.0 * 1) / (1.63 * 72) = 45.458 mL/min. Hence, the patient's creatinine clearance is 45.458 mL/min.