A 21-year-old Japanese woman was admitted to our hospital because of proteinuria and hematuria. She had been diagnosed at birth with persistent cloaca and congenital esophageal atresia, and underwent enterostomy, cystostomy, and radical esophageal surgery, followed by repair of persistent cloaca and colostomy closure 2 years later. She was followed-up at the pediatric surgery and urology department, and developed with no major problems. Proteinuria and hematuria were detected at routine examination 7 months prior to admission for the first time. No urological problems were detected at a visit to the urology department 3 months before admission. She had mild edema before admission; however its onset had been gradual and it was therefore not clear when the edema had started.
On admission, the patient’s height was 158.6 cm, her weight was 53.0 kg, and her blood pressure was 101/80 mmHg. Physical examination revealed an abdominal midline operation scar and pretibial pitting edema. Urinary examination revealed a protein level of 3+ and 5–9 red blood cells per high-power field. Her urine protein/creatinine ratio was 3.38 g/gCr, blood urea nitrogen was 13.2 mg/dL, serum creatinine was 0.73 mg/dL, and serum albumin was 3.6 g/dL. Serum C3 was 25 mg/dL, C4 was 18.5 mg/dL, and 50% hemolytic unit of complement (CH50) was 13 U/mL. Chromosome G banding revealed a normal karyotype 46XX. Kidney ultrasound showed no kidney deformity. Kidneys size was normal.
A renal biopsy contained 24 glomeruli, all of which showed moderate to severe mesangial hypercellularity and increased homogenous materials in the mesangium. Which were positive with periodic acid-Schiff and were negative with methenamine silver (Fig. ). One glomerulus revealed fibrous crescent formation, and 11 showed segmental double contour of glomerular basement membrane. Immunofluorescence microscopy showed slight staining for fibrinogen, but no staining for IgG, IgA, IgM, kappa light chain and lambda light chain (Fig. ). Electron microscopy showed massive granular deposits in the mesangial area and some subepithelial area (Fig. ). According to these findings, we speculated fibronectin glomerulopathy as a diagnosis. Thus, we performed immunoassays using anti-human fibronectin antibodies. The staining with IST-4, which detects plasma and cell-associated fibronectin, was positive but no staining was observed with IST-9, which stains only cell-associated fibronectin (Fig. ). The mesangial deposits were therefore shown to comprise plasma fibronectin. The patient was finally diagnosed as fibronectin glomerulopathy.
Her family history was investigated further. Although her mother and younger sister had previously been detected to have proteinuria, their urine and blood tests were normal. Her father showed no urinary abnormalities and normal kidney function at his annual health examination. Given that no family history of renal disease could be identified, the current case was determined to be sporadic. The patient and her mother underwent genetic testing of the FN1 gene, which revealed no abnormalities.
Treatment with an angiotensin II receptor antagonist and a sodium-restricted diet were started. However, 10 months after the kidney biopsy, the patient’s proteinuria had increased and her renal function was deteriorated, with a urine protein/creatinine ratio of 9.52 g/gCr, serum creatinine 0.86 mg/dL. Her serum albumin decreased to 2.0 g/dL.
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 female, which means that the gender coefficient is 0.85.
The patient is 21 years old. 
The concentration of creatinine is 0.73 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 158.6 cm, which is 158.6 cm * 1 m / 100 cm = 1.586 m. The patient's weight is 53.0 kg. The patient's bmi is therefore 53.0 kg / (1.586 m * 1.586 m) = 21.07 kg/m^2.The patient's BMI is 21.1, 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 51.114 kg.

Using the Cockcroft-Gault equation:
CrCl = ((140 - age) * adjusted weight * gender_coefficient) / (serum creatinine * 72).
Plugging the patient's values gives us ((140 - 21) * 51.114 * 0.85) / (0.73 * 72) = 98.367 mL/min. Hence, the patient's creatinine clearance is 98.367 mL/min.