- Adequate renal functions as defined as a serum creatinine of 1.5 mg/dL, urine protein < 100 mg/dL or negative proteinuria, and a calculated creatinine clearance > 55 mL/min based on the following formulas: For males ((140 minus age in years) x weight in kg)/72 x serum creatinine). For females: 0.85 x ((140 minus age in years) x weight in kg)/72 x serum creatinine). Note: Renal function is measured to ensure subjects could meet criteria for use of cidofovir if needed.