A continuous Glomerular Filtration Rate (GFR) estimation system may include a Foley catheter, a continuous urine creatinine sensor, and a urine output monitor. The continuous GFR estimation system computes creatinine clearance as CrCl = (U cr x U vol )/(P cr X I mim ), where U cr is urine creatinine in mg/dL, U Vol is urine volume in mL, P cr is plasma (serum) creatinine in mL, and I min is time in minutes. A Foley catheter may be used to withdraw urine from the bladder. The urine may be delivered to a urine output monitoi that provides the U vol value over a time I min . Attached to the catheter is the flow-thiough continuous urine creatinine sensor for providing the U cr value.The remaining parameter is P cr .Because serum creatinine levels do not change rapidly over time, a blood sample may be withdrawn prior to the start of the continuous GFR to obtain the P C r value.