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=(Ucr×Uvol)/Pcr×Tmin), where Ucr is urine creatinine in mg/dL, Uvol is urine volume in mL, Pcr is plasma (serum) creatinine in mg/dL, and Tmin 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 monitor that provides the Uvol value over a time Tmin. Attached to the catheter is the flow-through continuous urine creatinine sensor for providing the Ucr value. The remaining parameter is Pcr. Because serum creatinine levels do not change rapidly over time, a blood sample may be withdrawn prior to the start of the continuous GFR to obtain the Pcr value.