Two-Hour Creatinine Clearance and Glomerular Filtration Rate Estimated from Serum Cystatin C and Creatinine in the Elderly to Preoperative Period

Introduction: The utility of estimates of glomerular filtration rate based on creatinine and cystatin C serum levels to assess renal function in older surgical patients remains to be determined. Objective: To determine whether 2h-creatinine clearance (CrCl-2h) can be an adequate substitute for glomerular filtration rate estimates obtained by measuring serum cystatin C and creatinine in the elderly at preoperation. Methods: A total of 102 consecutive elder patients undergoing pre-anesthesia evaluation for routine surgeries were included. Study subjects were allocated into three groups: Group 1 (G1)—hypertensive diabetic patients, Group 2 (G2)—hypertensive patients, and Group 3 (G3)—non-hypertensive and non-diabetic patients. Two-hour urine collection was performed and CrCl-2h adjusted for ultrasonic residual bladder volume was estimated. GFR was estimated based on creatinine and cystatin C serum levels. Bland-Altman analysis was used to compare methods. Results: The mean difference between the evaluated methods and CrCl-2h was ·min-1·1.73 m-2 for Cys-GFR, and >20 mL·min-1·1.73 m-2 for Cr-GFR in all groups. CrCl-2h adjusted for ultrasonic residual bladder volume did not differ from non-adjusted CrCl-2h in none of the groups. Conclusion: Two-hour creatinine clearance was not an adequate substitute for GFR estimates based on creatinine and cystatin C serum levels in older patients at preoperation. The ultrasonic assessment of residual bladder volume had no significant influence on the calculation of two-hour creatinine clearance.