Renal Function Assessment in the Era of Chronic Kidney Disease: Renewed Emphasis on Renal Function Centered Patient Care

Purpose

Chronic kidney disease is more common than previously appreciated and it is now established as a major independent contributor to mortality. Serum creatinine is known to be an inaccurate reflection of the presence or development of chronic kidney disease. Since urologists frequently treat patients with coexistent chronic kidney disease, we reviewed the merits and limitations of the current methods to estimate renal function, and recent data indicating the importance of optimizing renal function during treatment.

Materials and Methods

A comprehensive literature review was performed to evaluate the laboratory, computational and imaging techniques for renal function estimation.

Results

Approximately 30% of elderly patients with normal serum creatinine (1.4 mg/dl or less) have chronic kidney disease based on an estimated glomerular filtration rate of less than 60 ml per minute per 1.73 m². The National Kidney Foundation currently recommends using a creatinine based estimate of glomerular filtration rate (eg Modification of Diet in Renal Disease formula) and has advocated a standardized classification for chronic kidney disease. Chronic kidney disease has been independently related to morbid cardiac events and all cause mortality in a dose dependent fashion, even after controlling for a variety of potentially confounding factors such as hypertension and diabetes. Many urological interventions can precipitate or exacerbate chronic kidney disease, most notably radical nephrectomy which is greatly overused.

Conclusions

Practicing urologists should be cognizant of current methodologies to diagnose chronic kidney disease and its profound implications. Estimation of renal function is better using a serum creatinine based formula than individual serum creatinine values. Treatment goals should not be limited to avoidance of dialysis, but should also include greater efforts to optimize renal function in all patients and early referral for nephrological consultation.

Key Words: kidney failure, chronic, glomerular filtration rate, creatinine, nephrectomy, patient care

Abbreviations and Acronyms: CKD, chronic kidney disease, CrCl, creatinine clearance, GFR, glomerular filtration rate, MDRD, Modification of Diet in Renal Disease, NHANES, National Health and Nutrition Examination Survey, NKF, National Kidney Foundation, sCr, serum creatinine level, SRM, small renal mass