YNHH Laboratory Manual

Reported Glomerular Filtration Rate is an estimate (eGFR) based on serum creatinine value, sex and age, using the abbreviated MDRD (Modification of Diet in Renal Disease) equation. Its ordering and reporting is pursuant to the provisions of the State of Connecticut Public Act 06-120 and.according to the recommendations of the National Kidney Disease Education Program (NKDEP) at the National Institute of Health

It should only be used as a guide to recognize the potential presence of a reduced GFR. It assumes that serum creatinine reflects a steady state and values should only be interpreted by the provider within the clinical context for each patient, including their implications on clinical care. This is relevant for elderly patients who may have lower eGFR values. This is also relevant upon interpreting values reported for hospitalized patients who frequently are not in steady state conditions. In addition, various GFR estimating equations, including MDRD, appear to overestimate true GFR in ill hospitalized patients. Patients with End Stage Renal Disease may have an eGFR value automatically reported by the laboratory system but should be considered an irrelevant value, especially in anuric patients. No values will be reported for patients younger than 18 years

The eGFR could be higher by 21% on average (1.212 MDRD equation factor) for an African-American individual than the value reported. A GFR <60 ml/min/1.73m2 denotes Chronic Kidney Disease (CKD) if present for three or more months. Values above 60 ml/min/1.73m2 will be reported only as GFR > 60 ml/min/1.73m2 given the inaccuracy of estimates at higher GFR levels. A GFR > 60 ml/min/1.73m2 may still be associated with CKD if other abnormalities are present such as proteinuria or microalbuminuria. This estimated GFR value is generated normalized to 1.73 m2. This may not be appropriate for patients with extremes of body size (BSA). MDRD equation-eGFR may be an underestimate in individuals with normal GFR. Additional information is available at http://www.nkdep.nih.gov

Formula utilized at YNHH:

GFR = 186 X (Scr)^-1.154 X (age)^-0.203 X 0.742 (if the subject is female)

References:

1) Stevens L et al: N Engl J Med 2006; 354:2473-83

2) Levey et al: Ann Intern Med 2003;139:137-47

3) Poggio, E et al: Am J Kideny Dis 2005; 46: 242-252

4) National Kidney Disease Education Program. Laboratory professionals: Creatinine Standardization Program. (Accessed July 12, 2006, at http://www.nkdep.nih.gov/labprofessionals/index.htm)

Updated: Sep-2007