CREATININE-BASED “BEDSIDE SCHWARTZ” EQUATION (2009)

eGFR =
0.413 x (height/Scr) if height is expressed in centimeters
OR
41.3 x (height/Scr) if height is expressed in meters

Abbreviations / Units

eGFR (estimated glomerular filtration rate) = mL/min/1.73 m2

Scr (standardized serum creatinine) = mg/dL

Assays

Creatinine is assayed using methods that are traceable to IDMS assigned NIST certified reference materials. To learn more, go to nkdep.nih.gov.

Clinical Use

  • For use in children 1-18 years old.
  • The formula was updated in 2009 and is currently considered the best method for estimating GFR in children. It is known as the “Bedside Schwartz” formula.
  • It is devised for use with creatinine methods with calibration traceable to IDMS. All laboratories should be using creatinine methods calibrated to be IDMS traceable. Nearly all major global manufacturers in the US and other countries now have calibration traceable to an IDMS reference measurement procedure. Thus, older equations for estimating GFR in children and infants are no longer valid.
  • Using the original Schwartz formula [0.55 x (height/Scr]) with a creatinine value from a method with calibration traceable to IDMS will overestimate GFR by 20 to 40%.

References

  1. Schwartz GJ and Work DF. Measurement and estimation of GFR in children and adolescents. J Am Soc Nephrol. 2009; Nov; 4(11): 1832-643.
  2. Schwartz GJ, Munoz A, Schneider MF, et al. New equations to estimate GFR in children with CKD. J Am Soc Nephrol. 2009; 20: 629-637.
  3. Staples A, LeBlond R, Watkins S, Wong C, Brandt J. Validation of the revised Schwartz estimating equation in a predominantly non-CKD population. Pediatr Nephrol. 2010 Nov;25(11):2321-6