What is the difference between Schwartz and Schwartz bedside equations ? And when to use each ?
GFR = k × Height/Serum creatinine
Height represents the body height measured in centimeters, and serum creatinine is measured in mg/dL. The constant k is directly proportional to the muscle component of the body and varies with age based on the laboratory assay used to measure serum creatinine .
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Enzymatic methodology using isotope dilution mass spectrometry – When the serum creatinine is determined using enzymatic methodology, the value for k is 0.413 mg/dL (36.5 micromol/L) for all children with chronic kidney disease between ages 1 and 16 years. This is what called Bedside Schwartz method.
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Jaffe method – When serum creatinine is measured by the Jaffe method, the values for k are:
- Premature infants: through the first year of life: 0.33 mg/dL (29.2 micromol/L)
- Term infants: through the first year of life: 0.45 mg/dL (39.8 micromol/L)
- Children and adolescent girls: 0.55 mg/dL (48.6 micromol/L)
- Adolescent boys: 0.7 mg/dL (61.9 micromol/L)
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Ref:
- Srivastava T, Alon US, Althahabi R, Garg U. Impact of standardization of creatinine methodology on the assessment of glomerular filtration rate in children. Pediatr Res. 2009 Jan;65(1):113-6. doi: 10.1203/PDR.0b013e318189a6e8. PMID: 18703997.
- Schwartz GJ, Muñoz A, Schneider MF, Mak RH, Kaskel F, Warady BA, Furth SL. New equations to estimate GFR in children with CKD. J Am Soc Nephrol. 2009 Mar;20(3):629-37. doi: 10.1681/ASN.2008030287. Epub 2009 Jan 21. PMID: 19158356; PMCID: PMC2653687.
As mentioned above
Schwartz use diffrent values of K constant acc to age group
Schwarzwald bedside use diffrent laboratory method to be used more suitable for globalisation and all population using constant K for all age gp
But I will add 2 Imp home message in this topic:
1st: before choose whic equation you will use in your institution ,you should ask you laboratory physician to know which type used in analysis for s.cr and ask him about it to determine using schwartz or schwartz bedside equation in ur hospital?
2nd: you should know that results from the 2 equations is repesent GFR acc. to BSA(body surface area) ,so before revise ur medication monograph you should know which mentioned in monograph GFR or cr.cl
So if cr cl
You should multiply the result by 1.73 BSA.
