RE: Schwartz formulae
Hi Mahesh
In addition to those papers presented by Samer, the following paper is also
likely to be very useful, and has good biological basis.
Human renal function maturation: a quantitative description using weight and
postmenstrual age.
Rhodin MM, Anderson BJ, Peters AM, Coulthard MG, Wilkins B, Cole M, Chatelut E,
Grubb A, Veal GJ, Keir MJ, Holford NH. Pediatr Nephrol. 2009 Jan;24(1):67-76.
Epub 2008 Oct 10.
Best wishes
Carl
Quoted reply history
-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of Mouksassi Mohamad-Samer
Sent: Wednesday, 1 April 2009 12:10 PM
To: Samtani, Mahesh [PRDUS]; [email protected]
Subject: RE: [NMusers] Schwartz formulae
Dear Mahesh,
As any model the original equation of Schwartz is evolving over the years and
as more data is gathered.
The original paper had only one k :
Schwartz GJ, Haycock GB, Edelmann CM Jr, Spitzer A. A simple estimate of
glomerular filtration rate in children derived from body length and plasma
creatinine. Pediatrics 1976; 58:259-263.
Then it was extended to other age groups to account for the maturational
changes:
Schwartz GJ, Brion LP, Spitzer A. The use of plasma creatinine concentration
for estimating glomerular filtration rate in infants, children, and
adolescents. Pediatr Clin North Am 1987; 34:571-590.
Then other papers suggested different adjustment to the original formula... and
to make it applicable for other age groups.
Please also note that the original k are applicable only for the old/standard
Jaffe method to measure serum creatinine.
Newer methods require some adjustments.
Newer formulas are now published using cystatin and other markers.
Zappitelli M, Parvex P, Joseph L, et al. Derivation and validation of cystatin
C-based prediction equations for GFR in children. Am J Kidney Dis 2006;
48:221-230
(standard Schwartz formula may be misleading when we have renal impairment)
New equations to estimate GFR in children with CKD.
Schwartz GJ, Muñoz A, Schneider MF, Mak RH, Kaskel F, Warady BA, Furth SL.
J Am Soc Nephrol. 2009 Mar;20(3):629-37. Epub 2009 Jan 21.
Estimating and measuring glomerular filtration rate in children.
Work DF, Schwartz GJ.
Curr Opin Nephrol Hypertens. 2008 May;17(3):320-5. Review.
The right formula will depend on the nature of your pediatric population you
want to calculate CRCL for , the method used for serum creatinine and whether
you have some renally impaired children or not.
Hope this helps
Samer
-----Original Message-----
From: [email protected] on behalf of Samtani, Mahesh [PRDUS]
Sent: Tue 3/31/2009 16:09
To: [email protected]
Subject: [NMusers] Schwartz formulae
Dear NMusers,
I am having difficulty with the Schwartz formulae for computing GFR in kids.
Some references state that the formula gives GFR in mL/min while others say it
is mL/min/1.73 m². Also the value of k varies between references. This is what
I plan on using. Are these formulas in the right units with the correct
constants.
Please advise,
Mahesh
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Schwartz formula:
GFR (mL/min/1.73 m²) = k*Height(cm) / Serum Creatinine (mg/dL)
k = 0.33 in Preterm Infants
k = 0.45 in Term infants to 1 year old
k = 0.55 for children aged 2 to 12 years
k = 0.55 for girls 13 to 21 years, and
k = 0.70 for boys 13 to 21 years
GFR corrected for the child's actual BSA, which can be obtained using the
DuBois and DuBois formula
GFR corrected = [GFR * 1.73] / BSA
The DuBois and DuBois formula:
BSA (m²) = (Weight^0.425 x Height^0.725) x 0.007184
where the weight is in kilograms and the height is in centimeters.
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