Pediatric Nephrology

, Volume 24, Issue 1, pp 113–119

Validation of creatinine assays utilizing HPLC and IDMS traceable standards in sera of children

  • George J. Schwartz
  • Tai Kwong
  • Brian Erway
  • Bradley Warady
  • Lori Sokoll
  • Stanley Hellerstein
  • Vikas Dharnidharka
  • Susan Furth
  • Alvaro Muñoz
Original Article

Abstract

The purpose of this study was to validate serum creatinine (SCr) concentrations assayed in the Central Biochemistry Laboratory of the National Institutes of Health (NIH)-funded Chronic Kidney Disease in Children (CKiD) study utilizing an enzymatic assay (Siemens Advia 2400) against a method traceable to reference isotope dilution mass spectroscopy (IDMS) developed by the National Institute of Standards and Technology (NIST). High-performance liquid chromatography (HPLC) measured SCr after external validation utilizing IDMS-based standard reference materials. Sera from the first 201 subjects enrolled in CKiD were analyzed and compared for creatinine concentration by enzymatic and HPLC methods. Fifty “normal” pediatric sera were subsequently analyzed. Finally, a “pediatric” reference standard was prepared and examined for accuracy and precision. Enzymatic SCr concentrations (median 1.4 mg/dl) of CKiD subjects were well correlated with HPLC (r = 0.984) but were slightly higher (+7%; p < 0.001). Agreement was poorer at lower SCr (median 0.4 mg/dl) when using samples from normal children and the “pediatric” reference standard. However, the Roche enzymatic assay was comparable with HPLC in accuracy and precision. Referring physicians should be aware of the accuracy and reproducibility of their laboratory’s SCr assay. Our enzymatic assay agreed well with HPLC in CKiD subjects with elevated SCr. We suggest that NIST develop a pediatric SCr standard reference material for use by assay manufacturers to improve accuracy and precision of assays at the low SCr levels observed in most pediatric patients.

Keywords

High-performance liquid chromatography Glomerular filtration rate Enzymatic creatinine assay Jaffe creatinine assay Isotope dilution mass spectroscopy Pediatric standards 

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Copyright information

© IPNA 2008

Authors and Affiliations

  • George J. Schwartz
    • 1
    • 6
  • Tai Kwong
    • 1
  • Brian Erway
    • 1
  • Bradley Warady
    • 2
  • Lori Sokoll
    • 3
  • Stanley Hellerstein
    • 2
  • Vikas Dharnidharka
    • 4
  • Susan Furth
    • 3
  • Alvaro Muñoz
    • 5
  1. 1.University of Rochester Medical CenterRochesterUSA
  2. 2.Children’s Mercy HospitalKansas CityUSA
  3. 3.Johns Hopkins Medical InstitutionsBaltimoreUSA
  4. 4.University of FloridaGainesvilleUSA
  5. 5.Johns Hopkins Bloomberg School of Public HealthBaltimoreUSA
  6. 6.Pediatric NephrologyUniversity of Rochester Medical CenterRochesterUSA

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