Delay in separating blood samples affects creatinine measurement using the Roche kinetic Jaffe method.

Author(s): Ford L, Berg J

Publication: Ann Clin Biochem, 2008, Vol. 45, Page 83-7

PubMed ID: 18275679 PubMed Review Paper? No

Purpose of Paper

Conclusion of Paper

Studies

1. Study Purpose

   The purpose of this study was to investigate the effects on creatinine measurement of storage of clotted blood or serum at room temperature for up to 48 h. Once specimens had been serum separated and/or incubated at room temperature they were stored at -20 degrees C prior to measurement with the Roche creatinine kinetic Jaffe method.

   Summary of Findings:

   Specimens stored at room temperature prior to serum separation had significantly increased creatinine levels by 16 h (p<0.001). After storage of clotted blood for 48 h at room temperature, measured creatinine levels were an average of 29% higher than in specimens in which the serum was separated after 30 minutes at room temperature. While all specimens showed a significant increase, the magnitude was highly variable between individuals. The increased measured creatinine levels would result in changed kidney disease staging in 4 of 10 specimens by 16 h and 7 of 10 by 48 h. In contrast, storage of specimens at room temperature after serum separation did not cause an increase in measured creatinine by the Jaffe method.

   Biospecimens

   • Bodily Fluid - Blood
   • Bodily Fluid - Serum

   Preservative Types

   • Frozen

   Diagnoses:

   • Other diagnoses

   Platform:

   Analyte	Technology Platform
   Small molecule	Clinical chemistry/auto analyzer

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Preaquisition	Diagnosis/ patient condition	Kidney disease
   Storage	Time at room temperature	30 minutes 4 h 8 h 16 h 24 h 36 h 48 h
   Storage	Storage temperature	-20 degree C
   Biospecimen Aliquots and Components	Blood and blood products	Serum Whole blood
   Biospecimen Aliquots and Components	Centrifugation	Centrifugation delays investigated

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2. Study Purpose

   The purpose of this study was to investigate the effects of storage of clotted blood for 24 h at room temperature on measured creatinine levels and on the resultant eGFR and disease staging. Creatinine levels were measured by the Roche creatinine kinetic Jaffe method on a vertical P analyzer and the creatinine enzymatic method on a VITROS5 analyzer. All 113 specimens were stored at -20 degrees C prior to analysis.

   Summary of Findings:

   Creatinine levels measured with the Jaffe method increased by approximately 11% (p<0.0004) after storage for 24 h at room temperature and consequently the calculated eGFR decreased (P<0.0001). The increased creatinine levels resulted in changed kidney disease staging in 32% of cases. 26% of these cases went from stage 1 to stage 2 and 6% went from stage 2 to stage 3. Although creatinine levels were higher to begin with in men than woman, no effect of gender or ethnicity was found on the increase in creatinine measurement. The magnitude of the increase in measured creatinine with the Jaffe method was highly variable between individuals. The 10 specimens in which the largest change was observed using the Jaffe method were reanalyzed using the enzymatic method. Very little change (2.7% decrease) was observed in the measured creatinine levels using the enzymatic method when compared to baseline levels. In conclusion, storage of unseparated blood for 24h at room temperature caused an increase in measured creatinine by the Jaffe, but not the enzymatic method.

   Biospecimens

   • Bodily Fluid - Blood

   Preservative Types

   • Frozen

   Diagnoses:

   • Other diagnoses

   Platform:

   Analyte	Technology Platform
   Small molecule	Clinical chemistry/auto analyzer

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Storage	Time at room temperature	30 minutes 24 h
   Storage	Storage temperature	-20 degrees C
   Preaquisition	Patient gender	Female Male
   Preaquisition	Diagnosis/ patient condition	Kidney disease
   Clinical chemistry/auto analyzer Specific	Technology platform	Creatinine enzymatic method on a VITROS5 analyzer Roche creatinine kinetic Jaffe method on a vertical P analyzer
   Biospecimen Aliquots and Components	Centrifugation	Centrifugation delays investigated

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