Cancer Diagnosis Program | Biorepositories and Biospecimen Research Branch

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Urine stability studies for novel biomarkers of acute kidney injury.

Author(s): Parikh CR, Butrymowicz I, Yu A, Chinchilli VM, Park M, Hsu CY, Reeves WB, Devarajan P, Kimmel PL, Siew ED, Liu KD

Publication: Am J Kidney Dis, 2014, Vol. 63, Page 567-72

PubMed ID: 24200462 PubMed Review Paper? No

Purpose of Paper

Conclusion of Paper

Studies

1. Study Purpose

   This study compared levels of five biomarkers in urine that was frozen immediately after centrifugation and urine that was not centrifuged or stored at 4 or 25˚C for 48 h before freezing. Urine was collected from 52 patients within 48 h of cardiac surgery at the Yale New Haven hospital and after admission to the University of California San Francisco hospital’s intensive care unit admission from 36 patients admitted from the emergency room or due to congestive heart failure. Specimens were obtained by Foley catheter or were voided clean catch urine. Immediately following collection, urine specimens were aliquoted and 1)immediately centrifuged at 1000 x g at 4˚C for 10 min, and then frozen 2) centrifuged at 1000 x g at 4˚C for 10 min and then stored at 4˚C for 48 h before freezing, or 3) centrifuged at 1000 x g at 4˚C for 10 min and stored at room temperature for 48 h before freezing, or 4) left uncentrifuged and frozen. Frozen specimens were stored at -80˚C for a median of 5 months. IL-18, NGAL, L-FABP, and KIM-1 were determined by ELISA, creatinine levels were determined by the Jaffe method, and cystatin C was determined using a nephelometric immunoassay.

   Summary of Findings:

   Levels of NGAL, KIM-1, L-FABP, and cystatin C were very strongly correlated among specimens that were centrifuged and immediately frozen and specimens that were not centrifuged (r=0.99, all) or were centrifuged and stored for 48 h at room temperature (r=0.99, r=0.99, r=0.95, and r=0.93, respectively) or 4˚C (r=0.99, r=0.99, r=0.99, and r=0.94, respectively) before freezing.  Correlation in levels of NGAL, KIM-1, L-FABP, and cystatin C among the different processing regimes were similar regardless of whether specimens below the LLD were included or not. IL-18 levels above the LLD were very strongly correlated among specimens centrifuged and immediately frozen and specimens that were not centrifuged (r=0.98) or were stored at 4˚C for 48 h before freezing (r=0.92) and strongly correlated among centrifuged specimens that were immediately frozen and those that were stored for 48 h at room temperature (r=0.81). When levels below the LLD were included in the analysis, the correlations in IL-18 levels among specimens subjected to post-centrifugation storage at 4 or 25˚C were 0.83 and 0.68, respectively. There was no association between levels of IL-18, NGAL, KIM-1, L-FABP, and cystatin C and lack of centrifugation or post-centrifugation storage at 4˚C. The authors report no effect of the use of Foley catheter to collect urine or the diagnosis of diabetes on the measurement of IL-18, NGAL, KIM-1, L-FABP and cystatin C.

   Biospecimens

   • Bodily Fluid - Urine

   Preservative Types

   • Frozen

   Diagnoses:

   • Diabetes Type 1
   • Diabetes Type 2
   • Other diagnoses
   • Not specified
   • Cardiovascular Disease

   Platform:

   Analyte	Technology Platform
   Protein	ELISA
   Small molecule	Clinical chemistry/auto analyzer
   Protein	Immunoassay

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Biospecimen Acquisition	Method of fluid acquisition	Catheterized urine Voided urine (spot collection)
   Preaquisition	Diagnosis/ patient condition	Diabetic Non-diabetic
   Storage	Storage temperature	4˚C Room temperature
   Storage	Storage duration	0 h 48 h
   Biospecimen Aliquots and Components	Centrifugation	Centrifuged Not centrifuged

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