Effect of long-term storage of urine samples on measurement of kidney injury molecule 1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL).
Author(s): van de Vrie M, Deegens JK, van der Vlag J, Hilbrands LB
Publication: Am J Kidney Dis, 2014, Vol. 63, Page 573-6
PubMed ID: 24268306 PubMed Review Paper? No
Purpose of Paper
This paper investigated the effects of addition of protease inhibitors prior to storage, storage at 4 or -80˚C, and post-storage centrifugation after thawing of frozen specimens on levels of neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule 1 (KIM-1) in urine from 39 kidney transplant patients.
Conclusion of Paper
KIM-1 levels declined significantly when urine was stored at 4˚C for 96 h (P<0.001) but NGAL levels were unaffected by storage at 4˚C, regardless of the addition of protease inhibitor cocktail. NGAL and KIM-1 levels in urine were unaffected by up to 6 months of storage at -80˚C, regardless of the addition of protease inhibitors or centrifugation prior to analysis.
Studies
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Study Purpose
This study investigated the effects of addition of protease inhibitors prior to storage, storage at 4 or -80˚C, and post-storage centrifugation after thawing of frozen specimens on levels of NGAL and KIM-1 in urine from 39 kidney transplant recipients. Second void urine was placed on ice until centrifugation for 10 min at 2000 x g and aliquoted. Protease inhibitor cocktail was added to half of the aliquots. Aliquots stored at 4˚C for 0, 48, or 96 h were vortexed before analysis. Aliquots stored at -80˚C for 0 h, 1 week, 1 month, 2 months, 4 months, or 6 months were thawed at room temperature and analyzed immediately or vortexed and centrifuged at 20,000 x g for 10 min before analysis. Levels of KIM-1 and NGAL were determined by ELISA.
Summary of Findings:
KIM-1 levels declined significantly when urine was stored at 4˚C for 96 h (P<0.001) but NGAL levels were unaffected by storage at 4˚C, regardless of the addition of protease inhibitor cocktail. NGAL and KIM-1 levels in urine were unaffected by up to 6 months of storage at -80˚C, regardless of the addition of protease inhibitors or centrifugation prior to analysis.
Biospecimens
Preservative Types
- None (Fresh)
- Frozen
Diagnoses:
- Other diagnoses
Platform:
Analyte Technology Platform Protein ELISA Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Biospecimen Preservation Type of fixation/preservation Frozen
None (fresh)
Refrigeration
Biospecimen Aliquots and Components Centrifugation Centrifuged
Not centrifuged
Analyte Extraction and Purification Protease inhibitor Cocktail
No protease inhibitor added
Storage Storage duration 0 h
48 h
96 h
1 week
1 month
2 months
4 months
6 months
Storage Storage temperature 4˚C
-80˚C