Collection and storage requirements for urinary kidney injury molecule-1 (KIM-1) measurements in humans.
Author(s): Pennemans V, Rigo JM, Penders J, Swennen Q
Publication: Clin Chem Lab Med, 2011, Vol. 50, Page 539-43
PubMed ID: 22107138 PubMed Review Paper? No
Purpose of Paper
This paper investigated the effect of centrifugation, sedimentation, addition of protease inhibitors, storage duration, freeze-thaw cycling, and thaw duration on levels of KIM-1 in urine specimens.
Conclusion of Paper
KIM-1 levels were significantly higher when specimens were stored at room temperature for 24 h or more before freezing, thawed for 3 h or more, or stored at 4˚C for 3 weeks or more. KIM-1 levels in urine declined with freeze-thaw cycling or storage at -20˚C but were not affected by long-term storage at -80˚C, the addition of protease inhibitors, centrifugation or sedimentation before freezing.
Studies
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Study Purpose
This study investigated the effects of centrifugation, sedimentation, addition of protease inhibitors, room temperature storage, and thaw duration on levels of KIM-1 in urine specimens. Second morning urine from 20 healthy individuals (9 men, 11 women) was adjusted to a pH of 6-8 and aliquoted into 13 specimens. Five aliquots were frozen immediately at -80˚C, one was treated with protease inhibitors before freezing, one was allowed to sediment for an hour before the supernatant was frozen, one was centrifuged at 2554 x g for 5 min and the supernatant frozen, and the remaining aliquots were stored at room temperature for 1, 3, 24, and 48 h before freezing.
Summary of Findings:
KIM-1 levels in urine were not affected by the addition of protease inhibitors, centrifugation, or sedimentation before freezing. KIM-1 levels increased to 122.3% and 134.7% of initial levels when specimens were stored at room temperature for 24 h and 48 h before freezing, respectively (P=0.007 and P=0.0002, respectively), but the increase was not significant when the specimens were stored for 1 or 3 h. KIM-1 levels were significantly higher when thaw time was increased from 1 h to 3 h (125%, P=0.003) or 24 h (152%, P=0.0002, respectively).
Biospecimens
Preservative Types
- Frozen
Diagnoses:
- Normal
Platform:
Analyte Technology Platform Protein ELISA Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Storage Post-thaw duration 1 h
3 h
24 h
Storage Storage duration 0 h
1 h
3 h
24 h
48 h
Analyte Extraction and Purification Protease inhibitor Cocktail
No protease inhibitor added
Biospecimen Aliquots and Components Centrifugation Centrifuged
Not centrifuged
Storage Time at room temperature 0 h
1 h
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Study Purpose
This study investigated the effects of creatinine levels; storage at 4, -20, and -80˚C; and freeze-thaw cycling on levels of KIM-1 in urine specimens. Second morning urine from 30 healthy individuals (7 men, 23 women) was adjusted to a pH of 6-8 and aliquoted into eight specimens. One aliquot was analyzed for KIM-1 within 4 h of collection, another was analyzed for creatinine within 4 h, one aliquot was stored at -20˚C for 12 weeks, one was stored at -80˚C for 12 weeks, and the remaining aliquots were stored at 4, -20, or -80˚C and each aliquot was analyzed after 24 h, 1 week, 3 weeks, 7 weeks, and 12 weeks of storage (1-5 freeze-thaw cycles).
Summary of Findings:
With each freeze-thaw cycle, levels of KIM-1 declined by 10% with a slightly faster decline noted when frozen at -20˚C rather than -80˚C. The percentage recovery after 12 weeks at -20˚C was 78.58% when not freeze-thaw cycled and 69.37% when freeze-thaw cycled 5 times. The percentage recovery after 12 weeks at -80˚C was 96.52% when not freeze-thaw cycled and 78.44% when freeze-thaw cycled 5 times. Although 89.6% of KIM-1 was recovered after 24 h at 4˚C, 98.96% was recovered after 1 week and 127.4% was recovered after 12 weeks. The authors report no effect of creatinine levels on the percentage KIM-1 recovery.
Biospecimens
Preservative Types
- None (Fresh)
- Frozen
Diagnoses:
- Normal
Platform:
Analyte Technology Platform Small molecule Clinical chemistry/auto analyzer Protein ELISA Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Storage Storage temperature 4˚C
-20˚C
-80˚C
Storage Freeze/thaw cycling 1 cycle
2 cycles
3 cycles
4 cycles
5 cycles
Storage Storage duration <4 h
24 h
1 week
3 weeks
7 weeks
12 weeks
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Study Purpose
This study investigated the effects of 19-22 months of storage at -80˚C on levels of KIM-1 in urine. Second morning urine from 126 healthy individuals (7 men, 23 women) was adjusted to a pH of 6-8 and frozen at -80˚C within 4 h of collection. KIM-1 was analyzed within two months and again after 19-22 months.
Summary of Findings:
After storage for 19-22 months at -80˚C, KIM-1 levels were comparable to those in specimens stored for less than two months.
Biospecimens
Preservative Types
- Frozen
Diagnoses:
- Normal
Platform:
Analyte Technology Platform Protein ELISA Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Storage Storage duration <2 months
19-22 months