Quality assurance in the pre-analytical phase of human urine samples by (1)H NMR spectroscopy.
Author(s): Budde K, Gök ÖN, Pietzner M, Meisinger C, Leitzmann M, Nauck M, Köttgen A, Friedrich N
Publication: Arch Biochem Biophys, 2016, Vol. 589, Page 10-7
PubMed ID: 26264917 PubMed Review Paper? No
Purpose of Paper
This paper investigated the effects of storage on the metabolic profile of urine specimens.
Conclusion of Paper
The main source of disparity in the metabolic profile or urine was inter-subject variation. Storage at 4˚C for 60 min before centrifugation resulted in a slight increase in succinate levels, but pre-or post-centrifugation storage at 4˚C had no other effects. Increases in acetate and succinate and in an unknown triplet at ppm 4.04 were observed when samples were stored at 25˚C rather than 10˚C and peaks representing creatinine and ethanol were increased when stored for 24 h or more at room temperature. There were no effects of storing urine for one month at -80˚C.
Studies
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Study Purpose
The purpose of this study was to investigate the effects of pre and post-centrifugation refrigerated storage on the metabolic profile of urine. Midstream urine was collected from 11 individuals with estimated GFR below 70 ml/min/1.73 m2. Urine specimens were aliqouted and centrifuged immediately or after a 60 min delay at 4˚C. After centrifugation, specimens were frozen at -80˚C immediately or after 10 h at 4˚C. Frozen specimens were shipped before analysis.
Summary of Findings:
The main source of disparity in the metabolic profile or urine was inter-subject variation. Storage at 4˚C for 60 min before or 10 h after centrifugation did not alter the metabolic profile or affect levels of highly abundant metabolites. Qualitatively, there were no effects of refrigerated storage pre or post-centrifugation on low abundance peaks, but slightly higher levels of succinate were found in specimens stored at 4˚C for 60 min before centrifugation than when centrifuged immediately (P=0.02, regardless of post-centrifugation storage).
Biospecimens
Preservative Types
- Frozen
Diagnoses:
- Not specified
Platform:
Analyte Technology Platform Small molecule NMR Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Biospecimen Aliquots and Components Centrifugation Centrifugation delays investigated
Storage Storage conditions Centrifuged
Not centrifuged
Storage Storage duration 0 min
60 min
10 h
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Study Purpose
The purpose of this study was to investigate the effects of room temperature or refrigerated storage on the metabolic profile of urine. Midstream urine was collected in the morning (8-10 AM) from 11 healthy volunteers. Specimens were aliquoted for storage at 25˚C or in a NMR cooling rack (10˚C) for 0, 2, 4, 8, 12, 24, 48, or 72 h) with or without phosphate buffer. All specimens were mixed with phosphate buffer before NMR analysis.
Summary of Findings:
While storage time, temperature, and addition of phosphate buffer did not influence classification of urine specimens, individual signal peaks were affected. Larger increases in singlets at 1.925 and 2.41 (most likely acetate and succinate) and in an unknown triplet at ppm 4.04 were observed when samples were stored at 25˚C rather than 10˚C and peaks representing creatinine and ethanol were increased when stored for 24 h or more at room temperature. There was no effect of storing urine for one month at -80˚C.
Biospecimens
Preservative Types
- Frozen
- None (Fresh)
Diagnoses:
- Normal
Platform:
Analyte Technology Platform Small molecule NMR Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Storage Storage temperature 25˚C
10˚C
-80˚C
Biospecimen Preservation Type of fixation/preservation Frozen
None (fresh)
Refrigeration
Storage Storage conditions With phosphate buffer
Without phosphate buffer
Storage Storage duration 0 h
2 h
4 h
8 h
12 h
24 h
48 h
72 h