The Effect of Storing Temperature and Duration on Urinary Hydration Markers.
Author(s): Adams JD, Kavouras SA, Johnson EC, Jansen LT, Capitan-Jimenez C, Robillard JI, Mauromoustakos A
Publication: Int J Sport Nutr Exerc Metab, 2016, Vol. , Page 1-20
PubMed ID: 27616716 PubMed Review Paper? No
Purpose of Paper
This paper investigated the effects of storing urine for up to seven days at room temperature, 7, -20 or -80˚C and the effects of vortexing or centrifugation before analysis on the osmolality, specific gravity, and color of urine specimens from healthy individuals.
Conclusion of Paper
Urine stored at room temperature had comparable specific gravity to immediately analyzed specimens but higher osmolality when stored for two days and vortexed before analysis or stored seven days and vortexed or centrifuged and had lower color regardless of storage duration. . Storage of urine at 7˚C regardless of duration or centrifugation resulted in decreased color, but did not affect the osmolality or specific gravity of the urine. Urine stored at -20˚C had decreased osmolality and color for all storage durations and whether centrifuged or not and reduced specific gravity when stored for two or seven days, regardless of centrifugation. Similarly, urine stored at -80˚C had decreased color and specific gravity, regardless of storage duration and centrifugation, and decreased osmolality when stored one, two or seven days before vortexing or one or seven days before centrifugation.
Studies
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Study Purpose
This study investigated the effects of storing urine for 1, 2, or 7 days at room temperature, 7, -20 or -80˚C rather than analysis within 2 h and examined the effects of vortexing or centrifugation before analysis on the osmolality, specific gravity, and color of urine specimens from 36 healthy individuals. Urine was analyzed within 2 h and stored at 22°C (room temperature), 7°C, -20°C, and -80°C for 24 h, 48 h and 7 days before vortexing for 5 sec or centrifugation at 17,000 x g for 10 min before analysis. Osmolality was determined by freezing point depression using an Advanced Instruments 3250 osmometer, urine specific gravity was determined using an optical refractometer, and color was assigned by number using a color chart.
Summary of Findings:
Compared to immediately analyzed and vortexed specimens, osmolality was increased when urine was stored at room temperature for two (P=0.044) or seven days (P<0.001), decreased when stored for one, two, or seven days at -20˚C (P=0.002, P<0.001, and P<0.001; respectively) or -80˚C (P=0.02, P<0.001, and P<0.001; respectively), and was unaffected by storage at 7˚C before vortexing. Similar results were observed in specimens centrifuged after storage, but the effects of storage at room temperature or -80˚C for two days were no longer significant.
Urine specific gravity was unaffected by storage for up to seven days at room temperature or 7˚C but declined when stored at -20˚C for two or seven days (P<0.001, both) or -80˚C for one, two or seven days (P<0.001, all), regardless of whether specimens were centrifuged or vortexed before analysis.
Urinary color was significantly decreased from levels in fresh specimens after storage, regardless of duration, temperature, or whether centrifuged or vortexed.
Biospecimens
Preservative Types
- None (Fresh)
Diagnoses:
- Normal
Platform:
Analyte Technology Platform Small molecule Clinical chemistry/auto analyzer Morphology Macroscopic observation Electrolyte/Metal Clinical chemistry/auto analyzer Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Biospecimen Aliquots and Components Centrifugation Centrifuged
Not centrifuged
Storage Storage duration 2 h
1 day
2 days
7 days
Storage Storage temperature 22°C
7°C
-20°C
-80°C