Evaluation of the appropriate time period between sampling and analyzing for automated urinalysis.
Author(s): Dolscheid-Pommerich RC, Klarmann-Schulz U, Conrad R, Stoffel-Wagner B, Zur B
Publication: Biochem Med (Zagreb), 2016, Vol. 26, Page 82-9
PubMed ID: 26981022 PubMed Review Paper? No
Purpose of Paper
This paper investigated the effects of storage duration on urine particle and dipstick analysis.
Conclusion of Paper
Preanalytical storage of urine affected the white blood cell, red blood cell, epithelial cell, and cast counts and significantly affected the misclassification rate for measurement of pH, leukocytes, nitrite, protein, ketones, urobilinogen, blood, and specific gravity. There was no affect of storage for up to 240 min prior to analysis on bacterial cells counts or the misclassification rate for glucose or bilirubin.
Studies
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Study Purpose
This study investigated the effects of storage duration on urine particle counts. Urine from 321 patients were selected for inclusion based on containing more than 20 erythrocytes or leukocytes per μL or more than 100 bacteria per μL. Analysis was conducted using a Sysmex UF-1000i flow cytometer.
Summary of Findings:
Urine stored for 120 min or 240 min had significantly lower white blood cell counts (64 versus 72, P<0.001 and 57 versus 72, P<0.001, respectively), red blood cell counts (35 versus 39, P<0.001 and 27 versus 39, P<0.001, respectively), and casts (1 vs 1, P=0.009 and 1 versus 1, P<0.001, respectively) compared to urine analyzed within 90 min. Epithelial cell counts decreased when urine was stored for 240 min rather than less than 90 min (11 versus 11, P=0.041), but was not significantly different when stored for 120 min rather than less than 90 min. Conductivity was higher when specimens were stored for 120 or 240 min before analysis rather than less than 90 min (14.1 versus 14.0, P<0.001, and 14.8 versus 14.0, P<0.001). Bacterial counts were unaffected by preanalytical storage.
Biospecimens
Preservative Types
- None (Fresh)
Diagnoses:
- Other diagnoses
Platform:
Analyte Technology Platform Cell count/volume Flow cytometry Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Storage Time at room temperature <90 min
120 min
240 min
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Study Purpose
This study investigated the effects of storage duration on the misclassification rate for urine dipstick analysis. Urine from 321 patients were selected for inclusion based on containing more than 20 erythrocytes or leukocytes per μL or more than 100 bacteria per μL. Analysis was conducted using Combur-10-Teststrips on a Urisys2400.
Summary of Findings:
When urine was analyzed after 120 min or 240 min rather than 90 min, a significant increase was observed in the misclassification rate for the measurement of pH (P<0.001, both), leukocyte count (P<0.001, both), nitrite (P<0.001, both), protein (P<0.001, both), ketones (P<0.001, both), blood (P<0.001, both), and specific gravity (P<0.001, both). Misclassification of urobilinogen levels was significantly higher when specimens were stored for 120 min rather than 90 min (P=0.031), but not when stored for 240 min (P=0.125). Misclassification rates for glucose and bilirubin were unaffected by preanalytical storage.
Biospecimens
Preservative Types
- None (Fresh)
Diagnoses:
- Other diagnoses
Platform:
Analyte Technology Platform Carbohydrate Clinical chemistry/auto analyzer Small molecule Clinical chemistry/auto analyzer Protein Clinical chemistry/auto analyzer Cell count/volume Clinical chemistry/auto analyzer Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Storage Time at room temperature <90 min
120 min
240 min