Urine transfer devices may impact urinary particle results: a pre-analytical study.
Author(s): Debunne N, Delanghe J, Raman L, Oyaert M
Publication: Clin Chem Lab Med, 2023, Vol. , Page
PubMed ID: 37340894 PubMed Review Paper? No
Purpose of Paper
This paper compared urine test strip results and red blood cell (RBC), white blood cell (WBC), renal tubular epithelial cell (RTEC), bacterial cell, hyaline cast, pathological cast, and crystal counts in urine specimens transported in the original container with those that were transported in transfer tubes and placed in new containers before analysis.
Conclusion of Paper
When urine specimens transported in the original container (control, International Medical Products Collection Container) and urine transported in four different transfer tubes were compared, the kappa agreement score was ≥0.81 for all eleven analytes analyzed via urine test strips. Urine that was transported in either BD Plus Urine Tubes (BD, transferred using BD Vacutainer Urine Collection Cup) or Greiner Z Urine Tubes (transferred in Deltalab Tubes) had higher mean RBC counts than urine that was transported in the original collection containers, although the increases observed in all specimens were below the threshold for clinical significance. RBC counts were associated with the presence of RTEC in urine in BD, Greiner, and Sarstedt Urine Monovette transfer tubes (Sarstedt aspiration tube, transported in Sarstedt Containers with Screw Cap). In urine specimens that contained pathological casts, the average RBC count was significantly higher than in specimens in the same tube type that did not contain casts. Specific hemoglobin peroxidase activity was lower in urine specimens transported in BD, Greiner, Sarstedt aspiration and Sarstedt V-Monovette (vacuum, transported in Sarstedt Containers with Screw Cap) tubes than the control tube, which the authors state is the result of vacuum/aspiration on RBC membrane integrity. Mean RTEC counts were lower in urine specimens that were transported in BD and Greiner tubes compared to the control tube, but there was a high degree of variation. Importantly, a false negative for the presence of RTECs in the control specimen was observed for 16 of 40 specimens transported in BD or Greiner tubes, 12 of 40 specimens transported in Sarstedt vacuum tubes, and 11 of 40 specimens transported in Sarstedt aspiration tubes. Bacterial counts were significantly higher in urine specimens that were transferred to a transfer tube all four tube types relative to the control specimen (which was not transferred prior to transport). Fewer hyaline casts were found in urine specimens transported in either BD or Greiner tubes relative to control specimens, although the agreement between these tube types and the control specimen was still >95%. Fewer pathological casts were found in urine specimens transported in the BD, Griner, and Sarstedt vacuum tubes relative to control specimens. Importantly, of the 133 urine specimens that tested positive for pathological casts, 3 to 7 were misclassified as negative in specimens that were transported in a transfer tube. The loss of pathological casts in urine specimens that were transported in a transfer tube was associated with osmolality. WBC and crystal counts were comparable in urine specimens regardless of whether the specimen was transferred prior to transport and the type of transfer tube used.
Studies
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Study Purpose
This study compared urine test strip results and RBC, WBC, RTEC, bacterial cell, hyaline cast, pathological cast, and crystal counts in urine specimens transported in the original container and those transported in transfer tubes and placed in new containers before analysis. Urine was collected from 146 patients (0-99 years of age; 73 males and 73 females). The first 50 specimens were randomly selected and the following 96 were selected based on the presence of WBC (≥ 25 × 106/L required), RBC (≥ 25 × 106/L required), RTEC (≥3 × 106/L required), casts (≥1 × 106/L required) or crystals (≥ 10 × 106/L required). Urine was collected into International Medical Products Collection Containers, and divided and transferred into the following three transfer containers: Deltalab Containers for Vacuum Tubes (Greiner), BD Vacutainer Urine Collection Cups (BD) and Sarstedt Containers with Screw Cap. Urine specimens were then transported to the laboratory (duration and conditions of transport not specified). Upon arrival, urine was transferred from Deltalab Containers to Greiner Z Urine Tubes, from the BD Vacutainers to BD Plus Urine Tubes, and from Sarstedt Collection Containers into Sarstedt Urine Monovette (aspiration) and V-Monovette (vacuum) Urine Transfer Tubes prior to analysis. Urine that was kept in the original container and was not transferred served as the control. Levels of albumin, bilirubin, creatinine, glucose, hemoglobin, ketones, leukocytes, nitrite, pH, protein and urobilinogen were quantified using Meditape UC-11A test strips and a test strip analyzer UC-3500 instrument. Cells and particles were counted using a Sysmex UF-5000 analyzer.
Summary of Findings:
When urine that was transported in the original container (control) and urine transferred into four different transfer tubes prior to transport were compared, the kappa agreement score was ≥0.81 for all eleven analytes analyzed via urine test strips. Urine transferred and transported in BD tubes and Greiner tubes had higher mean RBC counts than urine that was transported in the original containers (9% and 13%, respectively); however, the observed increases were below the level for clinical significance in all specimens (50%). For the same tube type, the average RBC count was significantly higher in urine specimens with pathological casts than those without without casts (P=0.016 in BD tubes, P<0.001 in Greiner tubes, P=0.059 in Sarstedt vacuum tubes, and P=0.018 in Sarstedt aspiration tubes). RBC counts were associated with the presence of RTEC in urine transferred to BD tubes (p=0.036), Greiner tubes (p=0.023), and Sarstedt aspiration tubes (p=0.007), and there was a trend toward an association of RBC counts with pH in urine transferred to Greiner (p=0.12) and Sarstedt vacuum (P=0.02) tubes. Specific hemoglobin peroxidase activity was lower in urine transferred to BD, Greiner, and Sarstedt tubes than the control tube, which the authors state is the result of vacuum/aspiration on RBC membrane integrity. Mean RTEC counts were lower in urine transferred to BD and Greiner tubes than in the control tube (P=0.015 and P=0.003, respectively), but there was a high degree of variation. Importantly, false negatives for the presence of RTECs relative to the control were found for 16 of 40 urine specimens transferred to BD or Greiner tubes (κ=0.61 and 0.57, respectively), 12 of 40 specimens (κ=0.69) transferred to Sarstedt vacuum tubes, and 11 of 40 specimens (κ=0.73) transferred to Sarstedt aspiration tubes. Bacterial cell counts were significantly higher in urine transferred to BD, Greiner, Sarstedt vacuum, and Sarstedt aspiration tubes than the control urine specimen (P<0.001, P<0.001, P<0.00 and P<0.004, respectively). Fewer hyaline casts were found in urine specimens in the control transferred to BD and Greiner tubes than control specimens (P=0.024 and P=0.025, respectively); however, agreement with the control specimen remained >95%. Fewer pathological casts were found in urine specimens transferred to BD, Griner, and Sarstedt vacuum tubes than control specimens that were not transferred (P=0.001, P=0.004, and P=0.001, respectively). Importantly, of the 133 urine specimens that tested positive for pathological casts, 3 to 7 were misclassified as negative in specimens that were transported in a transfer tube. The loss of pathological casts was associated with osmolality, and the largest effect was seen in urine transferred to BD tubes (P=0.02). WBC and crystal counts were comparable among urine transported in different tube types.
Biospecimens
Preservative Types
- None (Fresh)
Diagnoses:
- Not specified
Platform:
Analyte Technology Platform Carbohydrate Clinical chemistry/auto analyzer Cell count/volume Clinical chemistry/auto analyzer Small molecule Clinical chemistry/auto analyzer Protein Clinical chemistry/auto analyzer Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Storage Storage conditions Control, International Medical Products Collection Container
Transferred using BD Vacutainer Urine Collection Cup into BD Plus Urine Tubes
Transferred using Deltalab Tubes into Greiner Z Urine Tubes
Transferred using Sarstedt Containers with Screw Cap into Sarstedt Urine Monovette (Aspiration) Tubes
Transferred using Sarstedt Containers with Screw Cap into Sarstedt Urine V-Monovette (Aspiration) Tubes
Storage Specimen transport duration/condition Transported in original collection container
Transferred to BD Vacutainer Urine Collection Cup for transport then into BD Plus Urine Tube
Transferred to Deltalab Tubes for transport then into Greiner Z Urine Tubes
Transferred to Sarstedt Containers with Screw Cap for transport then into Sarstedt Urine Monovette (Aspiration) Tubes
Transferred to Sarstedt Containers with Screw Cap for transport then into Sarstedt Urine V-Monovette (Vacuum) Tubes