Impact of different preservation methods on urinary red blood cell counts.
Author(s): Nonkes L, Yaz Aydın G, Van't Hof M, Demir AY
Publication: Clin Chem Lab Med, 2023, Vol. , Page
PubMed ID: 37883021 PubMed Review Paper? No
Purpose of Paper
This paper compared the stability of red blood cell (RBC) counts in matched aliquots of urine stored at 4°C for up to 24 h in BD Vacutainer Urinalysis tubes with or without an additive, Greiner VACUETTE Stabilur Tubes containing mercuric salt-based particles, and in tubes prefilled with BD CellFIX or glutaraldehyde.
Conclusion of Paper
ANOVA analysis identified significant effects of storage duration and preservation on RBC count and an interaction between storage duration and preservation. In all tube types, the RBC count declined with storage, but the largest decline in RBC counts occurred when the urine was not preserved; the smallest changes in RBC counts with storage were observed in urine preserved with glutaraldehyde. There was a significant difference between RBCs in unpreserved urine and urine preserved with glutaraldehyde, but no other significant differences were identified from pairwise comparisons.
Studies
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Study Purpose
This study compared the stability of RBC counts in matched aliquots of urine stored at 4°C for up to 24 h in BD Vacutainer Urinalysis tubes with or without an additive, Greiner VACUETTE Stabilur Tubes containing mercuric salt-based particles, and in tubes prefilled with BD CellFIX or glutaraldehyde. Leftover unpreserved urine from eight patients with hematuria were transferred to BD Vacutainer Urinalysis Tubes (no preservative), BD Vacutainer Urinalysis Tubes with an additive (spray-coated with 0.4% chlorhexidine, 5.6% ethylparaben, and 94% sodium propionate), Greiner VACUETTE Stabilur Tubes containing mercuric salt-based particles, tubes prefilled with BD CellFIX (10% formaldehyde, 3.55% methanol, 0.93% sodium azide), tubes prefilled with glutaraldehyde to achieve a final glutaraldehyde concentration of 0.06%, and tubes prefilled with glutaraldehyde to achieve a final glutaraldehyde concentration of 0.1. All tubes were placed on a rotator for 15 min before storage at 4°C for 0, 2, 4, 6, and 24h. At each timepoint, urine was mixed by aspiration and an aliquot was centrifuged at 200 g for 10 sec, the sediment was visualized using a digital microscope, and images were analyzed using an automated method as well as by two technicians. Red blood cells were enumerated using an Atellica UAS 800 automated urine sediment analyzer.
Summary of Findings:
The average RBC count in urine specimens prior to storage was 1194 RBCs per µL. ANOVA analysis identified significant effects of storage duration (p<0.0005) and preservation (p<0.0005) on RBC count and an interaction between storage duration and preservation (p<0.0005). In all tube types, RBC count declined with storage, but the largest decline in RBC counts occurred when the urine was not preserved (~60% decrease after 24 h). The smallest changes in RBC counts with storage were observed in urine preserved with glutaraldehyde (less than 20% decrease after 24 h). While there was a significant difference in RBC in unpreserved urine and urine preserved with glutaraldehyde (p<0.05 for both glutaraldehyde concentrations), no other significant differences were identified from pairwise comparisons.
Biospecimens
Preservative Types
- Other Preservative
- None (Fresh)
Diagnoses:
- Other diagnoses
Platform:
Analyte Technology Platform Cell count/volume Light microscopy Cell count/volume Hematology/ auto analyzer Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Biospecimen Preservation Type of fixation/preservation Glutaraldehyde
Formaldehyde
Mercuric salt
None (fresh)
Chlorhexadine
Ethylparaben
Sodium propionate
Storage Storage duration 0 h
2 h
4 h
6 h
24 h
Biospecimen Preservation Concentration of fixative 0.06% Glutaraldehyde
0.1% Glutaraldehyde