Preanalytical handling of stored urine samples, and measurement of beta 2-microglobulin, orosomucoid, albumin, transferrin and immunoglobulin G in urine by enzyme-linked immunosorbent assays (ELISA).
Author(s): Vittinghus E
Publication: Scand J Clin Lab Invest, 1990, Vol. 50, Page 843-9
PubMed ID: 2084821 PubMed Review Paper? No
Purpose of Paper
This paper investigated the effects of storage temperature, addition of surfactants (BSA, or Tween-20), thawing temperature, and post-thaw storage on levels of β2-microglobulin (B2M), orosomucoid, albumin, transferrin, and immunoglobulin G (IgG) in urine.
Conclusion of Paper
Levels of B2M, orosomucoid, albumin, transferrin, and IgG were stable in urine stored for one week at 4˚C or room temperature or stored at -20˚C in the presence of tween-20. Levels of IgG, transferrin, albumin, and B2M decreased when thawed at room temperature rather than in a 37˚C water bath, especially when stored at 4˚C post-thaw. Importantly, addition of tween-20 post-thaw attenuated the effects of storage at -20˚C.
Studies
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Study Purpose
This study investigated the effects of storage temperature and addition of surfactants (BSA, or Tween-20) on levels of β2-microglobulin (B2M), orosomucoid, albumin, transferrin, and immunoglobulin G (IgG) in thimeresol-preserved urine from six healthy men. Overnight urine was aliquoted and thimeresol, with or without tween-20, or BSA was added. The aliquots were then subjected to one week of storage at -20˚C, 4˚C, or room temperature. To investigate the effects of adsorption, urine was decanted four times at 24 h intervals into a new tube, analyzed, and stored at 4˚C. Importantly, all aliquots were brought to room temperature before analysis.
Summary of Findings:
The authors state that there was no effect of storing urine at room temperature or 4˚C on levels of B2M, orosomucoid, albumin, transferrin, or IgG, regardless of the addition of thimersol, with or without tween-20, or BSA. In contrast, levels of albumin, IgG, and tranferrin but not orosomucoid and B2M declined after a week of storage of urine at -20˚C in the absence of tween-20. The largest decreases in albumin (11%), IgG (21%), and transferrin (57%) occurred when urine was stored at -20˚C without an additive, followed by urine stored with BSA. Importantly, addition of tween-20 after thawing restored levels of albumin, IgG, and transferrin to initial levels. The authors report no effect of adsorption as levels of analytes were not affected by decanting into a new tube every 24 h, regardless of additive.
Biospecimens
Preservative Types
- Frozen
- Other Preservative
Diagnoses:
- Normal
Platform:
Analyte Technology Platform Protein ELISA Glycoprotein ELISA Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Storage Storage temperature -20˚C
4˚C
Room temperature
Biospecimen Preservation Fixative additive/buffer Tween20
BSA
None
Storage Storage conditions One container
Decanted between containers
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Study Purpose
The purpose of this study was to investigate the effects of thawing temperature, post-thaw storage temperature and duration, and the addition of tween-20 on levels of B2M, orosomucoid, albumin, transferrin, and IgG in urine from 13 patients with Type I diabetes. Urine was collected during exercise tests, BSA was added, and the specimens were stored at -20˚C for years. Urine from five of the diabetic patients was thawed by incubation in a 37˚C water bath for one hour or by storage at room temperature. After thawing, tween-20 was added and specimens were stored at room temperature or 4˚C (room temperature-thawed only) for 0, 1, 10, and 22 days. Urine from the other eight diabetic patients was stored at -20˚C for more than 2 years and thawed in a 37˚C water bath for 30 min, tween-20 was added, and specimens were stored at room temperature for 1 or 35 days.
Summary of Findings:
Protein levels remained within 20% when thawed in a 37˚C water bath and stored at room temperature for 22 days. Larger decreases occurred when urine was thawed at room temperature, especially when stored at 4˚C after thawing. Specimens thawed at room temperature and stored at 4˚C had decreased levels of IgG (47%), transferrin (61%), albumin (26%,) and B2M (18%) compared to specimens thawed at 37˚C and stored at room temperature, but orosomucoid levels were comparable. Protein levels in specimens stored for 2 years at -20˚C, thawed at 37˚C, and treated with Tween-20 were comparable when measured the day after thawing and 35 days later.
Biospecimens
Preservative Types
- Frozen
Diagnoses:
- Diabetes Type 1
Platform:
Analyte Technology Platform Glycoprotein ELISA Protein ELISA Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Storage Thaw temperature/condition Room temperature
37˚C water bath
Storage Post-thaw duration 0 days
1 day
10 days
22 days
35 days