Reference range of some enzymes and proteins in untimed overnight urine and their stability after freezing.
Author(s): Berg KJ, Kristoffersen DT, Djøseland O, Hartmann A, Breistein E, Lund KK, Narverud J, Nossen JO, Stenstrøm J
Publication: Clin Chim Acta, 1998, Vol. 272, Page 225-30
PubMed ID: 9641362 PubMed Review Paper? No
Purpose of Paper
This paper investigated the effects of patient age and frozen storage duration on the measurement of albumin, creatinine, N-acetyl-b-glucosaminidase (NAG), β2-microglobulin (B2M), and alkaline phosphatase (ALP) in urine.
Conclusion of Paper
Storage of urine at -20˚C resulted in significantly lower levels of ALP and NAG after 2 weeks and albumin after 2 months but did not affect the levels of B2M or creatinine. Levels of creatinine, NAG, B2M, and ALP were dependent on patient age but albumin levels were comparable regardless of patient age.
Studies
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Study Purpose
This study investigated the effects of patient age on the measurement of albumin, creatinine, NAG, β2M, and ALP in urine from 150 healthy patients. Urine was collected into polyvinyl cans and first analyzed within 8 h after centrifugation. Specimens for β2-microglobulin had the pH adjusted to 6.5-8.0 before analysis. Creatinine, NAG, and ALP levels were determined by a colorimetric assay on a clinical chemistry analyzer and albumin was determined using immunoturbidimetric method on a clinical chemistry analyzer.
Summary of Findings:
Compared to specimens from 20-to 34-year old patients, specimens from 35 to 49- and 50 to 69 -year old patients had lower levels of creatinine (15.682 versus 10.429 and 9.120, respectively, P<0.001 and P<0.0001), and higher levels of NAG (0.117 versus 0.137 and 0.184, respectively, P<0.01 and P<0.0001), and ALP (0.417 versus 0.552 and 0.573, respectively, P<0.01 and P<0.001). B2M levels also were higher in specimens from older patients than younger, but the effect was only significant when comparing specimens from 50 to 69 rather than 20 to 34-year old patients (8.337 versus 6.041, P<0.001). Albumin levels were not affected by patient age.
Biospecimens
Preservative Types
- None (Fresh)
Diagnoses:
- Normal
Platform:
Analyte Technology Platform Protein Clinical chemistry/auto analyzer Small molecule Colorimetric assay Protein Immunoturbidometric assay Protein Colorimetric assay Small molecule Clinical chemistry/auto analyzer Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Preaquisition Patient age 20-34 years
34-49 years
50-69 years
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Study Purpose
This study investigated the effects of frozen storage duration on the measurement of albumin, creatinine, NAG, β2M, and ALP in urine. Urine was collected into polyvinyl cans and first analyzed within 8 h after centrifugation. Urine was transferred to polypropylene tubes, frozen at -20˚C, and aliquots were thawed after 2 weeks, 2 months, and 6 months at -20˚C. Specimens for β2-microglobulin had the pH adjusted to 6.5-8.0 before freezing. Creatinine, NAG, and ALP levels were determined by a colorimetric assay on a clinical chemistry analyzer and albumin was determined using immunoturbidimetric method on a clinical chemistry analyzer.
Summary of Findings:
ALP levels declined rapidly with frozen storage with 50.5%, 60.4%, and 68.2% declines observed after 2 weeks, 2 months, and 6 months; respectively (P<0.0001, all). NAG levels declined by 13%, 25.6%, and 42.3% after 2 weeks, 2 months or 6 months at -20˚C; respectively (P<0.001, P<0.0001, and P<0.0001, respectively). Albumin levels declined by 14.2% after 2 months of frozen storage (P<0.001) and by 17.1% after 6 months of frozen storage (P<0.0001). Levels of B2M and creatinine were not significantly affected by up to 6 months of frozen storage. Importantly, levels of NAG, ALP and albumin were below the limit of detection in some specimens after frozen storage.
Biospecimens
Preservative Types
- Frozen
Diagnoses:
- Normal
Platform:
Analyte Technology Platform Protein Colorimetric assay Protein Clinical chemistry/auto analyzer Small molecule Colorimetric assay Small molecule Clinical chemistry/auto analyzer Protein Immunoturbidometric assay Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Storage Storage duration 2 weeks
2 months
6 months