Urine stability studies for novel biomarkers of acute kidney injury

Chirag R. Parikh, Isabel Butrymowicz, Angela Yu, Vernon M. Chinchilli, Meyeon Park, Chi Yuan Hsu, W. Brian Reeves, Prasad Devarajan, Paul L. Kimmel, Edward D. Siew, Kathleen D. Liu

Research output: Contribution to journalArticle

37 Citations (Scopus)

Abstract

Background The study of novel urinary biomarkers of acute kidney injury has expanded exponentially. Effective interpretation of data and meaningful comparisons between studies require awareness of factors that can adversely affect measurement. We examined how variations in short-term storage and processing might affect the measurement of urine biomarkers. Study Design Cross-sectional prospective. Setting & Participants Hospitalized patients from 2 sites: Yale New Haven Hospital (n = 50) and University of California, San Francisco Medical Center (n = 36). Predictors We tested the impact of 3 urine processing conditions on these biomarkers: (1) centrifugation and storage at 4°C for 48 hours before freezing at -80°C, (2) centrifugation and storage at 25°C for 48 hours before freezing at -80°C, and (3) uncentrifuged samples immediately frozen at -80°C. Outcomes Urine concentrations of 5 biomarkers: neutrophil gelatinase-associated lipocalin (NGAL), interleukin 18 (IL-18), kidney injury molecule 1 (KIM-1), liver-type fatty acid-binding protein (L-FABP), and cystatin C. Measurements We measured urine biomarkers by established enzyme-linked immunosorbent assay methods. Biomarker values were log-transformed, and agreement with a reference standard of immediate centrifugation and storage at -80°C was compared using concordance correlation coefficients (CCCs). Results Neither storing samples at 4°C for 48 hours nor centrifugation had a significant effect on measured levels, with CCCs higher than 0.9 for all biomarkers tested. For samples stored at 25°C for 48 hours, excellent CCC values (>0.9) also were noted between the test sample and the reference standard for NGAL, cystatin C, L-FABP and KIM-1. However, the CCC for IL-18 between samples stored at 25°C for 48 hours and the reference standard was 0.81 (95% CI, 0.66-0.96). Limitations No comparisons to fresh, unfrozen samples; no evaluation of the effect of protease inhibitors. Conclusions All candidate markers tested using the specified assays showed high stability with both short-term storage at 4°C and without centrifugation prior to freezing. For optimal fidelity, urine for IL-18 measurement should not be stored at 25°C before long-term storage or analysis.

Original languageEnglish (US)
Pages (from-to)567-572
Number of pages6
JournalAmerican Journal of Kidney Diseases
Volume63
Issue number4
DOIs
StatePublished - Apr 2014

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Acute Kidney Injury
Biomarkers
Urine
Centrifugation
Interleukin-18
Freezing
Cystatin C
Fatty Acid-Binding Proteins
Kidney
San Francisco
Wounds and Injuries
Protein C
Protease Inhibitors
Cross-Sectional Studies
Enzyme-Linked Immunosorbent Assay

All Science Journal Classification (ASJC) codes

  • Nephrology

Cite this

Parikh, Chirag R. ; Butrymowicz, Isabel ; Yu, Angela ; Chinchilli, Vernon M. ; Park, Meyeon ; Hsu, Chi Yuan ; Reeves, W. Brian ; Devarajan, Prasad ; Kimmel, Paul L. ; Siew, Edward D. ; Liu, Kathleen D. / Urine stability studies for novel biomarkers of acute kidney injury. In: American Journal of Kidney Diseases. 2014 ; Vol. 63, No. 4. pp. 567-572.
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title = "Urine stability studies for novel biomarkers of acute kidney injury",
abstract = "Background The study of novel urinary biomarkers of acute kidney injury has expanded exponentially. Effective interpretation of data and meaningful comparisons between studies require awareness of factors that can adversely affect measurement. We examined how variations in short-term storage and processing might affect the measurement of urine biomarkers. Study Design Cross-sectional prospective. Setting & Participants Hospitalized patients from 2 sites: Yale New Haven Hospital (n = 50) and University of California, San Francisco Medical Center (n = 36). Predictors We tested the impact of 3 urine processing conditions on these biomarkers: (1) centrifugation and storage at 4°C for 48 hours before freezing at -80°C, (2) centrifugation and storage at 25°C for 48 hours before freezing at -80°C, and (3) uncentrifuged samples immediately frozen at -80°C. Outcomes Urine concentrations of 5 biomarkers: neutrophil gelatinase-associated lipocalin (NGAL), interleukin 18 (IL-18), kidney injury molecule 1 (KIM-1), liver-type fatty acid-binding protein (L-FABP), and cystatin C. Measurements We measured urine biomarkers by established enzyme-linked immunosorbent assay methods. Biomarker values were log-transformed, and agreement with a reference standard of immediate centrifugation and storage at -80°C was compared using concordance correlation coefficients (CCCs). Results Neither storing samples at 4°C for 48 hours nor centrifugation had a significant effect on measured levels, with CCCs higher than 0.9 for all biomarkers tested. For samples stored at 25°C for 48 hours, excellent CCC values (>0.9) also were noted between the test sample and the reference standard for NGAL, cystatin C, L-FABP and KIM-1. However, the CCC for IL-18 between samples stored at 25°C for 48 hours and the reference standard was 0.81 (95{\%} CI, 0.66-0.96). Limitations No comparisons to fresh, unfrozen samples; no evaluation of the effect of protease inhibitors. Conclusions All candidate markers tested using the specified assays showed high stability with both short-term storage at 4°C and without centrifugation prior to freezing. For optimal fidelity, urine for IL-18 measurement should not be stored at 25°C before long-term storage or analysis.",
author = "Parikh, {Chirag R.} and Isabel Butrymowicz and Angela Yu and Chinchilli, {Vernon M.} and Meyeon Park and Hsu, {Chi Yuan} and Reeves, {W. Brian} and Prasad Devarajan and Kimmel, {Paul L.} and Siew, {Edward D.} and Liu, {Kathleen D.}",
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Parikh, CR, Butrymowicz, I, Yu, A, Chinchilli, VM, Park, M, Hsu, CY, Reeves, WB, Devarajan, P, Kimmel, PL, Siew, ED & Liu, KD 2014, 'Urine stability studies for novel biomarkers of acute kidney injury', American Journal of Kidney Diseases, vol. 63, no. 4, pp. 567-572. https://doi.org/10.1053/j.ajkd.2013.09.013

Urine stability studies for novel biomarkers of acute kidney injury. / Parikh, Chirag R.; Butrymowicz, Isabel; Yu, Angela; Chinchilli, Vernon M.; Park, Meyeon; Hsu, Chi Yuan; Reeves, W. Brian; Devarajan, Prasad; Kimmel, Paul L.; Siew, Edward D.; Liu, Kathleen D.

In: American Journal of Kidney Diseases, Vol. 63, No. 4, 04.2014, p. 567-572.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Urine stability studies for novel biomarkers of acute kidney injury

AU - Parikh, Chirag R.

AU - Butrymowicz, Isabel

AU - Yu, Angela

AU - Chinchilli, Vernon M.

AU - Park, Meyeon

AU - Hsu, Chi Yuan

AU - Reeves, W. Brian

AU - Devarajan, Prasad

AU - Kimmel, Paul L.

AU - Siew, Edward D.

AU - Liu, Kathleen D.

PY - 2014/4

Y1 - 2014/4

N2 - Background The study of novel urinary biomarkers of acute kidney injury has expanded exponentially. Effective interpretation of data and meaningful comparisons between studies require awareness of factors that can adversely affect measurement. We examined how variations in short-term storage and processing might affect the measurement of urine biomarkers. Study Design Cross-sectional prospective. Setting & Participants Hospitalized patients from 2 sites: Yale New Haven Hospital (n = 50) and University of California, San Francisco Medical Center (n = 36). Predictors We tested the impact of 3 urine processing conditions on these biomarkers: (1) centrifugation and storage at 4°C for 48 hours before freezing at -80°C, (2) centrifugation and storage at 25°C for 48 hours before freezing at -80°C, and (3) uncentrifuged samples immediately frozen at -80°C. Outcomes Urine concentrations of 5 biomarkers: neutrophil gelatinase-associated lipocalin (NGAL), interleukin 18 (IL-18), kidney injury molecule 1 (KIM-1), liver-type fatty acid-binding protein (L-FABP), and cystatin C. Measurements We measured urine biomarkers by established enzyme-linked immunosorbent assay methods. Biomarker values were log-transformed, and agreement with a reference standard of immediate centrifugation and storage at -80°C was compared using concordance correlation coefficients (CCCs). Results Neither storing samples at 4°C for 48 hours nor centrifugation had a significant effect on measured levels, with CCCs higher than 0.9 for all biomarkers tested. For samples stored at 25°C for 48 hours, excellent CCC values (>0.9) also were noted between the test sample and the reference standard for NGAL, cystatin C, L-FABP and KIM-1. However, the CCC for IL-18 between samples stored at 25°C for 48 hours and the reference standard was 0.81 (95% CI, 0.66-0.96). Limitations No comparisons to fresh, unfrozen samples; no evaluation of the effect of protease inhibitors. Conclusions All candidate markers tested using the specified assays showed high stability with both short-term storage at 4°C and without centrifugation prior to freezing. For optimal fidelity, urine for IL-18 measurement should not be stored at 25°C before long-term storage or analysis.

AB - Background The study of novel urinary biomarkers of acute kidney injury has expanded exponentially. Effective interpretation of data and meaningful comparisons between studies require awareness of factors that can adversely affect measurement. We examined how variations in short-term storage and processing might affect the measurement of urine biomarkers. Study Design Cross-sectional prospective. Setting & Participants Hospitalized patients from 2 sites: Yale New Haven Hospital (n = 50) and University of California, San Francisco Medical Center (n = 36). Predictors We tested the impact of 3 urine processing conditions on these biomarkers: (1) centrifugation and storage at 4°C for 48 hours before freezing at -80°C, (2) centrifugation and storage at 25°C for 48 hours before freezing at -80°C, and (3) uncentrifuged samples immediately frozen at -80°C. Outcomes Urine concentrations of 5 biomarkers: neutrophil gelatinase-associated lipocalin (NGAL), interleukin 18 (IL-18), kidney injury molecule 1 (KIM-1), liver-type fatty acid-binding protein (L-FABP), and cystatin C. Measurements We measured urine biomarkers by established enzyme-linked immunosorbent assay methods. Biomarker values were log-transformed, and agreement with a reference standard of immediate centrifugation and storage at -80°C was compared using concordance correlation coefficients (CCCs). Results Neither storing samples at 4°C for 48 hours nor centrifugation had a significant effect on measured levels, with CCCs higher than 0.9 for all biomarkers tested. For samples stored at 25°C for 48 hours, excellent CCC values (>0.9) also were noted between the test sample and the reference standard for NGAL, cystatin C, L-FABP and KIM-1. However, the CCC for IL-18 between samples stored at 25°C for 48 hours and the reference standard was 0.81 (95% CI, 0.66-0.96). Limitations No comparisons to fresh, unfrozen samples; no evaluation of the effect of protease inhibitors. Conclusions All candidate markers tested using the specified assays showed high stability with both short-term storage at 4°C and without centrifugation prior to freezing. For optimal fidelity, urine for IL-18 measurement should not be stored at 25°C before long-term storage or analysis.

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