TY - JOUR
T1 - Storage time and urine biomarker levels in the ASSESS-AKI study
AU - ASSESS-AKI Study Investigators
AU - Liu, Kathleen D.
AU - Siew, Edward D.
AU - Reeves, W. Brian
AU - Himmelfarb, Jonathan
AU - Go, Alan S.
AU - Hsu, Chi Yuan
AU - Bennett, Michael R.
AU - Devarajan, Prasad
AU - Ikizler, T. Alp
AU - Kaufman, James S.
AU - Kimmel, Paul L.
AU - Chinchilli, Vernon M.
AU - Parikh, Chirag R.
AU - Ghahramani, Nasrollah
AU - Kong, Lan
AU - Wang, Ming
AU - Farace, Elana
AU - Hsu, Raymond
AU - Tan, Thida
AU - Ordonez, Juan D.
AU - Zheng, Sijie
AU - Lewis, Julia B.
AU - Ware, Lorraine
AU - Coca, Steven
AU - Moledina, Dennis G.
AU - Garg, Amit
AU - Zappitelli, Michael
AU - Wurfel, Mark
PY - 2016/10
Y1 - 2016/10
N2 - Background: Although stored urine samples are often used in biomarker studies focused on acute and chronic kidney disease, how storage time impacts biomarker levels is not well understood. Methods: 866 subjects enrolled in the NIDDK-sponsored ASsessment, Serial Evaluation, and Subsequent Sequelae in Acute Kidney Injury (ASSESS-AKI) Study were included. Samples were processed under standard conditions and stored at -70°C until analyzed. Kidney injury molecule- 1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), interleukin-18 (IL-18), and liver fatty acid binding protein (L-FABP) were measured in urine samples collected during the index hospitalization or an outpatient visit 3 months later. Mixed effects models were used to determine the effect of storage time on biomarker levels and stratified by visit. Results: Median storage was 17.8 months (25±75% IQR 10.6±23.7) for samples from the index hospitalization and 14.6 months (IQR 7.3±20.4) for outpatient samples. In the mixed effects models, the only significant association between storage time and biomarker concentration was for KIM-1 in outpatient samples, where each month of storage was associated with a 1.7% decrease (95% CI -3% to -0.3%). There was no relationship between storage time and KIM-1 levels in samples from the index hospitalization. Conclusion: There was no significant impact of storage time over a median of 18 months on urine KIM- 1, NGAL, IL-18 or L-FABP in hospitalized samples; a statistically significant effect towards a decrease over time was noted for KIM-1 in outpatient samples. Additional studies are needed to determine whether longer periods of storage at -70°C systematically impact levels of these analytes.
AB - Background: Although stored urine samples are often used in biomarker studies focused on acute and chronic kidney disease, how storage time impacts biomarker levels is not well understood. Methods: 866 subjects enrolled in the NIDDK-sponsored ASsessment, Serial Evaluation, and Subsequent Sequelae in Acute Kidney Injury (ASSESS-AKI) Study were included. Samples were processed under standard conditions and stored at -70°C until analyzed. Kidney injury molecule- 1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), interleukin-18 (IL-18), and liver fatty acid binding protein (L-FABP) were measured in urine samples collected during the index hospitalization or an outpatient visit 3 months later. Mixed effects models were used to determine the effect of storage time on biomarker levels and stratified by visit. Results: Median storage was 17.8 months (25±75% IQR 10.6±23.7) for samples from the index hospitalization and 14.6 months (IQR 7.3±20.4) for outpatient samples. In the mixed effects models, the only significant association between storage time and biomarker concentration was for KIM-1 in outpatient samples, where each month of storage was associated with a 1.7% decrease (95% CI -3% to -0.3%). There was no relationship between storage time and KIM-1 levels in samples from the index hospitalization. Conclusion: There was no significant impact of storage time over a median of 18 months on urine KIM- 1, NGAL, IL-18 or L-FABP in hospitalized samples; a statistically significant effect towards a decrease over time was noted for KIM-1 in outpatient samples. Additional studies are needed to determine whether longer periods of storage at -70°C systematically impact levels of these analytes.
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U2 - 10.1371/journal.pone.0164832
DO - 10.1371/journal.pone.0164832
M3 - Article
C2 - 27788160
AN - SCOPUS:84992694879
SN - 1932-6203
VL - 11
JO - PloS one
JF - PloS one
IS - 10
M1 - e0164832
ER -