BACKGROUND: Urinary kidney injury molecule-1 (KIM-1) is a recently discovered biomarker for early renal damage. However, little is known about the collection and storage requirements prior to its measurement in human urine. METHODS: Samples of healthy volunteers were collected and aliquoted. The effect of pre-freezing time, thawing, addition of protease inhibitors, centrifugation, storage time (up to 1.5 years) and temperature (4°C, -20°C and -80°C) was tested. RESULTS: Addition of protease inhibitors and centrifugation prior to freezing did not affect the KIM-1 measurements. When samples were kept at room temperature for longer than 3 h before freezing or defrosted more than 1 h before measurement, mean KIM-1 values differed significantly compared to aliquots with minimal pre-freezing and thawing time. Samples frozen at -80°C were stable for up to 1.5 years; however an increasing number of freeze-thaw cycles adversely affected KIM-1 measurements. When stored at 4°C and -20°C, samples were less stable compared to those stored at -80°C. CONCLUSIONS: This study recommends that urine samples collected for KIM-1 measurements are frozen within 3 h after voiding and only be defrosted immediately prior to measurement. Addition of protease inhibitor and centrifugation prior to measurement is not necessary. Samples are preferably stored at -80°C and freeze-thaw cycles should be avoided.
BACKGROUND: Urinary kidney injury molecule-1 (KIM-1) is a recently discovered biomarker for early renal damage. However, little is known about the collection and storage requirements prior to its measurement in human urine. METHODS: Samples of healthy volunteers were collected and aliquoted. The effect of pre-freezing time, thawing, addition of protease inhibitors, centrifugation, storage time (up to 1.5 years) and temperature (4°C, -20°C and -80°C) was tested. RESULTS: Addition of protease inhibitors and centrifugation prior to freezing did not affect the KIM-1 measurements. When samples were kept at room temperature for longer than 3 h before freezing or defrosted more than 1 h before measurement, mean KIM-1 values differed significantly compared to aliquots with minimal pre-freezing and thawing time. Samples frozen at -80°C were stable for up to 1.5 years; however an increasing number of freeze-thaw cycles adversely affected KIM-1 measurements. When stored at 4°C and -20°C, samples were less stable compared to those stored at -80°C. CONCLUSIONS: This study recommends that urine samples collected for KIM-1 measurements are frozen within 3 h after voiding and only be defrosted immediately prior to measurement. Addition of protease inhibitor and centrifugation prior to measurement is not necessary. Samples are preferably stored at -80°C and freeze-thaw cycles should be avoided.
Authors: Meredith P Schuh; Edward Nehus; Qing Ma; Christopher Haffner; Michael Bennett; Catherine D Krawczeski; Prasad Devarajan Journal: Am J Kidney Dis Date: 2015-05-29 Impact factor: 8.860
Authors: Chi-Yuan Hsu; Dawei Xie; Sushrut S Waikar; Joseph V Bonventre; Xiaoming Zhang; Venkata Sabbisetti; Theodore E Mifflin; Josef Coresh; Clarissa J Diamantidis; Jiang He; Claudia M Lora; Edgar R Miller; Robert G Nelson; Akinlolu O Ojo; Mahboob Rahman; Jeffrey R Schelling; Francis P Wilson; Paul L Kimmel; Harold I Feldman; Ramachandran S Vasan; Kathleen D Liu Journal: Kidney Int Date: 2016-10-28 Impact factor: 10.612
Authors: Kathleen D Liu; Edward D Siew; W Brian Reeves; Jonathan Himmelfarb; Alan S Go; Chi-Yuan Hsu; Michael R Bennett; Prasad Devarajan; T Alp Ikizler; James S Kaufman; Paul L Kimmel; Vernon M Chinchilli; Chirag R Parikh Journal: PLoS One Date: 2016-10-27 Impact factor: 3.240
Authors: Ellen M Cody; James E Rose; Bin Huang; Tingting Qiu; Hermine I Brunner; Prasad Devarajan Journal: Front Pediatr Date: 2022-07-29 Impact factor: 3.569