Publications by authors named "G Rynders"
Background: Establishment and improvement of glomerular filtration rate estimating equations requires accurate and precise laboratory measurement procedures (MPs) for filtration markers. The Advanced Research and Diagnostic Laboratory (ARDL) at the University of Minnesota, which has served as the central laboratory for the Chronic Kidney Disease Epidemiology Collaboration since 2009, has implemented several quality assurance measures to monitor the accuracy and stability of filtration marker assays over time.
Methods: To assess longitudinal stability for filtration marker assays, a 40-sample calibration panel was created using pooled serum, divided into multiple frozen aliquots stored at -80 °C.
Context: Cystatin C is becoming an increasingly popular biomarker for estimating glomerular filtration rate, and accurate measurements of cystatin C concentrations are necessary for accurate estimates of glomerular filtration rate.
Objective: To assess the accuracy of cystatin C concentration measurements in laboratories participating in the College of American Pathologists CYS Survey.
Design: Two fresh frozen serum pools, the first from apparently healthy donors and the second from patients with chronic kidney disease, were prepared and distributed to laboratories participating in the CYS Survey along with the 2 usual processed human plasma samples.
Objectives: To evaluate the effect of a freeze-thaw cycle on β-trace protein (βTP) and β2-microglobulin (β2M).
Design And Methods: We compared βTP and β2M concentrations before and after a single freeze-thaw cycle in long-term stored samples from 172 participants of the Third National Health and Nutrition Examination Survey (NHANES III).
Results: Measurements of βTP and β2M before and after freeze-thaw were highly correlated with Spearman's coefficients of 0.