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Abstract: PO2252

Examining Accuracy and Reproducibility of Novel Creatinine and Urea Rapid Measurements in Human Saliva

Session Information

Category: Pathology and Lab Medicine

  • 1602 Pathology and Lab Medicine: Clinical

Authors

  • Beshay, Manal, Intelligent Optical Systems, Inc., Torrance, California, United States
  • Kalantar-Zadeh, Kamyar, University of California Irvine, Irvine, California, United States
  • Nguyen, Trong Duc, Intelligent Optical Systems, Inc., Torrance, California, United States
  • Ortega, Maria, Intelligent Optical Systems, Inc., Torrance, California, United States
  • Nguyen, Danh V., University of California Irvine, Irvine, California, United States
  • Rhee, Connie, University of California Irvine, Irvine, California, United States
Background

Rapid and frequent point-of-care kidney filtration markers that do not require laborious blood specimen draws/processing can improve CKD patient care. The use of saliva as a non-invasive biofluid for monitoring kidney function biomarkers such as Creatinine (Cr) and Urea, addresses a clinical need in support of telemedicine.

Methods

We developed novel Enhanced Enzyme and Immunoassay-based Lateral Flow (ELF) for quantitative measurement of 2 kidney filtration markers in human saliva using highly selective reagents for optimum specificity. We used healthy donor saliva samples spiked with known levels of Cr and Urea. Standard calibration curves (SCCs) for each marker were established with nonlinear 4-parameter logistic curve fitting in triplicate at each spiked level. Accuracy/fit of the SCC was assessed using the coefficient of determination (R2).

Results

SCC fitted to relative optical intensities (ratio of test to control lines vs spiked Urea (0-180 mg/dL) and Cr (0- 6 mg/dL) showed excellent correlation (R2=0.992 and 0.999 respectively). Intra-assay variation showed that repeatability is very good with CV <15%, and CV <10% for Cr and Urea, respectively, throughout the dynamic range of measurements. Assessment of inter-assay variation (measurements over 8 days) showed that reproducibility is acceptable with CV <10% and <13% for Cr and Urea, respectively, throughout most of the dynamic range. Preliminary assessment of long-term reproducibility (stability) up to 91 and 216 days for Urea and Cr assays, respectively indicated similar performance.[figure]

Conclusion

Cr and Urea can be measured in human saliva with acceptable ELF assay characteristics including accuracy, repeatability, reproducibility, and long-term stability. Future validation studies may lead to a saliva testing framework for kidney function markers and a potential paradigm-shift in CKD monitoring.

Funding

  • NIDDK Support