Extent-of-Equivalence Assessment of Certified Reference Materials for Albumin and Creatinine in Human Urine

Published

November 19, 2025

Author(s)

Ashley Green, Johanna Camara, Elena Wood, Nathanael Heckert

Abstract

Accurate urine albumin test results are crucial for diagnosing and managing kidney disease. To ensure accuracy and consistency, clinical lab results need to be standardized. This can be achieved by establishing a calibration hierarchy that links clinical results to the foundational unit of measure, the International System of Units (SI). The National Institute of Standards and Technology (NIST) and the Health Sciences Authority (HSA), Singapore, have developed two certified reference materials (CRMs) for albumin and creatinine in human urine. An extent-of-equivalence assessment was performed to compare the certified values of urine albumin and creatinine in the two human urine CRMs (NIST SRM 3666 and HRM-3004A). The overlap observed in the equivalence assessment between the measured [X_i ± U_95 (X_i )] and certified [C_i ± U_95 (C_i )] intervals indicate that the intervals agree within their assigned uncertainties with about a 95 % level of confidence. Therefore, the CRMs were deemed equivalent at the 95 % level of confidence for measuring urine albumin and creatinine. The equivalence of these CRMs ensures that the interchangeable use in a calibration hierarchy does not introduce additional bias, thereby maintaining the integrity of the calibration hierarchy and ensuring that measurement results remain reliable and without significant impacts on uncertainty or quality. By establishing a robust calibration hierarchy for urine albumin and creatinine measurements, we can enhance the reliability and accuracy of clinical laboratory measurements for kidney disease diagnosis and monitoring, ultimately leading to better patient outcomes and more effective healthcare management.

Citation

Special Publication (NIST SP) - 260-262

Report Number

260-262

NIST Pub Series

Special Publication (NIST SP)

Pub Type

NIST Pubs

Download Paper

https://doi.org/10.6028/NIST.SP.260-262

Local Download

Keywords

Albumin, Calibration Hierarchy, Certified Reference Material (CRM), Creatinine, Extent-of-equivalence, Metrological Traceability, Standard Reference Material (SRM)

Citation

Green, A. , Camara, J. , Wood, E. and Heckert, N. (2025), Extent-of-Equivalence Assessment of Certified Reference Materials for Albumin and Creatinine in Human Urine, Special Publication (NIST SP), National Institute of Standards and Technology, Gaithersburg, MD, [online], https://doi.org/10.6028/NIST.SP.260-262, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=960896 (Accessed November 20, 2025)