This study was designed to increase the precision and clinical significance of serum creatinine (Cr) measurements by refining the detection methodology through comprehensive laboratory automation and by employing the urea/creatinine ratio(UCR) to detect and mitigate drug interference.We measured the serum Cr concentration via the Siemens sarcosine oxidase enzymatic (SOE) assay. A substantial dataset comprising nearly 2 million records from 98,377 individuals was extracted to form the foundational database for serum UCR analysis. Using the Refine R package, we delineated the reference intervals for UCR. Our laboratory's automated system adeptly identified samples exhibiting aberrant UCR values, prompting a re-evaluation of Cr levels via the Siemens Jaffe (improved alkaline picrate) assay. These Cr measurements were subsequently corroborated against Beckman and Ortho SOE assays and benchmarked against liquid chromatography-isotope dilution tandem mass spectrometry (LC-IDMS/MS), the reference standard.The reference interval for the serum UCR ranged from 0.047 to 0.143(90% CI 0.046-0.048, 0.135-0.148).Among the 58 abnormal samples assessed, the mean deviation in Cr detection for the Siemens, Beckman, and Ortho SOE assays relative to the LC-IDMS/MS results were -61.05%,-53.97%, and -17.18%, respectively. The Siemens Jaffe (improved alkaline picrate) assay revealed a mean deviation of -3.10% compared with that of LC-IDMS/MS. These findings indicate that the improved alkaline picrate assay can accurately reflect the true Cr levels in serum samples affected by calcium dobesilate or etamsylate interference.The implementation of an automated UCR-based screening protocol has been shown to efficiently pinpoint samples with drug-related interference. This strategic approach not only decreases clinical risk but also guarantees the fidelity of serum Cr measurements without undermining the overall productivity of the laboratory's automated workflow.Copyright © 2025 Elsevier B.V. All rights reserved.