BUN Delta Checks and Their Utility in the Modern Clinical Laboratory

• Published in: American journal of clinical pathology 2018-09, Vol.150 (suppl_1), p.S153-S153
• Main Authors: Toyama, Aimi, Yousaf, Hira, Karger, Amy B
• Format: Article
• Language: English
• Subjects: End-stage renal disease; Hemodialysis; Kidney diseases; Kidneys; Laboratories; Patients; Quality assurance; Quality control; Urea
• ISSN: 0002-9173; 1943-7722
• DOI: 10.1093/ajcp/aqy112.359

Abstract Delta checks are flagged in the laboratory when an analyte in question is significantly different from the most recent previous value. The new value is then held up in the system to be reviewed by a medical technologist, who must determine if this change was due to a laboratory error. Historically, this was beneficial for identifying errors when automated laboratory methods were not in place, but today there are far more advanced quality control and quality assurance measures available, making the utility of delta checks increasingly questionable. Within the University of Minnesota/Fairview Health system, the blood urea nitrogen (BUN) value is one of the analytes that generates a high number of delta checks. We thus performed an internal study to determine if BUN delta checks had utility in identifying erroneous laboratory results or if the values could be explained by true pathophysiological changes. All BUN results that flagged delta checks during the month of November 2017 were included in this study for chart review (n = 59). Patients’ laboratory values, physician notes, and ancillary studies were reviewed to determine if there was a pathophysiological explanation for the significant increase or decrease in BUN value. Among the 59 BUN results analyzed, 34 (57.6%) results had delta checks due to a negative change in values, while 25 (42.4%) were due to a positive change. Out of those with a negative change in BUN, 28 (82.4%) were due to the patient having undergone hemodialysis since the last BUN result, 6 (17.6%) were due to improvement from a recent pathophysiological condition (ie, acute kidney injury), and 0 (0%) were due to laboratory error. Out of those with a positive change in BUN, 13 (37.1%) were due to acute kidney injury, 12 (48.0%) had acute worsening of known chronic or end-stage renal disease, and 0 (0%) were due to laboratory error. In short, this retrospective analysis identified that none of the BUN delta checks were a result of laboratory error, and all were explained by a true pathophysiological change occurring in the patient. If the purpose of the delta check is to identify laboratory errors, the BUN delta check is nonessential, and furthermore it delays results that would otherwise be auto-verified and creates unnecessary workload for the medical technologists who have to manually review these results. To increase efficiency and laboratory workflow, an analysis such as this is beneficial to determine if delta checks for ce