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Reevaluating the Icterus Index Cutoff of a Jaffé Creatinine Method. J Appl Lab Med 2022 Sep 01;7(5):1151-1157

Date

07/29/2022

Pubmed ID

35899580

DOI

10.1093/jalm/jfac045

Scopus ID

2-s2.0-85137136078 (requires institutional sign-in at Scopus site)   1 Citation

Abstract

BACKGROUND: The aim of this study was to redefine the icterus index cutoff for the Roche Jaffé creatinine method using both conjugated and unconjugated bilirubin on 3 Roche cobas modules (c311, c501, and c701/c702) at laboratories across our hospital network.

METHODS: Interference was evaluated by adding conjugated bilirubin (as bilirubin conjugate, ditaurate) and unconjugated bilirubin to pooled remnant plasma. The effects of conjugated and unconjugated bilirubin were tested separately to assess the contribution of each species. The magnitude of interference was calculated as both absolute and percentage error with total allowable error limits set at 0.1 mg/dL (8 µmol/L or 8%).

RESULTS: Analysis of interference data across the 3 Roche modules did not show bias exceeding our total allowable error limits for plasma creatinine up to a conjugated bilirubin icterus index of 16.2 (approximately 16.2 mg/dL or 277 μmol/L) or an unconjugated bilirubin icterus index of 18.5 (approximately 18.5 mg/dL or 316 μmol/L), the highest concentrations tested.

CONCLUSIONS: Our results demonstrate that the Roche Jaffé method exhibits acceptable performance in the presence of icterus at icterus indexes above the manufacturer's current recommendations of 5 (approximately 5 mg/dL or 86 μmol/L) and 10 (approximately 10 mg/dL or 171 μmol/L) for conjugated and unconjugated bilirubin, respectively. We have updated the icterus index in our hospital system to 16 for conjugated bilirubin and 18 for unconjugated bilirubin.

Author List

Alvarez YF, Kelliher MT, Hubbard JA, Nerenz RD, Cervinski MA

Author

Robert D. Nerenz PhD Associate Professor in the Pathology department at Medical College of Wisconsin




MESH terms used to index this publication - Major topics in bold

Bilirubin
Creatinine
Humans
Jaundice