Utility of the I-index as a pre-screening tool for total bilirubin testing: a retrospective study in a regional hospital

Adv Lab Med. 2026 Jan 22;7(2):153-155. doi: 10.1515/almed-2025-0161. eCollection 2026 Jun.

Abstract

Objectives: This study evaluates the efficacy of the icteric index as a pre-screening tool for hyperbilirubinemia in adult patients.

Methods: The use of this index would help optimize the use of clinical laboratory resources.

Results: A retrospective analysis of 3,194 serum samples revealed a strong correlation between icteric index and total bilirubin levels (r=0.972), with an area under the ROC curve of 0.90. An index cut-off value of 1.2 yielded a sensitivity of 100 % and a specificity of 87 %. This performance guarantees the detection of the totality of hyperbilirubinemia cases and the absence of false negatives, albeit with some false positives. This method would avoid around 79 % of unnecessary total bilirubin tests, resulting in estimated annual cost savings of over 1,500 Euros.

Conclusions: In conclusion, the icteric index is an effective, inexpensive, and safe tool for improving the diagnostic performance of laboratory tests without compromising the quality of care.

Keywords: diagnostic performance; hyperbilirubinemia; icteric index; total bilirubin.