Open AccessConjugated bilirubin as a reflex test for increased total bilirubin in apparently healthy population
Author(s) -
Zhang GuoMing,
Hu ZhiDe
Publication year - 2018
Publication title -
journal of clinical laboratory analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.536
H-Index - 50
eISSN - 1098-2825
pISSN - 0887-8013
DOI - 10.1002/jcla.22233
Subject(s) - bilirubin , medicine , direct bilirubin , gastroenterology , population , receiver operating characteristic , chemistry , biochemistry , alkaline phosphatase , environmental health , enzyme
Background Total, unconjugated and conjugated bilirubin levels are usually ordered together in health check‐up populations. The aim of this study was to investigate whether using increased total bilirubin ( TBIL ) as a reflex test can reduce conjugated bilirubin ( CBIL ) test. Methods Medical records of 8433 males and 4496 females who visited Shuyang People's Hospital for health check‐ups were retrospectively reviewed and the fasting serum TBIL , unconjugated bilirubin ( UBIL ) and CBIL of patients were extracted. Reference intervals for TBIL , UBIL , CBIL and C/ TBIL were established using Q 2.5 to Q 97.5 . The relationship between TBIL and CBIL was analyzed by Spearman's approach. Receiver operating characteristics ( ROC ) curve analysis was used to evaluate the predictive accuracy of TBIL for abnormal CBIL and UBIL . Results The reference intervals for TBIL in males and females were 6.9‐29.3 μmol/L and 6.1‐23.8 μmol/L, respectively. For CBIL , the reference intervals were 1.9‐10.4 μmol/L and 1.6‐8.8 μmol/L for males and females, respectively. CBIL was significantly positively correlated with TBIL , either in males ( r =.75) or females ( r =.73). Area under curve ( AUC ) of TBIL for predicting abnormal CBIL was 0.99 in both male and females. The optimal threshold of TBIL for predicting abnormal CBIL and UBIL were 21.0 μmol/L in males and 17.0 μmol/L in females. At these thresholds, <2% of subjects with abnormal CBIL or CBIL might be missed, but approximately 87% of the CBIL test could be eliminated. Conclusion Conjugated bilirubin measurement is not needed for the apparently healthy males with TBIL <21.0 μmol/L or females with TBIL <17.0 μmol/L.