Establishment of CA19-9 reference intervals in an apparently healthy adult population in Singapore.

BACKGROUND: CA19-9 is elevated in pancreatic cancer and other malignancies, and commonly used in clinical practice. Unfortunately, CA19-9 immunoassays are not harmonized, and reference intervals may differ between assays. The aim of this study was to establish the reference interval of the ADVIA Centaur/Atellica IM CA19-9 assay in an apparently healthy Singapore adult population. METHODS: This is a retrospective cross-sectional study. De-identified data from Health Screening participants were extracted from our database. Subjects with biochemical results suggesting anaemia, diabetes mellitus, viral hepatitis or abnormal liver, and renal and tumour markers were excluded. Outlier and subclass analyses by age and sex were performed. CA19-9 reference limits and 90% confidence intervals were then determined for candidate subclasses. RESULTS: Data from 12,174 subjects (5846 males and 6328 females) were available after exclusion criteria were applied. CA19-9 results did not follow a normal distribution and were higher in females compared to males (P < .001). Although CA19-9 means were statistically different between certain age groups, the evaluable 99th percentile reference limits were not statistically different. The overall 99th percentile reference limits for the Centaur/Atellica CA19-9 assay was 37 U/mL for males 21-80 years, and 60 U/mL for females 21-80 years. CONCLUSIONS: Our results suggest that separate CA19-9 reference intervals should be applied for males and females.

Commutability assessment of human urine certified reference materials for albumin and creatinine on multiple clinical analyzers using different statistical models.

Urine albumin concentration and albumin-creatinine ratio are important for the screening of early-stage kidney damage. Commutable urine certified reference materials (CRMs) for albumin and creatinine are necessary for standardization of urine albumin and accurate measurement of albumin-urine ratio. Two urine CRMs for albumin and creatinine with certified values determined using higher-order reference measurement procedures were evaluated for their commutability on five brands/models of clinical analyzers where different reagent kits were used, including Roche Cobas c702, Roche Cobas c311, Siemens Atellica CH, Beckman Coulter AU5800, and Abbott Architect c16000. The commutability study was conducted by measuring at least 26 authentic patient urine samples and the human urine CRMs using both reference measurement procedures and the routine methods. Both the linear regression model suggested by the Clinical and Laboratory Standard Institute (CLSI) guidelines and log-transformed model recommended by the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) Commutability Working Group were used to evaluate the commutability of the human urine CRMs. The commutability of the human urine CRMs was found to be generally satisfactory on all five clinical analyzers for both albumin and creatinine, suggesting that they are suitable to be used routinely by clinical laboratories as quality control or for method validation of urine albumin and creatinine measurements.