A-350 Myth Debunked: Same UrineAliquot is not Suitable for hCG Test AfterMicroscopic Analysis

Abstract

Abstract Background It has been imparted in the laboratories that the suspending fluid, Lamina, from Iris IQ 200 Analyzer system is prone to interfere with urine human chorionic gonadotropin (hCG) test, especially on a small volume urine specimen. The myth is that the sample is diluted or contaminated by Lamina, which gives falsely negative result for hCG test. An add-on urine pregnancy test was ordered for a specimen, which was completed urinalysis and microscopic analysis. This is the only urine aliquot available, and it is approximately 2mL. This order raised many concerns among laboratory technicians regarding the accuracy of the result. However, no documents or articles were found to support the suspicions. In this study, A serial of experiments was completed to address this concern. Methods Known pregnant patients were confirmed their pregnancies with serum hCG tests prior to collecting the urine specimens. The experiment was conducted with 4 positive patient urines. A series of samples ran on DXI 800 system and the point-of-care (POC) Alere hCG combo cassettes. Then the same specimen performed urinalysis and microscopic analysis on Iris IQ 200 Analyzer. To evaluate the Lamina impact, the sample concentrations were verified with point-of-care (POC) Alere hCG combo cassettes and later DXI 800 system. Meantime, the significance of sample size was also evaluated in the study. Results The final concentrations of the samples were at <5, 5, 10, 15, 20, 25, 30, 40, 50, and 60 mIU/mL. The cutoff for Alere hCG combo cassettes was verified at 20 mIU/mL for urine, the assay gives the accurate result at and above that value. The results are consistent between immunoassay and POCT prior to and after microscopic analysis. Therefore, no significant interferences were identified with the desired sample volume, 3 mL, or short sample volume, 2mL. The volume usage by iQ 200 Analyzer was less than 500 uL. Conclusion In this study, Lamina doesn't cause any interference with hCG values using Alere hCG combo cassettes despite the short sample volume. However, variations between POC urinary hCG devices may contribute to different outcomes. Therefore, a separate validation is highly recommended if a different POC urinary hCG device is involved.