LQCL2501 - CMLE - A Sudden Increase in the Detection of Hepatitis B Antigen-LQCL2501

LQCL2501 - Educational Activity

Pdf Summary

The document is a clinical case study focused on the sudden surge in Hepatitis B surface antigen (HBsAg) detection in a laboratory setting, associated with issues in quality control and potential instrument contamination. The main learning objectives are to understand the testing algorithm for Hepatitis B, analyze the hook effect in screening assays, and develop strategies for managing carryover in immunoassay analyzers.<br /><br />The case begins with a spike in reactive HBsAg specimens, initially detected through a neutralization assay, which led the lab to review quality control (QC) data. Multiple instances of QC failures were observed, and some results were released when negative QC results were outside acceptable limits. A noteworthy trend was the decreasing signal-to-cut-off value in a series of patient results, suggesting a pattern not typical in routine analysis.<br /><br />Hook effect and carryover were significant concerns. Hook effect can result in falsely low patient results if excess antigen suppresses antibody binding, noted by an unexplained decrease in signal in some assays. The case demonstrated a contamination event leading to QC failures and patient result inaccuracies, likely traceable to a malfunctioning sample probe. Dilution studies confirmed the presence of a hook effect in high HBsAg samples, influencing the assessment of carryover and analytical integrity.<br /><br />Resolution involved immediate retesting and notification of stakeholders about potential false positives. The root cause was traced back to an issue with the sample probe, which, when unoptimized, led to contamination isolated to the HBsAg assay. Further testing demonstrated no broader cross-contamination across other assays run on the same platform.<br /><br />The case underscores the need for diligent monitoring of QC data, immediate troubleshooting following QC failures, and consideration of broader contamination issues beyond what current QC measures and manufacturer guidelines assess. This ensures laboratory accuracy and patient safety, even under atypical contamination scenarios.

Keywords

Hepatitis B

HBsAg detection

quality control

instrument contamination

hook effect

immunoassay analyzers

carryover

signal-to-cut-off

sample probe

contamination event