Discordant human chorionic gonadotropin results: causes and solutions

Area of Science:

• Clinical Chemistry
• Immunoassay Technology
• Reproductive Endocrinology

Background:

• Variations in laboratory testing can lead to discordant results.
• Accurate human chorionic gonadotropin (hCG) measurement is crucial for diagnosing and monitoring pregnancy and certain neoplasms.
• Different immunoassay methods may exhibit varying performance characteristics.

Purpose of the Study:

• To demonstrate and analyze discordant human chorionic gonadotropin (hCG) results across multiple quantitative assays.
• To identify potential causes and implications of discrepancies in hCG testing.
• To propose guidelines for managing discordant hCG findings.

Main Methods:

• Utilized nine distinct quantitative hCG detection procedures.
• Examined 22 cases exhibiting discordant hCG results.
• Evaluated a two-site monoclonal antibody immunoradiometric assay for its performance characteristics.

Main Results:

• Documented discordant hCG results across the nine tested procedures in 22 cases.
• Observed that a specific two-site monoclonal antibody immunoradiometric assay demonstrated the lowest incidence of aberrant low-positive hCG values in non-pregnant patients without neoplasms.
• Identified variability in assay performance leading to differing results for the same serum specimens.

Conclusions:

• Discordant hCG results are a demonstrable phenomenon influenced by assay methodology.
• The choice of hCG assay can impact diagnostic accuracy, particularly in differentiating true positives from false positives.
• Recommended strategies for managing discordant results include using alternative assay technologies, performing dilution analysis, and sequential hCG testing.