Current Practices When Reporting Quantitative Human Chorionic Gonadotropin Test Results

Abstract

Abstract Background Quantitative human chorionic gonadotropin (hCG) tests are commonly used to determine a woman’s pregnancy status. Discrete results are evaluated and/or interpreted against a reference interval or cutoff. Reporting practices across laboratories have not been investigated. Methods A voluntary questionnaire was distributed to 6433 laboratories participating in a general chemistry proficiency testing survey. Results Responses were received from 3568 (55%) laboratories. Overall, 31% used a single reference cutoff, with 42% and 14% using values of 5.0 and 25.0 IU/L, respectively. In total, 68% of laboratories provided result interpretations, most frequently “negative” and “positive.” Reference intervals based on chronological age were offered by 9% of laboratories; 60% reported gestational age-based intervals. In addition, 25% provided male-specific reference intervals, with 2.0 IU/L being the most commonly used single-point cutoff. Only 12% of laboratories offered a separate, orderable test for hCG as a tumor marker, with 5.0 IU/L as the most frequently used reference threshold. Nearly half of laboratories used assay product insert data as the reference interval source. Conclusions There is wide variation when reporting quantitative hCG results. Despite a well-established reference limit of <5.0 IU/L for nonpregnant women, fewer than half of laboratories used this cutoff. The reporting of gestational age-based reference intervals is more common than those based on chronological age despite greater clinical utility for the latter. Data-driven guidelines for reporting quantitative hCG test results could deliver more consistent result interpretation.