[False positives in female testosterone testing and the diagnostic value of mass spectrometry]

To investigate the proportion of pseudo-elevated testosterone levels detected by chemiluminescent immunoassay (CLIA) in female patients and to evaluate the application value of liquid chromatography-tandem mass spectrometry (LC-MS/MS) in improving the accuracy of testosterone detection in this population.

A retrospective analysis was conducted on data collected from female patients who presented at Peking University People' s Hospital from January 1, 2020 to May 1, 2024. These patients were initially identified with elevated testosterone levels through CLIA and subsequently underwent additional blood sampling for confirmatory testing using LC-MS/MS. Based on LC-MS/MS results, the patients were categorized into the pseudo-elevated group and the true-elevated group. Dif-ferences in the testosterone levels between the two groups were compared, the false-positive rate of CLIA was calcula-ted, and further evaluations conducted in the pseudo-elevated group were analyzed.

A total of 287 female patients with elevated testosterone levels detected by CLIA were included in the study. According to the LC-MS/MS results, 178 cases (62.0%) were classified into the pseudo-elevated group, while 109 cases (38.0%) were classified into the true-elevated group. The mean testosterone levels measured by CLIA were (3.63±1.60) nmol/L in the pseudo-elevated group and (4.13±2.20) nmol/L in the true-elevated group, showing a statistically significant difference (P < 0.05). The false-positive rate of CLIA in detecting testosterone levels in women was 62.0%, and the area under the receiver operating characteristic (ROC) curve (AUC) for CLIA was 0.601 (95%CI: 0.534-0.668) indicating low diagnostic accuracy. Among the pseudo-elevated group, 40.45% of patients underwent multiple CLIA retests, and some patients were subjected to unnecessary clinical evaluations, including imaging and hormonal testing, which significantly increased patient burden.

This study highlights the high false-positive rate of CLIA in detecting testosterone levels in female patients, which can result in misdiagnosis, repeated testing, and unnecessary clinical evaluations, thereby increasing patient burden and resulting in inefficient use of medical resources.LC-MS/MS significantly enhances the accuracy of testosterone detection in women and is strongly recommended as the confirmatory test for female patients with elevated testosterone levels initially detected by CLIA.