Comparison of eight routine unpublished LC–MS/MS methods for the simultaneous measurement of testosterone and androstenedione in serum.

Background Liquid-chromatography tandem mass spectrometry (LC–MS/MS) has become the method of choice in steroid hormone measurement. However, little information on the mutual agreement of LC–MS/MS methods is available. We compared eight routine unpublished LC–MS/MS methods for the simultaneous measurement of testosterone and androstenedione. Methods Sixty random serum samples from male and female volunteers were analysed in duplicate by eight routine LC–MS/MS methods. We performed Passing–Bablok regression analyses and calculated Pearson's correlation coefficients to assess the agreement of the methods investigated with one published method known to be accurate. Intra-assay CV of each method was calculated from duplicate results, recoveries for each method were calculated from six spiked samples. Furthermore, a CV between the investigated methods was calculated. Results The concentrations ranged from 0.05–1.26 nmol/L, 6.15–24.44 nmol/L and 0.15–4.78 nmol/L for testosterone in females, testosterone in males and androstenedione, respectively. The intra-assay CVs were between 3.7–16.0%, 0.9–5.2% and 1.2–9.5% for testosterone in females, testosterone in males and androstenedione, respectively. The slopes of the regression lines ranged between 0.90–1.25, 0.87–1.24 and 0.94–1.31 for testosterone concentrations in females, all testosterone values and androstenedione, respectively. Inter-method CVs were 24%, 14% and 29% for testosterone for concentrations in females and males and androstenedione, respectively. These compare unfavourably to the variation found earlier in published methods. Conclusion Although most routine LC–MS/MS methods investigated here showed a reasonable agreement, some of the assays showed a high variation. The observed differences in standardization should be taken into account when applying reference values, or should, preferably, be solved. [ABSTRACT FROM AUTHOR]