Context: Measurement of anti-Müllerian hormone (AMH) is perceived as reliable, but the literature reveals discrepancies in reported within-subject variability and between-method conversion factors. Recent studies suggest that AMH may be prone to preanalytical instability. We therefore examined the published evidence on the performance of current and historic AMH assays in terms of the assessment of sample stability, within-patient variability, and comparability of the assay methods.
Evidence acquisition: We reviewed studies (manuscripts or abstracts) measuring AMH, published in peer-reviewed journals between January 1, 1990, and August 1, 2013, using appropriate PubMed/Medline searches.
Evidence synthesis: AMH levels in specimens left at room temperature for varying periods increased by 20% in one study and by almost 60% in another, depending on duration and the AMH assay used. Even at -20°C, increased AMH concentrations were observed. An increase over expected values of 20-30% or 57%, respectively, was observed after 2-fold dilution in two linearity-of-dilution studies, but not in others. Several studies investigating within-cycle variability of AMH reported conflicting results, although most studies suggest that variability of AMH within the menstrual cycle appears to be small. However, between-sample variability without regard to menstrual cycle as well as within-sample variation appears to be higher using the GenII AMH assay than with previous assays, a fact now conceded by the kit manufacturer. Studies comparing first-generation AMH assays with each other and with the GenII assay reported widely varying differences.
Conclusions: AMH may exhibit assay-specific preanalytical instability. Robust protocols for the development and validation of commercial AMH assays are required.