Determination of serum anti‐Müllerian hormone concentrations for the diagnosis of granulosa‐cell tumours in mares

Reasons for performing study: Endocrinological assays are important for evaluation of mares with granulosa‐cell tumours (GCTs), and our research in mares indicates that anti‐Müllerian hormone (AMH) may be a good biomarker for this type of ovarian tumour. Objectives: To evaluate the use of serum AMH concentrations for endocrine diagnosis of GCTs in mares. Methods: Archived serum samples (n = 403) previously assayed for determination of serum inhibin, testosterone and progesterone concentrations (GCT panel) were assayed for serum AMH concentrations using a heterologous enzyme‐linked immunosorbent assay previously validated by our laboratory. For a subset (n = 44) of these samples, a clinical diagnosis of GCT was confirmed by histopathology. Results: Overall, the sensitivity of AMH (98%) for detection of histologically confirmed GCTs was significantly (P<0.05) greater than that of either inhibin (80%) or testosterone (48%) or the combination of inhibin and testosterone (84%). Conclusions: Determination of serum AMH concentrations is a useful biomarker for detection of GCTs in the mare. Potential relevance: Measurement of serum AMH concentrations can be used for diagnosis of GCTs in the mare. As serum AMH concentrations do not vary significantly during the oestrous cycle or pregnancy, interpretation of these results is not confounded by these physiological states.