SAT-043 Utility of Ultrasensitive Inhibin B Measurement for the Management of Men with Non-Obstructive Azoospermia

Inhibin B measurement by conventional assay(s) may be useful in the assessment of spermatogenesis in infertile male patients, especially in cases of azoospermia. Indeed, numerous previous studies have shown that Inhibin B could be helpful to predict a positive testicular sperm extraction (TESE). However, an undetectable Inhibin B concentration (<10pg/mL) does not predict a TESE failure in all cases. These findings explained that most medical centers have precluded the use of Inhibin B assay in the pre-operative hormonal assessment of azoospermic men. Recently, an ultrasensitive Inhibin B assay has been developed allowing the measurement of concentrations below 10pg/mL. The current study aims to assess the clinical relevance of this new assay in men with azoospermia with undetectable Inhibin B levels by conventional assay(s). Methods: This retrospective study included 71 non-obstructive azoospermic men who had undetectable Inhibin B levels (i.e. <10pg/mL by Gen II ELISA from Beckman Coulter, USA) and who underwent a TESE procedure between 2013 and 2019 in the Lille University Hospital. Serum LH, FSH and testosterone levels were systematically measured by routine immunoassays. Cryopreserved serum samples were used to perform ultrasensitive Inhibin B assay (Ultrasensitive Inhibin B, AL-195, Ansh Labs, USA). Additional hormonal assays including Inhibin A, Activin B and Activin A were performed on available subset of samples. Results: The TESE was successful, allowing sperm cryopreservation in 32.5 % (25/71) of the cases. No significant statistical difference was found in FSH, LH, or testosterone levels between patients with positive or negative TESE. By contrast, men with positive TESE had more than twice higher serum ultrasensitive Inhibin B levels (median 5.03pg/mL [1.93-8.5] vs. 2.19pg/mL [0.2-4.72], p=0.006). An ultrasensitive Inhibin B serum level >3.67 pg/mL (determined by ROC analysis) was associated with increased odds ratio (OR= 4.82; 95% CI: 1.647-12.93) for positive TESE. Inhibin A, Activin B and Activin A serum concentrations did not differ significantly between the two groups. Conclusion: FSH measurement which is routinely performed in men with azoospermia was not predictive of successful TESE whereas, Inhibin B was found to be a valuable marker in predicting TESE success in this population using ultrasensitive Inhibin B assay.