ESPE Abstracts (2019) 92 P3-238

Bilateral Testicular Atrophy and Normal Inhibin B level: A Paradoxal Clinical Finding For A Rare Biochemical Cause !

Leïla ESSADDAM1,2, Marie PIKETTY3, Wafa KALLALI1,2, Rahma GUEDRI1,2, Laura GONZALEZ3, Nadia MATTOUSSI1,2, Michel POLAK3, Saayda BEN BECHER1,2

1Children Hospital Bechir Hamza of Tunis, Tunis, Tunisia. 2Université de Tunis El Manar, Tunis, Tunisia. 3Hôpital Necker, Paris, France

Background: Testicular atrophy is a rare complication following inguinal hernia repair particularly in children<2 years and those with an undescended testis at highest risk> with an undescended testis. Inhibin B is secreted from the testis as a product of Sertoli cells, and has been suggested as a good marker for spermatogenesis. Its value is expected to be very low in children with bilateral testicular atrophy

Case Report: A 7-year-old child underwent surgery at 6 years for undescendent testis. Intraoperative exploration shows two very small testis: the right one was fixed in the scrotum, the left one was left was fixed in the pubis. On examination, we found a normal penis of 6 cm and 2 non palpable testes. Karyotype: 46,XY. Hormonal balance shows: normal FSH and LH levels, low levels of testosterone < 0,025 ng/mL before and after HCG test, AMH < 0,01 ng/mL and surprisingly a normal level of inhibine B: 113 ng/mL controlled at 139 ng/mL. We seek first for an extragonadal production of Inhibine B but AFP and B HCG were normal. We though seek for the ELISA assay technique (of Beckman Coulter) and blood samples were adressed for a dosage using the less common ELISA technique of Anshlabs. Inhibin B was then found to be undetectable (<4,6 pg/mL). Fertility is thus found to be compromised. The child will receive a testosterone replacement therapy when aged 12 in addition to bilateral testicular prothesis.

Discussion: Heterophilic antibodies are present in a significant proportion of the population, and are likely to give a false-increased result in sandwich assays (such as the inhibin assay). They are thought to be produced following immunization with animal proteins (mouse, rabbit, goat, sheep etc.). In particular, a vaccine produced on rabbit cells had been the cause of false TSH results in the 1980s. This interference can be found nowadays in 1 serum/10 000.

Conclusion: Hormonal assays are often the diagnostic pivot in pediatric endocrinology. Being aware of biochemical causes of paradoxal hormonal dosages can be a key to avoid unecessary additional explorations.

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