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.
19 - 21 Sep 2019
European Society for Paediatric Endocrinology