[A new way for the differential diagnosis of hypogonadotropic hypogonadism and constitutional delay of puberty in adolescent men aged 13.5-17 years].

Background: Differential diagnosis of hypogonadotropic hypogonadism (HH) and constitutional delay of puberty (CDP) is extremely important since with the latter puberty begins and completes without any medical intervention and in the case of HH puberty does not occur or is incomplete. Failure to start treatment on time leads to medical and psychosocial maladjustment of the patient.

Aim: Development of a method for differential diagnosis of hypogonadotropic hypogonadism and constitutional delay of puberty in boys 13.5-17 years old by scoring the levels of LH, FSH, testosterone and inhibin B.

Materials and methods: The study group was formed by adolescent men 13.5-17 years old with delayed puberty including all observations. Anamnesis, stage of puberty, testicular volume were assessed; serum levels of LH, FSH, testosterone (T) were determined by chemiluminescent analysis and inhibin B, AMH by ELISA. Stimulation tests were performed with triptorelin and human chorionic gonadotropin (3 days). Patients were followed up for 6-24 months.

Results: The study included adolescent men at the age of 13.5-17 years with delayed puberty: 56 for the purpose of development a method of differential diagnosis, 30 for its control (control group). We`ve created a method that allows differentiate HH and CDP. Through the ROC-analysis the most sensitive and specific HH markers were identified. The basal levels of LH, FSH, T, and inhibin B were selected as most available for outpatient testing. Based on the results of our own research and scientific data we selected ranges of values and rated LH, FSH, T and inhibin B depending on them (marks). Then we assigned the coefficients (k) for each hormone. Scores were calculated by multiplying the marks by k then summed and normalized to the maximum amount the patient could get. To increase the accuracy of diagnosis an age coefficient was introduced. The result of the calculation was the result of the scoring (S). S for CDP (10.65 [3.13-14.91]) differed significantly from that for HH (76.46 [57.79-83.74]) (p< 0.001). Diagnoses based on S (<21.16 and ≥55.07) in the control group were confirmed by follow up data in 97% cases. An algorithm for the differential diagnosis of HH and CDP by using S has been developed.

Conclusion: The result of scoring of LH, FSH, testosterone, inhibin B levels ≥55.07 makes it possible to diagnose hypogonadotropic hypogonadism, < 21.16 - constitutional delay of puberty with a high probability. In the case of score ≥21.16 but < 55.07, calculation of the inhibin B/AMH ratio and/or stimulation tests are required.