IMPE Abstracts

Introduction: To assess testicular function, in patients with differences in sexual development (DSD), the Leydig cell stimulation test with human chorionic gonadotropin hormone (hCG) is performed and testosterone production is measured. There is no uniformity in terms of hCG dose or duration of stimulation. At the National Institute of Pediatrics (INP), this test is performed with 10,000 IU IM, for 4 consecutive days, and a daily sample of testosterone is taken, which are processed together on the 5^th day.

Objective: To determine the minimum dose of hCG necessary to generate an increase in serum testosterone concentration > 100 ng/dl.

Materials and methods: It is an observational, longitudinal, analytical and retrospective study. All records of patients aged 0 to 18 years, diagnosed with DSD and hCG test during 1990-2020 were reviewed. The patients were divided by age groups. The frequency and concentration of testosterone with doses of 2500, 5000, 7500 and 10000 IU of hCG were analyzed. A positive test was considered when the serum concentration of testosterone was greater than 100 ng/dl.

Results: 196 patients who met the inclusion criteria were analyzed, 71% were less than 2 years old at the time of the study, 21% between 2 and 9 years old and 7% more than 9 years old. The most frequent karyotype was 46 XY. A positive response was found with the 5000 IU dose of hCG in 72% of patients under 2 years of age, with a testosterone concentration of 138.5 ng/dl (sensitivity 86%). However, in the group 2 to 9 years old, the same dose of hCG only achieved a positive response in 19.5% (sensitivity 33%), and a dose of 7500 IU of hCG was required to observe a positive response in 53% of the patients. The 52% of patients younger than 6 months had a basal testosterone concentration >100 ng/dl.

Conclusion: We identified that the minimum dose to generate a positive response in most of the patients under 2 years of age, was 5000 IU of hCG. Patients older than 2 years may require an additional dose of hCG. It is necessary to know the basal testosterone before indicating stimulation with hCG, especially in children younger than 6 months.