Towards age-specific decision limits for the single-dose human chorionic gonadotrophin (HCG) stimulation test.

Abstract

Background-Aim: Human chorionic gonadotrophin (hCG) stimulation test is used to assess testicular function in children and adolescents with Differences in Sex Development (DSD). The assessment involves basal measurement of testosterone and dihydrotestosterone (DHT), followed by reassessment at 72 hours after a single intramuscular dose of hCG (1500 IU in < 2 years or 5000 IU in > 2 years). The current interpretation of post-hCG stimulation testosterone is not age- or Tanner stage-dependent. We aim to assess the necessity of age- and pubertal stage-related decision limits for this tet. Method(s): A retrospective descriptive study in the form of an audit of clinical and biochemical records of 75 karyotypic (46XY) boys with hypospadias/ micropenis/ bilateral undescended testes or androgen insensitivity, subjected to an hCG stimulation test, was conducted from June 2002 to December 2023. Testosterone and DHT were measured by High-Performance Liquid Chromatography-Tandem mass spectrometry (HPLC-MS/MS), and the results before 2013 by immunoassay (Beckman Coulter DxI800) were adjusted to HPLC-MS/MS based on a correlation study. Result(s): The ages of the boys included in the study ranged from < 1 month to 16.5 years. Post-hCG testosterone response was observed to be highly age-dependent. In < 6-month-old boys, post-hCG testosterone responses up to approximately 30 nmol/L were observed, while the maximum concentrations observed among older boys (6 months to 16.5 years) were only up to approximately 10 nmol/L. Further review by correlating the hCG-stimulation test responses with the complete clinical picture is required to determine the minimum testosterone level as the decision limit for an adequate response. Conclusion(s): It is apparent from this study that post-hCG testosterone response is highly age-related and thus warrants the application of age- or Tanner stage-specific decision limits for better accuracy in the diagnosis. As this is a relatively low-volume test, we recommend a multicentre collaborative study to obtain a larger number of data points completed with the clinical pictures to facilitate a more robust statistical analysis and derivation of decision limits.Copyright © 2024