Objective: Testosterone replacement is generally considered likely to be required only at testicular radiation doses in excess of 20Gy. Long-term data are not available for patients receiving 9-14.4Gy as part of Total Body Irradiation in childhood.
Design: Retrospective cohort study.
Data collection: notes review, laboratory results, prescription of testosterone.
Patients: Forty-two of 96 boys who received Total Body Irradiation (9-14.4Gy) and Haematopoietic Stem Cell Transplantation for childhood leukaemia at Great Ormond Street Hospital between 1981-2011 and survived >5 years.
Measurements: The serum concentrations of testosterone and gonadotrophins and the prescription of testosterone were recorded.
Results: Of the 42 boys included, 37 (88%) entered puberty spontaneously and 5 required induction. Median length of follow-up was 19.4 years (range 5-33.1). At last follow-up, 23 of the 37 (62%) with spontaneous puberty were receiving testosterone replacement and 4 of the 5 (80%) with induced puberty.
Conclusion: This study with the benefit of long follow-up indicates that Leydig cell failure occurs with radiation doses <20Gy. It may occur many years after irradiation and mandates long-term screening for hypogonadism.
Keywords: hematopoietic stem cell transplantation; leydig Cells; radiation; testis; testosterone; whole-body irradiation.
© 2019 John Wiley & Sons Ltd.