Testosterone Therapy for Pubertal Delay in Duchenne Muscular Dystrophy

"Observational study of clinical outcomes for testosterone treatment of pubertal delay in Duchenne Muscular Dystrophy" is a single centre observational study that aims to follow the progress of 20 adolescents with Duchenne Muscular Dystrophy (DMD) and delayed puberty who are treated by the Newcastle muscle team, as they are treated with testosterone to induce puberty. The participants will all be treated with the standard stepwise regimen of testosterone injections every 4 weeks and data will be collected to help determine the effectiveness and tolerability of the current treatment regimen. The investigators will use the data to explore the effect of testosterone on pubertal development, growth, muscle strength and function, bone mineral density and body composition and characterise any side effects. Semi-structured interviews will also be carried out to learn the boys' views on the tolerability of the regimen. The study will last up to a maximum of 27 months in total for each participant, but may be less if they are happy with pubertal development before this time. It is important to do this study because from the investigator's limited experience in this group, testosterone treatment seems to be well liked and tolerated but the best treatment regimen to use remains unknown and there is no current consensus. It is not currently part of the standard of care in DMD but it would be important to include it if this study can show that it is an effective treatment for pubertal delay.