Study finds some people with DMD may not need long-term testosterone supplement after pubertal induction
Treatment with steroids (also called corticosteroids or glucocorticoids) is a routine part of Duchenne muscular dystrophy (DMD) care as it can reduce muscle inflammation and helps maintain muscle strength. There are two types of steroids prescribed for DMD - prednisolone and deflazacort.
While steroid treatment may also help the heart and lungs and reduce the development of a curved spine (scoliosis), there are a range of side effects. One side effect of steroid treatment is a delay in puberty, and most people on long-term daily steroids will need help to progress through puberty.
Testosterone is the male sex hormone that is produced in large quantities during natural puberty. It can be given in gradually increasing amounts to treat pubertal delay in DMD. Puberty is important for bone health and growth, general well-being and probably also helps muscle strength.
We know that a 2-year course of gradually increasing doses of testosterone by injection can take a young person with DMD through puberty, but the impact of long-term steroid use on androgen status (the levels of male sex hormones in the body) remains unclear.
Would young people with DMD benefit from continuing to receive testosterone once they have gone through puberty?
Study to understand if ongoing testosterone supplementation is required
A study funded by Duchenne UK sought to answer this question. It was undertaken by a team at the John Walton Muscular Dystrophy Research Centre and Institute of Genetic Medicine at the University of Newcastle. Led by Claire Wood, the study began in 2019.
Fifteen teenage boys with DMD who hadn’t gone through puberty were treated with a gradually increasing dose of testosterone for two years. The testosterone treatment was then stopped and they were reviewed at six months and then three years after their last injection.
At their final follow-up visit, the participants were an average age of 18.7 years old and had been treated with steroids for an average of 11.2 years.
What the study found
The study found that:
- Testicular volumes increased after the testosterone injections stopped (which suggests that the young men had started to produce their own testosterone) and some had normal testosterone levels which is promising regarding future fertility.
- One of the 15 participants needed to restart testosterone during the follow-up period and five were started on long-term testosterone treatment at the final visit, due to their levels being sub optimal (below what was thought good for them).
- There was a wide variation in testosterone levels between participants which suggests that some people may be more sensitive to the effects of steroid treatment on lowering testosterone levels and highlights the need for ongoing monitoring of testosterone levels in young adults with DMD.
The extended follow-up in this study highlighted the inevitable decline in muscle function and reduction in bone density that takes place during the loss of the ambulation phase (when people stop being able to walk) in DMD. Given the known additional advantages of testosterone on bone health, muscle and wellbeing, it will be important to continue monitoring testosterone levels in this population and offer supplementation as required if levels become too low.
The findings of the initial study (prior to this follow-up study) suggested that testosterone treatment improved muscle strength and possibly also reduced the underlying inflammatory process in DMD.
These benefits did not continue through the extended follow-up period, so it remains unclear whether testosterone injections give additional benefit to muscle bulk and inflammation in DMD above natural testosterone production, or whether the two year testosterone treatment was offered early enough halt the later muscle decline but only on a temporary basis. The research team would like to carry out further work in this area.
They will also be proposing that ongoing monitoring of testosterone levels are included in the next update of the standards of care for DMD.