Would a hematologist (heme)/oncologist prescribe testosterone to a patient with muscular dystrophy?

Testosterone Therapy in Muscular Dystrophy Patients

A hematologist/oncologist should not routinely prescribe testosterone to patients with muscular dystrophy unless there is documented testosterone deficiency, as testosterone therapy has not been shown to improve muscle strength despite increasing muscle mass. 1

Testosterone Deficiency in Muscular Dystrophy

• Hypogonadism is common in men with various myopathies, including muscular dystrophy, with studies showing approximately 54% of men with myopathies having low total testosterone levels 2
• Patients with muscular dystrophy, particularly myotonic dystrophy, often have low levels of circulating androgens 3
• Testosterone deficiency should be properly diagnosed through laboratory testing before considering treatment 4

Diagnostic Approach for Testosterone Deficiency

• Diagnosis requires both low testosterone measurements and presence of symptoms/signs 4
• Total testosterone level below 300 ng/dL on at least two early morning measurements is considered the threshold for low testosterone 4
• Luteinizing hormone (LH) levels should be measured to help establish the etiology of testosterone deficiency 4

Evidence on Testosterone Use in Muscular Dystrophy

• While testosterone administration has been shown to increase muscle mass in muscular dystrophy patients, randomized controlled trials have demonstrated no improvement in muscle strength 1
• A 12-month randomized, double-blind trial of testosterone in men with myotonic dystrophy showed increased muscle mass but no effect on any measurement of muscle strength 1
• Testosterone has been shown to increase muscle protein synthesis in myotonic dystrophy patients 3

Treatment Considerations

• If testosterone deficiency is confirmed, treatment should aim to achieve total testosterone levels in the middle tertile of the normal reference range (450-600 ng/dL) 4
• Commercially manufactured testosterone products should be prescribed rather than compounded testosterone 4
• Alkylated oral testosterone should not be prescribed due to risk of liver toxicity 4
• Intramuscular testosterone cypionate at 50-400 mg every 2-4 weeks is a standard replacement regimen for hypogonadal males 5

Risks and Monitoring

• Potential adverse effects include fluid retention, polycythemia, liver function abnormalities, and potential cardiovascular risks 5
• Testosterone therapy should not be commenced for 3-6 months in patients with a history of cardiovascular events 4
• Testosterone therapy has inhibitory effects on spermatogenesis and should not be prescribed to men trying to conceive 4
• Regular monitoring of testosterone levels, hematocrit, and liver function is necessary during treatment 4

Special Considerations for Muscular Dystrophy

• Adolescents with Duchenne muscular dystrophy on chronic glucocorticoid therapy often have profound pubertal delay, which may warrant testosterone supplementation 6
• In these cases, an incremental testosterone therapy approach may be used to induce puberty, but this is not yet part of standard care 6
• For adults with muscular dystrophy, the decision to treat should be based on documented testosterone deficiency rather than the muscular dystrophy diagnosis itself 2

Conclusion for Clinical Practice

• Hematologists/oncologists should refer patients with muscular dystrophy and suspected testosterone deficiency to appropriate specialists (endocrinology or urology) for evaluation 4
• If testosterone deficiency is confirmed, treatment may be considered for symptoms of hypogonadism but should not be expected to improve muscle strength 1
• The primary goal of testosterone therapy should be to address specific symptoms of hypogonadism rather than to treat the underlying muscular dystrophy 4