Endocrine Abstracts

Background: A recent study suggests that growth continues into the 20s in young men with Duchenne Muscular Dystrophy (DMD) following discontinuation of testosterone. There remains limited information on height and pubertal development in DMD following discontinuation of testosterone.

Aims: The aim of this retrospective study is to evaluate puberty and growth following discontinuation of testosteronein DMD.

Methods: A single observer (RS) measured the 19 tubular bones of the hand on radiographs performed for bone age assessment using the digital ruler. For each individual, mean for the 19 bones was calculated, referred to as the composite bone length. Descriptive data are expressed as median (range).

Results: Ten males had received testosterone for >12 months and had discontinued treatment. Two out of 10 reinitiated testosterone within 6 months of discontinuation due to identification of adult hypogonadism. In the remaining eight, hand radiographs were available prior to initiation of testosterone, whilst receiving and following discontinuation of treatment. All were on daily glucocorticoid. All eight were prepubertal (50% non-ambulant) prior to initiation of testosterone at median of 14.6 years (13.8, 15.3). At median of 16.7 years (15.8, 17.9) whilst still receiving testosterone (63% non-ambulant), 5/8 were at genital stage 3 and 3/8 were at genital stage 4 or 5. At median 18.9 years (18.3, 23.6) following discontinuation of testosterone for approximately 12 months (88% non-ambulant), all were at genital stage 4 or 5. A further two in these 8, had evidence of adult hypogonadism with follow-up, which is a total of 4 out of the ten in our cohort. Median composite bone length was 27.6mm (23.7, 31.9) prior to initiation of testosterone and was significantly lower than median composite bone length of 28.4 mm (23.8, 32.6) at last visit whilst on testosterone [P < 0.01] and median composite bone length of 28.2 mm (24.9, 33.0) following discontinuation [P < 0.001]. There was no significant difference between median composite bone length at last visit whilst on testosterone and following discontinuation.

Conclusion: Whilst testosterone therapy lead to satisfactory external virilization in DMD, adult hypogonadism was noted in 40% of young men in our cohort. Bone lengths on hand radiographs increased with testosterone therapy but showed no further increase following discontinuation of therapy.