Is testosterone therapy for boys with constitutional delay of growth and puberty associated with impaired final height and suppression of the hypothalamo-pituitary-gonadal axis?

We report the treatment of 44 boys with constitutional delay of growth and puberty (CDGP) at a mean chronological age of 14.3 years (range, 12.4–17.1) and bone age of 12.1 years (range, 9.1–15.0). All were below the 3rd height percentile for chronological age. They reccived monthly intramuscular injections of depot testosterone esters (50 mg) for a mean period of 0.35 years (range, 0.25–0.5). Means (SD) height velocity was 4.5 (1.5) cm/year during a pretreatment period of 0.5 years. During a period of 0.9 years which included the period of treatment with depot testosterone, mean growth velocity increased to 8.8 (1.9) cm/year (P<0.001). In the initial 1.8 years following the cessation of treatment growth velocity was sustained at 7.0 (1.7) cm/year. Pretreatment height standard deviation score (SDS) for bone age was –0.89 and this gradually reduced over the next 1.5 years to a minimum of –1.48. Thereafter, height SDS for bone age gradually increased to attain a value of –1.2, 3 years after the commencement of therapy (P<0.02). The same pattern of an initial decrease, followed by an increase, in height prediction was also observed when TW2 height prediction was analysed. Sexual maturation progressed during treatment, with mean testicular volume increasing both during and after treatment, confirming the diagnosis of CDGP. The time interval for progress through puberty was shorter in boys with testosterone therapy than in the normal population. The mean duration of puberty was 2.2 years compared to 3.3 years in normal boys. We conclude that low-dose depot testosterone treatment is safe and effective for boys with CDGP. At the dose regimen used there was no suppression of testicular enlargement. Initial decrease in height prediction concomitant with depot testosterone therapy may be misleading.