Pubertal growth in response to testosterone replacement therapy for radiation-induced Leydig cell failure

The adolescent growth pattern of eight boys, who had puberty induced with androgen replacement therapy following radiation-induced Leydig cell failure, was studied from induction of puberty at a mean age of 13.1 years (range 11.6-14.5) to final height at mean age of 18.8 years (range 17.7-20.3). The mean gains during puberty (SD) for standing height, sitting height, and sub-ischial leg length were 18.56 cm (3.98), 10.46 cm (2.39), and 8.1 cm (2.01) respectively, which were significantly reduced compared with normal Tanner standards (P < .001). The peak velocity for each parameter occurred in the 1st year of induced puberty in contrast to the pattern in normal adolescence, although the mean peak velocity for each auxological parameter was not significantly different from the normal Tanner standards. The mean adult standing height (SD), 167.5 cm (9.88), and mean adult leg length (SD), 80.8 cm (6.19), were not significantly different from the normal Tanner standards, whereas the mean adult sitting height (SD), 86.7 cm (4.78), was shorter (P < .001). Three of the eight patients had a leg length standard deviation score less sitting height standard deviation score in excess of +2.96 suggesting the presence of significant skeletal disproportion. Seven of the eight boys reached target genetic height, though in six, the final height was below mid-parental height (P < .05). The modest loss in height potential was mainly due to radiation-induced skeletal dysplasia attenuating the growth of the spine. The families of boys with radiation-induced Leydig cell failure requiring androgen replacement therapy can be reasonably optimistic about height prognosis as seven of the eight boys reached target genetic height.