Growth hormone therapy in pre-pubertal children with Noonan syndrome: First year growth response and comparison with Turner syndrome

We studied the growth-promoting effect of treatment with recombinant human growth hormone in 23 prepubertal children with Noonan syndrome, aged between 5.4 and 14.3 y, and all with a height < 1.4 SD for Tanner standards. The growth response and skeletal maturation after 1 y of recombinant human growth hormone treatment (0.15 U/kg/day given by daily injection) in the Noonan syndrome patients was compared with the auxological changes observed in a group of 17 girls with Turner syndrome with a comparable age and height deficit who were treated with recombinant human growth hormone in a similar way. During 1 y of treatment, the mean ± SD height velocity increased by 4.0 ± 1.6 cm/y in the Noonan syndrome group and by 3.6 ± 1.3 cm/y in the Turner syndrome group. Height SDS for chronological age in the Noonan syndrome group increased by 0.53 ± 0.46 (p < 0.001). In the Noonan syndrome patients the changes in height velocity were positively related to birthweight (r = 0.48, p < 0.05). The changes in height velocity or height SDS were not related to the age, height deficit or a delay in bone age maturation at start of treatment. In neither the patients with Noonan syndrome nor Turner syndrome was an acceleration of bone maturation found. We conclude that treatment with recombinant human growth hormone in pre-pubertal NS patients induces an increase in height velocity and height SDS comparable to that observed in Turner syndrome girls.