New insights into factors influencing adult height in short SGA children: Results of a large multicentre growth hormone trial

BACKGROUND: Growth hormone (GH) treatment is effective in improving adult height (AH) in short children born SGA. However, there is a wide variation in height gain, even after adjustment for predictive variables. It is therefore important to investigate new factors which can influence the response to GH. OBJECTIVE: To investigate the efficacy of GH treatment (1 mg/m(2/) day) in short SGA children on AH. To assess the relation between spontaneous catch-up growth after birth and growth during puberty on the total height gain SDS to AH. PATIENTS: Longitudinal GH trial in 170 children. RESULTS: Median age at start of GH was 7.1 years and height -3.0 SDS. AH was -1.8 SDS (TH-corrected AH -1.1 SDS) in boys and -1.9 SDS (TH-corrected AH -1.3 SDS) in girls. Spontaneous catch-up growth after birth was >/=0.5 SDS in 42% of children. In contrast to expectation, spontaneous catch-up growth was negatively correlated with total height gain SDS during GH (P = 0.009). During puberty, height SDS declined (-0.4 SDS in boys and -0.5 SDS in girls) resulting in a lower total height gain SDS than expected. Pubertal height gain was 25.5 cm in boys and 15.3 cm in girls, significantly lower compared to AGA children (P < 0.001). At onset of puberty, BA for boys and girls was moderately advanced (P = 0.02 and P < 0.001, respectively). Growth velocity was comparable to AGA children during the first two years of puberty, but thereafter significantly lower until reaching AH (P < 0.001). CONCLUSION: In contrast to our hypothesis, children with greater spontaneous catch-up growth after birth show a lower total height gain SDS during GH. Height SDS declines from mid-puberty, due to a marked early deceleration of growth velocity.