Short-term growth in children with growth disorders

Objective: We have previously demonstrated that normal prepubertal growth over 1 year is composed of growth spurts lasting an average of 8 weeks, separated by periods of very slow growth or stasis. We have now analysed short-term growth patterns in eight children with different growth disorders: Turner syndrome (n = 2), intrauterine growth retardation (IUGR, n = 1) and growth hormone (GH) deficiency (GLAD, n = 5). Methodology: Height was measured daily in the morning by parents over 4-12 months. Regression and time series analysis were used to characterize short-term growth. In two boys (GHD and IUGR) their normal twin brother was measured in parallel. Results: All height velocity curves, based on regression analysis, showed a biphasic pattern, characterized by growth spurts of varying amplitudes and periods of very slow growth or growth stasis. When compared to growth curves in normal children, the principal qualitative differences in GHD and Turner syndrome were increased stasis time and reduced growth spurt amplitude. In IUGR reduced amplitude and length of growth spurts were seen, but the time spent in stasis was similar to normal children. Two naive patients with GHD increased the amplitude of their growth spurts by a mean 0.013 cm day^-1 on GH treatment, with the mean length of their growth spurts increasing by 10 days. Their time spent in stasis decreased from 19% to 6% on GH. In two subjects with GHD the growth pattern during maintenance GH treatment was similar to that seen in normal children. Using time series analysis significant periodicities in height measurements were seen in the majority of children with growth disorders, which disappeared in patients with GHD in the catch-up phase after commencing GH therapy. Conclusions: (1) The growth spurts and stases seen in normal children are also observed in those with growth disorders, (2) different growth disorders have variable effects on the spurt-stasis model of childhood growth, (3) catch-up growth on GH in children with GHD was achieved by increasing the amplitude of the growth spurts and reducing the time spent in stasis.