Growth patterns and pubertal development in Down syndrome: A longitudinal and cross-sectional study

Abnormal growth is characteristic for patients with Down syndrome (DS), but the pathological factors contributing to short stature are not yet well known. We analyzed spontaneous growth pattern and pubertal development in 160 home-reared children with DS, aged between 3 months and 18 years, followed for a period of > 1 year (follow-up: 3.4 ± 1.9 years). In each subject we evaluated height (SDS), weight, bone age, bone age/chronological age ratio (BA/CA), weight excess (WE%), body mass index (BMI), onset of puberty and, in 25 cases, final height; in all of them we also checked thyroid function. Short stature was more evident in pubertal age. BA was constantly delayed in infancy but it increased progressively with age and pubertal stage. A trend to an early onset of puberty was observed in some patients with DS (mean age 11 ± 1.2 years for males and 10.2 ± 1.5 for females). Menarche occurred in 19 puberal females at 12.1 ± 1.2 years. Final height was always below the target height (p <0.0001). There was no significant difference in height between children with high TSH (n = 73) and those with normal TSH (n = 87). Obesity was present in 66% of puberals but only in 14% of prepuberals. Comparing age with WE and BMI a positive correlation was found. In conclusion, in DS BA increases faster compared to CA particularly in pubertal age. This peculiarity, sometimes associated with an early onset of puberty and a less evident pubertal growth spurt, can contribute to shorter final stature in these subjects. Obesity is sometimes present in childhood but it appears particularly evident after the onset of puberty.