Objective  Children with autism are known to have larger head circumferences; whether they are above average in height and weight is less clear. Moreover, little is known about growth-related hormone levels in children with autism. We investigated whether children with autism were taller and heavier, and whether they had higher levels of growth-related hormones than control children did.

Design  A case-control study design was employed.

Patients  Boys with autism spectrum disorder (ASD) or autism (n = 71) and age-matched control boys (n = 59) were evaluated at Cincinnati Children's Hospital.

Measurements  Height, weight and head circumference were measured. Blood samples were assayed for IGF-1 and 2, IGFBP-3, growth hormone binding protein (GHBP) and for dehydroepiandrosterone (DHEA) and DHEA sulphate (DHEAS).

Results  Subjects with autism/ASD had significantly (P = 0·03) greater head circumferences (mean z-score 1·24, SD 1·35) than controls (mean z-score 0·78, SD 0·93). Subjects with autism also had significantly (P = 0·01) greater weights (mean z-score 0·91, SD 1·13) than controls (mean z-score 0·41, SD 1·11). Height did not differ significantly between groups (P = 0·65); subjects with autism/ASD had significantly (P = 0·003) higher body mass indices (BMI) (mean z-score 0·85, SD 1·19) than controls (mean z-score 0·24, SD 1·17). Levels of IGF-1, IGF-2, IGFBP-3 and GHBP in the group with autism/ASD were all significantly higher (all P ≤ 0·0001) than in controls.

Conclusions  Children with autism/ASD had significantly higher levels of many growth-related hormones: IGF-1, IGF-2, IGFBP-3 and GHBP. These findings could help explain the significantly larger head circumferences and higher weights and BMIs seen in these subjects. Future studies should examine the potential role of growth-related hormones in the pathophysiology of autism.