Elevated levels of growth-related hormones in autism and autism spectrum disorder

Summary 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.