Plasma growth hormone response to oral l-dopa in infantile autism.

In order to assess further the occurrence of hypothalamic dysfunction in infantile autism and its possible relationship to dopaminergic abnormalities, the l-dopa provocative test was performed in 22 patients fulfilling DSM-III criteria for this disorder. The results indicate a high incidence (at least 30%) of blunted plasma growth hormone (GH) responses following oral administration of l-dopa in this sample. These data suggest an alteration of hypothalamic dopamine receptor sensitivity in the patients with blunted responses. Thus, a subgroup of autistic patients within a descriptively homogeneous diagnostic category shows evidence of hypothalamic dysregulation and dopaminergic abnormalities.