Reduced thyroid-stimulating hormone response to thyrotropin-releasing hormone in autistic boys

The thyroid-stimulating hormone (TSH) and prolactin responses to thyrotropin-releasing hormone (TRH) were compared among four groups of boys--41 autistic, 12 mentally retarded (MR), 12 with minimal brain dysfunction (MBD) and five controls. The autistic boys were divided into two groups: DQ(IQ) greater than or equal to 80 and DQ(IQ) less than 80. Mean TSH basal and peak levels were significantly lower in both autistic groups than in the MR, MBD and control groups. Mean TSH peak value minus basal value (p-b) was significantly lower in both autistic groups than in the control group. Mean prolactin levels and p-b value did not differ among groups. It is suggested that there may be enhanced dopaminergic and/or reduced serotonergic activity in the central nervous system of autistic children, together with hypothalamic dysfunction.