Altered interrelationship of dopamine, prolactin, thyrotropin and thyroid hormone in schizophrenic patients

Increased dopaminergic activity has been postulated to be one of the main causes of schizophrenia. To evaluate this hypothesis further, the interrelation between dopamine, prolactin, thyrotropin (TSH) and L-thyroxine was studied by determining their concentrations in the serum of ten acutely ill schizophrenic patients exhibiting distinct stages of process activity and ten healthy subjects. The level of dopamine was elevated in the sera of schizophrenic patients, whereas the levels of prolactin, TSH and L-thyroxine were decreased. On the basis of these results we hypothesize that 1. increased dopaminergic activity affects pituitary secretory function, and 2. decreased beta-adrenergic activity may be a consequence of decreased thyroid hormone concentration in plasma.