While the APA guidelines recommend monitoring prolactin levels only when clinically indicated (3), other guidelines suggest that baseline prolactin levels should be measured routinely if a patient is starting antipsychotic therapy and that a reassessment should be performed after three months of treatment if there are symptoms of hyperprolactinemia or if the patient is receiving an antipsychotic with known prolactin-elevating properties (23). This evidence concerns the gene PRL and hyperprolactinemia.