Hyperprolactinemia is a Major Problem in Patients Treated with Antipsychotic Drugs

We have read with great interest the article “Relationship between plasma levels of prolactin and the severity of negative symptoms in patients with schizophrenia” written by Ates et al.. They aimed to investigate the relationship between prolactin levels of plasma and negative symptoms in patients with schizophrenia. They demonstrated that prolactin levels are positively correlated with the severity of negative symptoms. We would like to thank to the authors for their contribution of the present study, which is successfully designed and documented. In Ates et al’s article, the authors mentioned that gonadal steroids could play a significant role in the pathophysiology and could affect the course of schizophrenia. Additionally, it is known as classically, hyperprolactinemia is associated with disturbances in the levels of key reproductive hormones. For instance, Hyperprolactinemia inhibiting the effect of FSH and LH could decrease the levels of testosterone and estradiol. Although, there is a relationship between gonadal s t e r o i d s a n d b o t h h y p e r p r o l a c t i n e m i a a n d schizophrenia, researchers in this study did not consider the levels of testosterone, estradiol, FSH, and LH. Hence, the results might be different if the authors had mentioned those factors in their study. Prolactin exists in different forms in circulation as monomeric, dimeric, and polymeric. While the monomeric form, defined biologically active, constitutes the majority of total prolactin; the polymeric form defined macroprolactin and accepted biologically inactive is a complex of monomeric p r o l a c t i n w i t h I g G . M a c r o p r o l a c t i n e m i a i s characterized by excess of macroprolactin levels and seen 10-25% in patients with hyperprolactinaemia. This condition does not require any treatment, since it is not clinically significant. Another important issue in the differential diagnosis of hyperprolactinemia is to investigate the drug induced hyperprolactinemia such as metoclopramide, domperidone, and verapamil. This situation is quite often seen in clinical practice. Therefore, establishing of macroprolactinemia and drugs increasing the prolactin levels is quite important to avoid the misdiagnosis and overtreatments in patients with hyperprolactinemia. In conclusion, it is a pleasure for us to see that physicians not primarily involved in endocrinology field are also aware of hyperprolactinemia and its association with psychiatric disorders and medications. So, it would have been better if these additional crucial factors were included in the paper.