Hyperprolactinemia and Antipsychotic Therapy in Schizophrenic Patients with Hashimoto's Thyroiditis.

INTRODUCTION

Hyperprolactinemia (HPRL) is known as a side effect of some antidepressants and antipsychotics. These medicines are common in treatment of schizophrenia. Thus, HPRL is often observed in schizophrenic patients. It is also known that HPRL can occur in Hashimoto's thyroiditis due to prolactoliberin effect of thyroliberin. The clinical pathophysiology of the patients with the comorbidity of schizophrenia and Hashimoto's thyroiditis, receiving antipsychotics, is of special interest. It's fair to assume that these patients have higher risks of HPRL. To analyze risks of HPRL with antipsychotic treatment, to identify an association between the antipsychotic therapy (AT) and HPRL in Hashimoto's patients receiving AT, to explore the association of HPRL and other laboratory parameters in patients with Hashimoto's thyroiditis and schizophrenia during AT.

SUBJECTS AND

METHODS

We studied 17 patients with HT in comorbidity with schizophrenia receiving AT (mean age 46.5±12.8 years), all euthyroid or with light hypothyroidism. Different laboratory parameters such as anti-thyroid peroxidase (anti-TPO) and anti-thyroglobulin (anti-TG) antibodies, blood levels of thyroid stimulating hormone (TSH), free thyroxine (FT4), free triiodothyronine (FT3) and prolactin (PRL) were analysed.

RESULTS

The study revealed the high levels of PRL, anti-TPO and anti-TG autoantibodies. Thus, patients were classified into 3 groups by the degree of expected HPRL risk from the antipsychotics used: without expected risk, with low and high expected risks. The correlation analysis detected an inverse significant correlation (R=-0.51; p=0.037) between expected level of drug-associated HPRL risk and actual PRL levels in studied group. At the same time, we detected a positive significant correlation between the levels of PRL and FT4 in the groups (R=0.53; p=0.03). The correlations between the levels of PRL and other parameters such as TSH, FT3, anti-TPO, anti-TG, anti-TSH receptor antibodies were not statistically significant.

CONCLUSIONS

HPRL in the group was not associated with taking of antipsychotic drugs with high expected HPRL risk. Yet, a significant positive correlation existed between the levels of PRL and FT4. Hence, in Hashimoto's thyroiditis accompanied with treated mental illness there are some non-iatrogenic stimulants of prolactogenesis. It cannot be ruled out that antipsychotics may interfere with prolactin metabolism, which creates a false effect of a positive correlation between prolactin and free thyroxine levels, in contrast to common HPRL of hypothyroidism.