Influence of olanzapine on serum prolactin levels and BMI in female patients with schizothrenia

Objectives: It has been well documented that elevation of serum prolactin (PRL) level and weight gain are common in patients receiving treatment with atypical antipsychotics. The existing evidences show that serum PRL is elevated in schizophrenic patients treated with olanzapine. However, little is known about the long-term effects of olanzapine on PRL levels and weight gain in female patients with schizophrenia. Materials and methods: This study addressed this issue by investigating the relationship between serum PRL level and body mass index (BMI). Seventy-nine female patients with first-episode schizophrenia were recruited and received olanzapine monotherapy for 12 weeks. Serum PRL level and BMI were measured at baseline and at 4, 8, 12 weeks. Thirty-five age-matched healthy female individuals were recruited as controls. The severity of psychiatric symptoms was evaluated using the Positive and Negative Syndrome Scale. Results: The olanzapine treatment for 12 weeks significantly increased serum PRL (P<0.01) level and BMI (P<0.01). A positive correlation between the pre- and posttreatment changes in serum PRL level and BMI was observed (r=0.247, P=0.028). Conclusion: Our findings suggest that PRL might conceivably modulate weight gain in female patients with schizophrenia receiving olanzapine treatment; however, the exact mechanism remains unclear.