Serum prolactin level in patients taking olanzapine

Introduction: Olanzapine is a commonly used antipsychotic. Prolactin elevation is a common adverse effect of anstipsychotics, and serum prolactin elevation is seen in about 30% patients treated with olanzapine. There are confounding results about dose dependency of olanzapine and prolactin elevation, and also the duration of treatment. Method: Fifty six patients, 36 male and 20 female, who were taking olanzapine for any condition for more than a month at a constant dose were enrolled in the study. Patients’ age, weight, body mass index (BMI), serum prolactin levels, and some biochemical values were recorded. Patients were taken from the review outpatient department (OPD) after due consent. Results: Five each in male and female groups showed elevation of serum prolactin (estimated to be high if >20 ng/dl for males, and >25 ng/dl for females.) In females, the elevation was found at lesser dose of olanzapine (13 mg/day, in males 18 mg/day) and early in the treatment (2.4 months vs. 9.7 months in males). Males tended to show raised prolactin with higher doses of olanzapine (mean 18 mg/day). Females (26.31%) also showed higher prevalence of prolactin elevation compared to males (13.51%). No other parameter was found to modify the prolactin levels. Conclusion: Olanzapine causes elevation of serum prolactin, though lesser degree than some other antipsychotics. Females are more prone to have raised serum prolactin with olanzapine compared to males. However, the elevation seems to be transient. Higher doses of olanzapine tend to cause elevation of serum prolactin. Serum prolactin estimation in patients taking olanzapine may be undertaken to maintain quality life, particularly in females.