Prevalence of hyperprolactinemia in schizophrenic patients treated with conventional antipsychotic medications or risperidone.

OBJECTIVE: The prevalence of hyperprolactinemia during treatment with conventional antipsychotic drugs or risperidone is under-recognized and requires further investigation. This open-label study was designed to determine the extent of this potential problem in a routine clinical setting.
METHODS: Four hundred and two adult inpatients or outpatients with a diagnosis of schizophrenia, schizophreniform disorder, or schizoaffective disorder were studied in a 1-day, point prevalence trial. Neither clinicians nor patients had any prior knowledge of serum prolactin levels or any potential associated adverse events, and patients were required to have been treated with a conventional antipsychotic drug or risperidone for a minimum of 3 months prior to study entry. Patients taking concomitant medications known to elevate prolactin were excluded. Rigorous assessment of serum prolactin was performed to estimate the prevalence rate of hyperprolactinemia, defined as a level above the upper limit of normal (>18.77 ng/ml for males, and >24.20 ng/ml for females). Patients were stratified within antipsychotic treatment by gender and, for females, by menopausal status.
RESULTS: Serum prolactin was obtained from 147 females (age range: 21-69 years; mean age=44.51 years) and 255 males (age range: 18-66 years; mean age=40.76 years). The prevalence of hyperprolactinemia among women of reproductive age (n=90) was 65.6% (mean serum prolactin=69.0 ng/ml), and among postmenopausal women (n=51), it was 45.1% (mean serum PRL=49.0 ng/ml). The prevalence of hyperprolactinemia across all males (n=255) was 42.4% (mean serum PRL= 32.4 ng/ml). The prevalence of hyperprolactinemia among females taking risperidone (N=42) was 88% versus 47.6% of those taking conventional antipsychotic drugs (N=105), with 48% of those females of reproductive age on risperidone experiencing abnormal menstrual cycles (secondary amenorrhea, oligomenorrhea, or polymenorrhea). Of all premenopausal females with hyperprolactinemia, 31.6% had estradiol levels <or=19.8 pg/ml (which is the mean estradiol level in postmenopausal female patients with normal prolactin). Across both genders, there were trends of low key reproductive hormone levels associated with prolactin elevations. Additionally, there was a trend correlation (p=0.064) between prolactin concentration and the risk of menstrual abnormality among females of reproductive age.
CONCLUSIONS: Hyperprolactinemia is very prevalent among women and men treated with conventional antipsychotic medications or risperidone. Due to the adverse effects associated with hyperprolactinemia, this likelihood should be seriously considered when choosing an antipsychotic suitable for the patient.