Bone Loss Associated with Hyperprolactinemia in Patients with Schizophrenia:Are There Gender Differences?Author(s): Bruce J. Kinon, Hong Liu-Seifert, Virginia L. Stauffer, Jayanthi Jacob
Background: Elevated prolactin (hyperprolactinemia) has been commonly reported during treatment with some antipsychotic drugs. A decrease in bone mineral density (BMD) may be related to elevated prolactin. The objective of this study was to determine the prevalence of low BMD in patients with schizophrenia treated with conventional antipsychotics or risperidone and to evaluate any potential relationship with treatment. Methods: A large-scale, crosssectional secondary analysis was performed to determine low BMD in schizophrenia patients (n=402) treated with conventional antipsychotics or risperidone for at least three months prior to study entry. BMD was determined by ultrasonography of the calcaneus. The potential effect of age, elevated prolactin, and duration of antipsychotic drug treatment on BMD was evaluated. Bone metabolism measures were determined and the potential effect of elevated prolactin and sex hormones on bone metabolism measures was also evaluated. Regression analysis was used for all the above analyses. Results: Low BMD was observed in about 1 in 4 female patients and 1 in 3 male patients. A negative correlation between T-score (BMD measure) and prolactin levels was found in male patients after controlling for age (p=0.05) and this correlation was not observed in female patients. Controlling for age, elevated prolactin was associated with elevated bone formation marker (osteocalcin) in both genders (female: p=0.03; male: p=0.05) and there was no significant correlation between change in T-scores and duration of antipsychotic drug for either gender. Total testosterone levels were negatively correlated with bone resorption marker (N-telopeptide) in men (p=0.04). Conclusions: Contrary to the trend in the general population with osteopenia, hyperprolactinemia during treatment with antipsychotic drugs may be associated with a greater prevalence of low bone mass in men compared to women. Elevated prolactin may have a direct effect on the bone, increasing bone turnover in patients of both genders, while hypogonadism may be associated with elevated prolactin in male patients only. Decreased testosterone levels due to hypogonadism in men may lead to increased bone resorption and subsequent low BMD.