From the Guidelines
Patients taking risperidone can experience elevated prolactin levels, typically in the range of 25 to 100 ng/mL, which is considered acceptable if the patient remains asymptomatic. This medication-induced hyperprolactinemia is a known side effect of risperidone, as it blocks dopamine D2 receptors in the tuberoinfundibular pathway, removing dopamine's inhibitory effect on prolactin secretion from the pituitary gland 1. The normal prolactin level in non-medicated individuals typically ranges from 4-15 ng/mL for men and 4-23 ng/mL for women. However, in patients taking risperidone, prolactin levels can be significantly higher, often up to six times above the upper limit of normal, as reported in a study published in Nature Reviews Endocrinology 1.
Some key points to consider when evaluating prolactin levels in patients taking risperidone include:
- Monitoring for symptoms of hyperprolactinemia, such as menstrual irregularities, galactorrhea, sexual dysfunction, or gynecomastia, rather than focusing solely on the numerical value 1
- Regular prolactin monitoring, especially during the first few months of treatment 1
- Considering dose reduction, switching to a prolactin-sparing antipsychotic, or adding aripiprazole as an adjunct to reduce prolactin levels if symptoms become troublesome 1
- Being aware of other potential causes of hyperprolactinemia, such as primary hypothyroidism, chronic kidney disease, or severe liver disease, which can also affect prolactin levels 1
It is essential to note that the guideline development group recommends excluding confounding diseases that may cause hyperprolactinemia, and medications are one of the most common causes of hyperprolactinemia in adults 1. Therefore, clinicians should prioritize monitoring for symptoms and adjusting treatment as needed, rather than solely relying on prolactin level values.
From the FDA Drug Label
RISPERIDONE has been shown to elevate prolactin levels in children and adolescents as well as in adults [see WARNINGS AND PRECAUTIONS ( 5. 6)]. In doubleblind, placebo-controlled studies of up to 8 weeks duration in children and adolescents (aged 5 to 17 years) with autistic disorder or psychiatric disorders other than autistic disorder, schizophrenia, or bipolar mania, 49% of patients who received RISPERIDONE had elevated prolactin levels compared to 2% of patients who received placebo
The FDA drug label does not provide information on what is considered a normal prolactin level in patients taking risperidone. It only mentions that risperidone has been shown to elevate prolactin levels in children and adolescents as well as in adults 2.
From the Research
Normal Prolactin Levels
The normal prolactin level in patients can vary, but it is generally considered to be between 5-15 ng/mL for children and adults [@\1@, @\4@]. However, prolactin levels can be affected by various factors, including antipsychotic medication such as risperidone.
Risperidone-Induced Hyperprolactinemia
Risperidone is known to cause hyperprolactinemia, a condition characterized by elevated prolactin levels, in a significant number of patients [@\2@, @\3@, @\5@]. This can lead to various symptoms, including lactation, irregular menses, and fertility issues.
Treatment of Risperidone-Induced Hyperprolactinemia
Several treatment options are available for risperidone-induced hyperprolactinemia, including:
- Adjunctive aripiprazole [@\1@]
- Dopamine agonists such as cabergoline and bromocriptine [@\1@, @\2@, @\3@, @\4@]
- Metformin [@\1@]
- Herbal supplements [@\1@]
Key Findings
Some key findings related to normal prolactin levels in patients taking risperidone include:
- Cabergoline has been shown to be effective in reducing prolactin levels in patients with risperidone-induced hyperprolactinemia [@\2@, @\3@, @\4@]
- The normal prolactin level in patients taking risperidone can vary, but it is generally considered to be within the range of 5-15 ng/mL [@\1@, @\4@]
- Risperidone-induced hyperprolactinemia can have significant clinical effects, including impairment of somatic functions and reduction in quality of life [@\5@]