What is the cause of mildly elevated prolactin (hyperprolactinemia)?

From the Guidelines

Mildly elevated prolactin levels are most likely caused by macroprolactin, a form of prolactin with low biological activity, and assessing baseline macroprolactin levels is recommended in cases of mildly or incidentally elevated serum prolactin 1.

Causes of Mildly Elevated Prolactin

The causes of mildly elevated prolactin levels can be varied, including:

• Certain medications, such as antipsychotics, antidepressants, and anti-nausea drugs 1
• Stress, hypothyroidism, kidney or liver disease, and nipple stimulation
• Physiological states like pregnancy, breastfeeding, and sleep
• Less commonly, pituitary microadenomas (small tumors)

Diagnosis and Management

When evaluating mildly elevated prolactin levels, it is essential to:

• Rule out medication effects by reviewing current prescriptions 1
• Check thyroid function with a TSH test
• Consider repeating the prolactin test after fasting and avoiding breast stimulation
• Assess baseline macroprolactin levels to determine the presence of macroprolactinemia 1

Importance of Macroprolactin Assessment

Macroprolactinemia is a common cause of mildly elevated prolactin levels, and its assessment is crucial to avoid unnecessary treatment and to determine the underlying cause of hyperprolactinemia 1.

Clinical Implications

In clinical practice, mildly elevated prolactin levels are often benign and may not require specific treatment if asymptomatic 1. However, it is essential to investigate the underlying cause of hyperprolactinemia to rule out any potential health risks.

Key Recommendations

• Assess baseline macroprolactin levels in cases of mildly or incidentally elevated serum prolactin 1
• Rule out medication effects and check thyroid function 1
• Consider repeating the prolactin test after fasting and avoiding breast stimulation 1

From the FDA Drug Label

As with other drugs that antagonize dopamine D2 receptors, RISPERIDONE elevates prolactin levels and the elevation persists during chronic administration. The cause of mildly elevated prolactin is RISPERIDONE treatment, as it elevates prolactin levels by antagonizing dopamine D2 receptors. 2

From the Research

Causes of Mildly Elevated Prolactin

• Prolactinoma, a type of pituitary tumor, is a common cause of chronic hyperprolactinemia 3, 4, 5
• Other conditions that can cause hyperprolactinemia include:
  • Primary hypothyroidism 3, 4
  • Drugs that elevate serum prolactin levels, such as antipsychotic medications like risperidone 3, 6
  • Stress 4
  • Renal failure 4
  • Idiopathic hyperprolactinemia, where the cause is unknown 4
• It is essential to exclude these conditions before making a diagnosis of hyperprolactinemia 3, 4, 7

Diagnosis and Treatment

• A careful history and examination, followed by laboratory tests and diagnostic imaging of the sella turcica, are necessary to determine the cause of hyperprolactinemia 3, 7
• Dopamine agonists, such as cabergoline, are the primary treatment for hyperprolactinemia 3, 5, 7
• Surgery may be an alternative treatment option in certain circumstances, such as when dopamine agonists are not effective or tolerated 3, 5, 7