Elevated prolactin (differential)
Elevated prolactin can be due to a number of causes, including elevated production/secretion and reduced inhibition.
Prolactin is controlled by numerous homeostatic mechanisms, with tonic secretion of prolactin inhibitory hormone (dopamine) by the hypothalamus having a dominant effect 1.
Mechanical interruption of the portal transport of dopamine from the hypothalamus to the anterior pituitary gland (known as stalk effect) will reduce inhibition and thus result in minor elevation of prolactin.
Similarly, dopamine antagonists (such as the antipsychotic haloperidol and chlorpromazine ) as well as a long list of other drugs (including selective serotonin reuptake inhibitors (SSRI), monoamine oxidase inhibitors (MAO-I) and some tricyclic antidepressants), can cause hyperprolactinemia 1.
The highest levels of circulating prolactin are, however, encountered in the setting of prolactin secretion pituitary macroadenomas, especially those that are large and invading the cavernous sinus.
- 1. Torre DL, Falorni A. Pharmacological causes of hyperprolactinemia. Therapeutics and clinical risk management. 3 (5): 929-51. Pubmed