Lexicon
Prolactin
Definition
Prolactin (PRL) is a polypeptide hormone produced by the lactotrope cells of the anterior pituitary gland whose principal physiological action is the initiation and maintenance of lactation. [1] [2] Hyperprolactinaemia is defined by a level of serum prolactin above the standard upper limit of the normal range and is a common finding in clinical practice. [3] Hyperprolactinaemia is a well-documented cause of infertility, and approximately 15 to 20% of women undergoing infertility evaluation have hyperprolactinaemia. [1]
How it works
Unlike other anterior pituitary hormones, the primary regulation of prolactin secretion is mediated through hypothalamic inhibition. [4] Elevated prolactin causes a reduction in sex hormone levels, and hyperprolactinaemia is among the most common causes of hypogonadotropic hypogonadism in both sexes. [5] [6] In the presence of high prolactin levels bone resorption is increased and bone formation is suppressed, and patients with hyperprolactinaemia often have decreased bone mineral density and an increased risk of fractures. [5] Testosterone replacement therapy can induce hyperprolactinaemia, with prolactin rising when replacement is started and falling when it is stopped, likely because exogenous testosterone is aromatized to oestradiol that stimulates prolactin release [7].
Connected concepts
How it's measured
The diagnosis of hyperprolactinaemia can be established by a single prolactin measurement without the use of stimulation or suppression tests, together with pituitary imaging. [4] [6] With immunoradiometric assays, falsely low prolactin levels are occasionally seen in patients with macroadenomas and very high serum prolactin, an artifact known as the hook effect, and all hyperprolactinaemic sera should be screened for macroprolactin. [4] With prolactinomas, prolactin levels generally parallel tumor size, and prolactin-secreting macroadenomas are typically associated with levels that exceed 250 microg/l. [4]
What levels mean
Normal serum prolactin levels vary between 5 and 25 ng/ml in females, and hyperprolactinaemia is usually defined as fasting levels above 20 ng/ml in men and above 25 ng/ml in women. [2] A level above the upper limit of normal, taken as 25 microg/l in women and 20 microg/l in men, raises suspicion of hyperprolactinaemia. [6]
Community knowledge
## Pituitary Microadenomas And Prolactin Faculty have discussed the shared pituitary origin of prolactin- and growth-hormone-secreting…
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- 1.Haidenberg-David F, Sidauy-Adissi J, Moscona-Nissan A, Jonguitud-Zumaya E, Fugarolas-Morinelli M, Martinez-Mendoza F, Taniguchi-Ponciano K, Marrero-Rodríguez D. Overview of Hyperprolactinemia: General Approach and Reproductive Health Implications. Arch Med Res · 2024
- 2.Majumdar A, Mangal NS. Hyperprolactinemia. J Hum Reprod Sci · 2013
- 3.Wildemberg LE, Fialho C, Gadelha MR. Prolactinomas. Presse Med · 2021
- 4.Chahal J, Schlechte J. Hyperprolactinemia. Pituitary · 2008
- 5.di Filippo L, Doga M, Resmini E, Giustina A. Hyperprolactinemia and bone. Pituitary · 2020
- 6.Auriemma RS, Pirchio R, Pivonello C, Garifalos F, Colao A, Pivonello R. Approach to the Patient With Prolactinoma.
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