Hyperprolactinemia

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1- Introduction

2- Physiological  Overview

3- Symptoms

4- Treatment

Introduction

Hyperprolactinemia refers to higher-than-normal levels of prolactin hormone in the blood. Prolactin is typically associated with lactation in breastfeeding women, but it also has other functions in both men and women, such as regulating the immune system and behavior.

Physiological Overview

  • Regulation of Prolactin Secretion:

    • Prolactin secretion is primarily regulated by the hypothalamus-pituitary axis. Dopamine, a neurotransmitter, normally inhibits prolactin release from lactotroph cells in the anterior pituitary gland. This inhibition is tonic, meaning it is ongoing to prevent excessive prolactin secretion.

  • Causes of Hyperprolactinemia:

    • Prolactinoma: The most common cause of hyperprolactinemia is a prolactin-secreting adenoma (prolactinoma) in the pituitary gland. These tumors are usually benign and may lead to excessive prolactin secretion due to loss of normal inhibitory control by dopamine.
    • Medications: Certain medications, such as antipsychotics (especially older ones like phenothiazines), antidepressants (especially SSRIs), opioids, and some anti-nausea drugs, can interfere with dopamine signaling and lead to elevated prolactin levels.
    • Hypothyroidism: Low thyroid hormone levels can increase the production of TRH (thyrotropin-releasing hormone), which in turn stimulates prolactin secretion.
    • Pregnancy: During pregnancy, prolactin levels naturally rise to prepare for lactation.
    • Stress and Nipple Stimulation: Physiological factors such as stress or nipple stimulation can transiently increase prolactin levels.

  • Pathophysiological Effects:

    • Reproductive System: In women, hyperprolactinemia can disrupt the normal menstrual cycle (leading to irregular or absent periods) and suppress ovulation, causing infertility. It may also cause galactorrhea (abnormal milk production outside of breastfeeding).
    • In Men: Elevated prolactin levels can lead to decreased testosterone production, which can manifest as erectile dysfunction, decreased libido, and infertility. Gynecomastia (enlargement of breast tissue in males) can also occur.
    • Bone Health: Prolactin has been implicated in bone metabolism, and chronic hyperprolactinemia may contribute to bone density loss (osteopenia or osteoporosis) over time.
    • Other Effects: Elevated prolactin levels can sometimes cause headaches and visual disturbances if a large prolactinoma is present and causing pressure on surrounding structures within the brain.

Symptoms

    • In Women: Irregular menstrual periods or lack of menstruation (amenorrhea), abnormal milk discharge from the breasts not related to breastfeeding (galactorrhea), infertility.
    • In Men: Erectile dysfunction, decreased libido, infertility, enlarged breasts (gynecomastia).
    • Both Genders: Headaches, visual disturbances (if caused by a pituitary tumor).

Treatment

    • Medication: Dopamine agonists, such as cabergoline or bromocriptine, are often prescribed to reduce prolactin levels and shrink prolactinomas.
    • Surgery: Surgical removal of the tumor (if large or causing significant symptoms).
    • Management of Underlying Causes: If hyperprolactinemia is due to medications or other conditions, adjusting medications or treating the underlying cause may be necessary.
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