Prolactin

Role of Prolactin in the Body

Prolactin is a hormone produced by the pituitary gland, playing a key role in the reproductive system and beyond.

Main Functions:

1. Lactation – stimulates milk production after childbirth.
2. Reproductive health:

• In women: influences the menstrual cycle, ovulation, and fertility.
• In men: involved in testosterone synthesis and spermatogenesis.

1. Immune regulation – modulates immune cell function.
2. Fluid and electrolyte balance – affects the kidneys (fluid retention).
3. Stress response – prolactin levels rise under stress, anxiety, and physical exertion.

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Symptoms of Prolactin Deficiency (Hypoprolactinemia)

Causes:

• Hypopituitarism (pituitary insufficiency due to trauma, surgery, or tumors).
• Use of dopaminergic drugs (levodopa, bromocriptine).

Symptoms:

• In women:
• Inability to breastfeed (lack of milk after childbirth).
• Menstrual irregularities (infrequent periods or amenorrhea).
• In men:
• Reduced libido, infertility (rare).
• General:
• Dry mucous membranes (due to reduced effect on fluid balance).

Important: Prolactin deficiency is rare and usually associated with generalized pituitary dysfunction.

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Symptoms of Prolactin Excess (Hyperprolactinemia)

Causes:

• Prolactinoma (benign pituitary tumor).
• Hypothyroidism (elevated TSH stimulates prolactin).
• Medication use (antidepressants, antipsychotics, antiemetics).
• Chronic stress, nipple stimulation, kidney failure.

Symptoms:

• In women:
• Galactorrhea (milk production outside of pregnancy and lactation).
• Menstrual irregularities (oligomenorrhea, amenorrhea).
• Infertility (due to suppressed ovulation).
• Reduced libido, vaginal dryness.
• In men:
• Gynecomastia (breast enlargement).
• Erectile dysfunction, reduced libido.
• Infertility (oligospermia).
• General:
• Headaches, visual disturbances (with macroadenoma).
• Osteoporosis (with prolonged elevation).

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Normal Prolactin Levels in Blood Tests

Levels depend on sex, age, and the laboratory.

Reference Values (µIU/L or ng/mL)*:

Group	Women (non-pregnant)	Men
Basal Level	60–500 µIU/L (3–25 ng/mL)	60–400 µIU/L (3–20 ng/mL)
Pregnant Women	Up to 10,000 µIU/L (500 ng/mL)	—
Postmenopausal	25–400 µIU/L (1–20 ng/mL)	—

*Conversion: 1 ng/mL ≈ 21 µIU/L

Important Notes:

• Prolactin is secreted in pulses, peaking at night and in the morning.
• The test should be taken on an empty stomach, in the morning, 2–3 hours after waking.
• Avoid before testing:
• Stress and physical exertion.
• Nipple stimulation, sexual activity.

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What to Do if Levels Are Abnormal

If Prolactin is Elevated:

1. Repeat the test (rule out stress or physical exertion).
2. Rule out hypothyroidism (TSH, free T4).
3. MRI of the pituitary gland (if prolactinoma is suspected).
4. Treatment:

• DopamineDopamine is a neurotransmitter and hormone that plays a key role in the brain's reward system, motivation, pleasure, learning, and movement regulation.Main functions: Stimulates feelings of pleasure and satisfaction. Involved in motivation and decision-making processes. Regulates motor activity. Affects memory, attention, and mood. agonists (bromocriptine, cabergoline).
• Surgery (for macroadenomas).

If Prolactin is Low:

1. Check other pituitary hormonesHormones are biologically active substances that are produced by specialized cells or glands (such as endocrine glands) and regulate various physiological processes in the body. They act as chemical signals that are transmitted through the bloodstream to organs and tissues to control and coordinate a wide range of functions, including metabolism, growth and development, reproduction, mood, and more. Examples include insulin, testosterone, estrogen, and adrenaline. (TSH, LH, FSH, cortisol).
2. MRI of the pituitary gland (if hypopituitarism is suspected).
3. Replacement therapy (if other hormone deficiencies are present).

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Conclusion

• Prolactin is a key hormone for lactation, reproduction, and stress adaptation.
• Excess causes infertility, galactorrhea, and reduced libido.
• Deficiency is rare but dangerous, leading to lack of lactation and hormonal imbalance.
• Normal range:
• Women: 60–500 µIU/L (3–25 ng/mL).
• Men: 60–400 µIU/L (3–20 ng/mL).