Prolactin

and Eva Rudolf-Müller, doctor

Valeria Dahm is a freelance writer in the medical department. She studied medicine at the Technical University of Munich. It is particularly important to her to give the curious reader an insight into the exciting subject area of ​​medicine and at the same time to maintain the content.

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Eva Rudolf-Müller is a freelance writer in the medical team. She studied human medicine and newspaper sciences and has repeatedly worked in both areas - as a doctor in the clinic, as a reviewer, and as a medical journalist for various specialist journals. She is currently working in online journalism, where a wide range of medicine is offered to everyone.

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Prolactin (prolactin) is an important hormone in the body. It is produced in the pituitary gland and, together with other hormones, ensures the production of milk in the mammary gland in mothers after birth. However, elevated prolactin levels can lead to infertility. Find out here what the prolactin value can tell you about your health.

What is prolactin?

The hormone prolactin (prolactin) is formed in the front part of the pituitary gland (pituitary gland) and reaches its place of action via the blood. This is primarily the female mammary gland: prolactin promotes its growth and, after childbirth, the production and secretion of breast milk. This is also indicated by the name: The term prolactin comes from Latin or ancient Greek and includes the word "lac" or "galaktos". Both mean "milk".

In addition, during pregnancy and breastfeeding, prolactin inhibits the menstrual cycle by preventing the release of various other hormones.

As a rule, prolactin is inhibited by the neurotransmitter dopamine. If the dopamine level falls during pregnancy, the prolactin level rises. After the baby is born, suckling the nipple causes prolactin to be released, so that sufficient milk is produced while breastfeeding and ovulation is still suppressed.

The function of prolactin in men is not yet known. Some experts suspect that the hormone here is responsible for the state of fatigue after orgasm.

When is the prolactin determined?

In women, the prolactin level is particularly determined in the following cases:

• unfulfilled desire to have children
• Suspected ovarian dysfunction
• increased flow of milk from the mammary gland outside of pregnancy and breastfeeding (galactorrhea)
• early puberty
• Virilization (masculinization)

In men, the prolactin level is checked if the doctor suspects impaired testicular function (hypogonadism).

Normal Prolactin Values

The prolactin level in the blood is determined from the serum. We recommend taking blood samples in the morning about four hours after getting up (taking into account day-night fluctuations). The following standard values ​​apply to adults:

	Normal prolactin range
Women of childbearing age	3.8-23.2 µg / l
men	3.0-14.7 µg / l

The following normal prolactin values ​​apply to women during pregnancy and after the menopause:

	Normal prolactin value
Pregnancy: 1st trimester	up to 75 µg / l
Pregnancy: 2nd trimester	up to 150 µg / l
Pregnancy: 3rd trimester	up to 300 µg / l
after menopause	up to 16.0 µg / l

In addition to "normal" prolactin, so-called macroprolactin is also found in the blood. This is an antibody produced by the body that has bound a prolactin molecule. Macroprolactin as such has no disease value and is harmless, but due to its size it greatly increases the measured values.

If an increase in prolactin is suspected, but this is not detected in the blood test, a metoclopramide test is carried out. This involves injecting the drug metoclopramide, which causes the hormone to rise. If the difference between the initial value and the second value is high, it is a hidden increase in the prolactin level (latent hyperprolactinemia).

When is the prolactin lowered?

The value is only lowered in rare cases. The reason can be a dysfunction of the pituitary gland (pituitary insufficiency) or the use of drugs that lower prolactin.

When is the prolactin increased?

Possible causes for an increased prolactin level (hyperprolactinemia) are:

• Prolactin-forming tumor (prolactinoma)
• Deficiency of dopamine (as an inhibitor of the increase in prolactin), for example in a pituitary tumor
• Medication (such as hormonal contraceptives, antidepressants, high blood pressure medication)
• Underactive thyroid (hypothyroidism)
• severe kidney failure (renal insufficiency), because prolactin is not excreted sufficiently but instead accumulates in the body
• in women: increased levels of male sex hormones

Hyperprolactinemia can also be functionally related: pregnancy and breastfeeding, but also physical and emotional stress, increase the prolactin level in the blood.

What to do when prolactin is increased or decreased

A lowered prolactin is only in very rare cases a disease. If a functional weakness of the pituitary gland can be ruled out as the cause, only the prolactin level is therefore checked regularly. The doctor will also check whether any medication you may have been taking is responsible for lowering prolactin.

If the prolactin is too high, the cause must be found through further tests and examinations and treated individually. For example, tumors of the pituitary gland are surgically removed. If the desire to have children is unfulfilled, medication can lower the increased prolactin to normal values.

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