What is prolactin?
The hormone prolactin is produced in the anterior part of the pituitary gland (hypophysis) and reaches its site of action via the blood. This is primarily the female mammary gland: prolactin promotes its growth as well as the production and secretion of breast milk after birth. 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, prolactin inhibits the menstrual cycle during pregnancy and breastfeeding by preventing the release of various other hormones.
As a rule, prolactin is inhibited by the messenger substance (neurotransmitter) dopamine. If the dopamine level falls during pregnancy, the prolactin level rises. After birth, the baby’s sucking on the nipple causes prolactin to be released so that sufficient milk is produced during breastfeeding and ovulation continues to be suppressed.
The function of prolactin in men is not yet known. Some experts suspect that the hormone is responsible for the state of exhaustion after orgasm.
When is prolactin determined?
In women, the prolactin level is determined in the following cases in particular:
- unfulfilled desire to have children
- Increased milk flow 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).
Prolactin standard values
The prolactin level in the blood is determined from the serum. It is recommended to take a blood sample approximately four hours after getting up in the morning (taking into account day-night fluctuations). The following standard values apply for adults:
|
Prolactin standard range |
|
|
Women of childbearing age |
3.8 – 23.2 µg/l |
|
men |
3.0 – 14.7 µg/l |
The following prolactin standard values apply to women during pregnancy and after the menopause:
|
Prolactin normal 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 the 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 pathological value and is harmless, but due to its size it greatly increases the measured values.
When is prolactin low?
Only in rare cases is the level low. The reason may be a functional weakness of the pituitary gland (pituitary insufficiency) or the intake of medication that lowers prolactin.
When is prolactin elevated?
Possible causes of an elevated prolactin level (hyperprolactinemia) are
- Prolactin-producing tumor (prolactinoma)
- Lack of dopamine (as an inhibitor of the prolactin increase), for example in the case of a pituitary tumor
- Medication (such as hormonal contraceptives, antidepressants, high blood pressure medication)
- Underactive thyroid gland (hypothyroidism)
- Severe kidney weakness (renal insufficiency), because prolactin is then not excreted sufficiently but accumulates in the body
- in women: increased levels of male sex hormones
Hyperprolactinemia can also be caused by functional factors: pregnancy and breastfeeding, as well as physical stress and emotional strain, increase the prolactin level in the blood.
What to do if prolactin is elevated or low?
A low prolactin level is only pathological in very rare cases. 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 are taking is responsible for the prolactin reduction.
