PROLACTIN TEST
Prolactin is a hormone produced by the pituitary gland which sits at the bottom of the brain. Prolactin hormone causes breasts to grow and develop and causes milk to be made after a baby is born.
Both men and women have small amounts of prolactin in their blood. The levels of Prolactin are controlled by other hormones called prolactin inhibiting factors (PIFs), like dopamine. Prolactin levels go up during pregnancy, after the baby is born, there is a sudden drop in estrogen and progesterone. The high prolactin levels trigger the body to make milk for breastfeeding. Prolactin helps regulate the menstrual cycle (periods) in women who aren’t pregnant. In men, prolactin affects production of sperm.
WHAT IS HYPERPROLACTINEMIA?
Hyperprolactinemia is relatively common in women. It is a condition of too much prolactin hormones in the blood of women who are not pregnant and in men. When this happens, a woman might have trouble getting pregnant or her breasts may start producing milk outside of pregnancy (galactorrhea). A vast majority of women with galactorrhea also have hyperprolactinemia. High prolactin levels interfere with the normal production of other hormones, such as estrogen and progesterone. This can change or even stop the release of an egg from the ovary (ovulation). It can also lead to irregular or missed periods.
Some women have high prolactin levels without any symptoms.
In men, high prolactin levels can cause galactorrhea, inability to have an erection during sex (impotence), reduced desire for sex, and infertility. A man with untreated hyperprolactinemia may make less sperm or no sperm at all.
CAUSES OF HYPERPROLACTINEMIA
Some common causes are:
- Certain foods
- Nipple stimulation
- Pituitary tumors (prolactinomas)
- Underactive thyroid (Hypothyroidism)
- Medicines given for depression, psychosis, and high blood pressure
- Some Herbs, e.g. fennel seeds, and red clover
- Irritation of the chest wall (e.g. surgical scars, or a tight bra)
- Excessive Stress or extreme exercise
- No cause is found in about a third of all cases of hyperprolactinemia.
WHY GET TESTED?
In men; the test helps to diagnose the cause of decreased libido and/or erectile dysfunction; to detect and monitor a pituitary tumor that produces prolactin (prolactinoma)
In women; to help investigate unexplained flow of breast milk (galactorrhea), abnormal nipple discharge, absence of menstrual periods, and/or infertility.
HOW HYPERPROLACTINEMIA IS TESTED
Blood tests can measure levels of prolactin. The levels are sometimes higher if the patient just had a meal or is under stress. The test may be done again after a period of fasting and patient is relaxed. Our doctor may also perform a physical exam to find any obvious causes or any breast discharge.
The doctor may order a magnetic resonance imaging (MRI) scan of the brain to check for a tumor of the pituitary gland if levels are still high after the second check.
WHAT DOES THE TEST RESULT MEAN?
Normally, men and non-pregnant women will have only small amounts of prolactin in their blood. Prolactin levels however needs to be evaluated. This evaluation will be based on the time of day that the samples are collected. The levels will vary over a 24-hour period, rising during sleep and peaking in the early morning. Ideally, a person's blood sample should be drawn 3 to 4 hours after waking up.
During pregnancy and after childbirth while the mother is nursing a high level of prolactin is normal.
A high level of Prolactin may also be seen with a few other conditions, such as:
- The eating disorder anorexia nervosa
- Tumors that produce and release prolactin
- Kidney disease
- Polycystic ovary syndrome
- Diseases of the hypothalamus
- Underactive thyroid (hypothyroidism)
- Liver disease
- Other pituitary diseases and tumors
Low levels of prolactin below normal are not usually treated but may indicate a general decrease in pituitary hormones caused by hypopituitarism (a pituitary disorder). A common cause of low levels is medication. Some examples include dopamine and levodopa. In some cases, low levels of prolactin may be a sign of a pituitary disorder, for example, hypopituitarism a rare condition that can delay growth and puberty in children, and cause premature aging in adults.
OTHER TESTS MAY BE DONE TO EVALUATE AN ELEVATED PROLACTIN?
Depending on the purpose for the test, other tests may be done to evaluate high prolactin. These include:
- Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) tests - To help evaluate ovulation and fertility
- An eye examination - To evaluate problems with vision
- Testosterone test - Levels will usually be low in a male when prolactin is high
- An MRI of the brain - To show pituitary enlargement and help locate a tumor
Elevated prolactin levels require further laboratory tests to ensure that the elevation is not due to macro prolactin.
High levels of prolactin may indicate an underlying health condition. Higher levels are normal in pregnant women and those who are breast-feeding.
The test to measure prolactin levels is simple and can help doctors to prescribe the correct medication kin order to reduce levels or provide treatment for an underlying condition that may be causing the high levels.
