Hyperprolactinemia as a Cause of Infertility
Hyperprolactinemia (high prolactin) at a glance
- Hyperprolactinemia occurs when a person’s bloodstream carries higher than normal levels of prolactin, the hormone responsible for breast milk production.
- The condition is not uncommon in women and men, causing infertility or subfertility (difficulty conceiving) in both sexes.
- In women, high prolactin can disrupt levels of reproductive hormones, leading to ovulation problems and irregular periods.
- Hyperprolactinemia can cause male infertility due to poor or no sperm production, low testosterone, erectile dysfunction and low sex drive.
- Prescription medications are most commonly used to treat hyperprolactinemia and help patients achieve pregnancy.
What is hyperprolactinemia?
Prolactin is a hormone made in the pituitary gland in the brain of both men and women. While the purpose of prolactin in men is not well understood, prolactin’s main function in women is to stimulate breast milk production during pregnancy after childbirth.
Hyperprolactinemia is the condition in which the pituitary gland in the brain produces higher than normal levels of prolactin. Too much prolactin in men and in women who aren’t pregnant can cause infertility in either. The condition also affects the levels of sex hormones in both men and women and in women can cause irregular periods.
High prolactin levels and female infertility
According to the American Society for Reproductive Medicine, hyperprolactinemia is present in roughly a third of childbearing-age women whose ovaries are normal but who have irregular periods.
Hyperprolactinemia causes disruption of a woman’s reproductive system by suppressing the gonadotropin releasing hormone (GnRH), which normally surges when it’s time for the female body to release an egg from an ovary. In turn, this diminishes the pituitary gland’s secretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH), the two hormones that stimulate egg growth and ovulation. This can result in anovulation, a direct cause of infertility, or inconsistent ovulation, which can cause or contribute to infertility.
High prolactin and infertility in men
In men hyperprolactinemia can hamper GnRH production as well, which in turn hinders the production of hormones that the pituitary makes to tell the testicles to make testosterone and sperm. As a result, sperm production and testosterone levels can fall. Low testosterone can cause an inability to maintain an erection during sex and reduce sex drive, which can both affect his ability to impregnate a partner.
Causes of hyperprolactinemia, including prolactinoma & issues with hormones
There are a number of potential causes for elevated prolactin, though no clear cause is found in about a third of cases. A growth or tumor on the pituitary gland called a prolactinoma is one such cause. The tumor, which can be large or small, can either secrete high levels of prolactin directly (functioning prolactinoma) or can cause indirect secretion (non-functioning pituitary adenoma) of high prolactin by compressing on the nearby cells in the pituitary gland that secrete prolactin. These tumors are almost always benign, or noncancerous.
Hyperprolactinemia can also be caused by certain medications including those used for high blood pressure, depression, heartburn, nausea, pain, birth control, menopause and serious mental health information.
Other causes include under active thyroid (hypothyroidism), chest-wall injuries, shingles, pregnancy and lactation, chronic liver and kidney disease, certain foods and herbs, nipple stimulation, and additional tumors or diseases affecting the pituitary gland.
Symptoms of elevated prolactin levels
Both men and women may experience:
- Reduced sex drive.
- Bone loss.
Women may also experience:
- Vaginal dryness.
- Missing or irregular periods.
- Breast discharge.
- Breast milk production when not nursing or pregnant.
Men may also experience:
- Erectile dysfunction.
- Low sperm count.
- Breast enlargement.
- Decreased body hair and muscle mass.
A fertility specialist will likely perform a physical examination to identify any obvious cause or breast discharge. Also, the doctor will order a blood test to measure prolactin levels. If a patient’s prolactin level in the blood is high, the doctor may order a retest as the patient fasts and after confirming that the patient is at the appropriate time in the menstrual cycle (in women) to check the level.
Prolactin levels are commonly higher after ovulation, so it is important to check a fasting level in the follicular phase of the menstrual cycle. A repeat level is also important to make sure that the initial elevation is not a transient abnormality.
If the level is slightly elevated and there is no obvious cause (such as pregnancy, nursing, medications or thyroid dysfunction), and there are no neurologic symptoms such as frequent headache or tunnel vision, then a fertility specialist may recommend medical treatment without formal brain imaging. If the levels are moderately to highly elevated, or if the patient has any significant neurological symptoms, then the specialist will likely recommend a study of the pituitary gland with a brain MRI.
Treatment of hyperprolactinemia depends on the cause of the condition. The goals of treatment might not be merely to bring the levels of prolactin to normal, but to ensure that the pituitary gland works properly, to shrink any tumor, and correct resulting issues, especially as they pertain to fertility.
If a person’s medications are causing the condition, other medications can be tried instead, or additional medications might be added to counter the effect. Cases caused by hypothyroidism can be treated with thyroid replacement medications.
If no cause is found or if the condition is due to a prolactinoma, medication is the usual treatment. Two dopamine agonist medications, one called bromocriptine (brand name Parlodel) and the other cabergoline (Dostinex), are used to lower prolactin levels, shrink tumors, decrease menstrual cycle irregularity and possibly minimize nipple milk discharge. In males these drugs can be used to improve the low testosterone and sperm production that can result from hyperprolactinemia.
These medications are commonly prescribed beginning at a low dose and increased until prolactin levels normalize. The medications will continue until the patient can achieve pregnancy when the normal menstrual cycles are resumed.
Treatment can also include surgery if the root cause is a tumor and medicines have not been effective. Radiation is rarely used but can serve as a back-up treatment if medicines and surgery have not been effective.
Once prolactin levels normalize with treatment, patients who were unable to become pregnant due to hyperprolactinemia alone are typically able to conceive.