Hyperprolactinemia (High Prolactin) Causes
Normal ovulation is a complex process that requires many things to happen properly and at the correct time with the proper hormone levels. Often subtle hormonal imbalances or ovulation abnormalities result in decreased fertility. One hormone imbalance that can affect fertility is prolactin levels. Excessive prolactin levels in nonpregnant women is known as hyperprolactinemia.
Prolactin is a hormone secreted by the pituitary gland, located at the base of the brain. In nonpregnant women, in circulates in low levels in the bloodstream. When a woman is pregnant the numbers increase tenfold and stimulate milk production. Hyperprolactinemia can create several problems including:
- inadequate progesterone production during luteal phase after ovulation
- irregular ovulation and menstruation
- absence of menstruation
- galactorrhea (breast milk production in non-nursing woman)
Prolactin testing is usually performed in females in the morning at the beginning of the cycle and again seven days later to determine if the prolactin levels are normal. Normal prolactin level in women is approximately 25 nanograms per milliliter. High levels of prolactin my indicate the need for further testing (MRI) to check for a pituitary tumor.
Hyperprolactinemia is a fairly common problem, found in up to one-third of all infertility patients who do not menstruate. There are several known causes of excessive prolactin. Surgical scars on the chest wall or other chest wall irritations like shingles can trigger a rise in levels. According to the American Society of Reproductive Medicine, some medications, like tranquilizers, high blood pressure medications and anti-nausea drugs can all lead to such problems. Oral contraceptives and recreational drugs like marijuana may result in mild cases. Some women with PCOS also have hyperprolactinemia.
The most common cause of hyperprolactinemia is hypothyroidism, in which an inadequate amount of the thyroid hormone is produced. Treating the hypothyroidism with thyroid hormone can correct prolactin levels. In rare cases, there are other problems, such as chronic kidney failure or tumors of the pituitary gland may also by the culprit. They can usually be identified with an MRI. However, in about 30 percent of the cases, the root cause is unexplained.
The drug usually prescribed to treat prolactin excess is Bromocriptine (Parlodel ®). It suppresses the prolactin production, with a starting oral dosage of 1.25 to 2.5 mg a night, with the dosage increasing until levels are normal. Ovulation and menstruation generally return about six weeks after beginning the medication. It is continued until pregnancy occurs. It is also used to treat pituitary tumors. Unfortunately, prolactin levels usually rise again when medication is discontinued.
Side effects are mild and generally subside within a month. Lightheadedness, nausea and headaches are the most common side effects. Others include nasal congestion, dizziness, constipation, fatigue, vomiting and rarely, hallucinations. Side effects can be minimized when the dosage is slowly increased, allowing the woman to develop tolerance to the medication. It may also be helpful if administered vaginally. The cost for a thirty day supply for 2.5 mg is about $60, and $100 for 5 mg a day.
For those not wishing to become pregnant, physicians may choose simply to monitor levels as needed.
1. Gregorius, G. et al; Evaluation of Serum prolactin levels in patients with endometriosis and infertility. (Gynecol Obstetr Invest, 1999)
2. Spitzer, M. et al; Pattern of development of hyperprolactinemia after initiation of haloperidol therapy. (Obstet Gynecol, 1998, May)
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