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Hyperprolactinemia is the presence of an abnormally high level of prolactin in the blood. Prolactin is a hormone produced by the pituitary gland. The numerous functions of prolactin in the body are mainly associated with pregnancy and the production of breast milk for the newborn. However, prolactin levels can rise when a woman is not pregnant or breastfeeding, causing a number of conditions that can affect normal menstrual function and fertility. Serum prolactin should only be measured in patients with a pituitary tumor or clinical symptoms and signs of hyperprolactinemia.
What is hyperprolactinemia
There are many causes of hyperprolactinemia, including certain medications and a pituitary tumor (prolactinoma). In order to prescribe the appropriate treatment, it is important to determine the underlying cause. Hyperprolactinemia can cause galactorrhea (excretion of breast milk outside lactation) and interfere with reproductive function. This can accelerate bone loss if it is due to a sex hormone deficiency.
Most prolactinomas are micro-prolactinomas. They usually don’t grow fast enough to cause severe complications. Patients with prolactinoma are usually treated successfully with dopamine agonists such as cabergoline.
Causes of hyperprolactinemia in adults
A high concentration of prolactin in the blood (hyperprolactinemia) is a fairly common endocrine disorder. Causes range from benign conditions that do not require treatment to serious medical problems that require immediate treatment. Hyperprolactinemia can also be a side effect of certain medications. To understand the essence of the ongoing processes, it is worth explaining a little the role of this hormone.
Prolactin is a polypeptide hormone synthesized and secreted by the lactotrophic cells of the anterior pituitary gland. Prolactin secretion is primarily regulated by dopamine, which is produced in the hypothalamus and inhibits prolactin secretion. The hypothalamic hormone thyrotropin-releasing hormone stimulates the secretion of prolactin.
Prolactin exerts its effects by binding to prolactin receptors. They are located on the cell membrane of many cells, especially in the breast and pituitary gland. In the breast, prolactin stimulates the growth of glands during pregnancy and the production of breast milk in the postpartum period. In the pituitary gland, prolactin suppresses the secretion of gonadotropin.
There are physiological, pathological and drug-related causes of hyperprolactinemia (high prolactin levels).
Physiological reasons. Pregnancy, breastfeeding and lactation, exercise, sexual intercourse and stress can increase prolactin levels. These increases are transient and usually do not exceed twice the upper limit of the normal ranges.
pathological causes. Prolactinomas are tumors arising from prolactin-secreting pituitary cells. Most prolactinomas (90%) are microadenomas (<1 cm in diameter) that are 10 times more common in women than in men. Microadenomas cause a mild increase in prolactin levels, which may be associated with symptoms of hyperprolactinemia, but they usually do not grow.
Macroadenomas (> 1 cm in diameter) are less common, and giant prolactinomas (> 4 cm in diameter) are rare. Compared to women, men are nine times more likely to develop macroadenoma. These tumors cause severe hyperprolactinemia – a prolactin concentration of more than 10 mIU/L almost always indicates a macroprolactinoma. They can cause hypopituitarism, visual field loss, or ocular paralysis by compressing the optic chiasm or cranial nerve nuclei.
Other formations of the hypothalamus and pituitary gland can also cause hyperprolactinemia. Since dopamine suppresses prolactin secretion, any neoplasm or infiltrative lesion that compresses the pituitary stalk can weaken the action of dopamine and cause hyperprolactinemia. However, stalk crush hyperprolactinemia is usually below 2000 mIU/L, which distinguishes it from macroprolactinoma.
Some diseases can cause hyperprolactinemia. Prolactin is excreted primarily by the kidneys, so kidney failure can increase prolactin levels. Because thyrotropin-releasing hormone stimulates prolactin secretion, hypothyroidism can also cause hyperprolactinemia. Seizures can cause a short-term increase in prolactin levels.
Reasons related to drugs. A number of drugs disrupt the release of dopamine in the hypothalamus, which leads to an increase in the secretion of prolactin (prolactin 500-4000 mIU / l). Hyperprolactinemia develops in patients taking antipsychotic drugs. It can also develop, to a lesser extent, due to certain selective serotonin reuptake inhibitors (drugs for depression). Other drugs may cause hyperprolactinemia less frequently. If hyperprolactinemia is caused by drugs, concentrations usually normalize if the drug is stopped within 72 hours.
Symptoms of hyperprolactinemia in adults
In some patients, hyperprolactinemia is asymptomatic, but an excess of the hormone can affect the mammary gland and reproductive function. In women, it can cause oligoamenorrhea (short and scanty periods), infertility, and galactorrhea. In men, hyperprolactinemia can lead to erectile dysfunction, infertility, and gynecomastia. Galactorrhea (excretion of milk or colostrum from the breast) is much less common in men than in women.
Gonadal hormone deficiency can accelerate bone loss. Patients may have symptoms or signs associated with the underlying cause of hyperprolactinemia. For example, headache and loss of vision in a patient with a pituitary tumor, and fatigue and cold intolerance in a patient with hypothyroidism.
Treatment of hyperprolactinemia in adults
It should be emphasized that prolactin levels should only be measured in patients with clinical symptoms or signs of hyperprolactinemia or in patients with a known pituitary tumor. The diagnosis of hyperprolactinemia can be based on a single measurement of serum prolactin above the upper limit of normal. Blood sampling should be performed without undue stress.
Diagnostics
Simple blood tests to measure the amount of prolactin in the blood can confirm the diagnosis of elevated prolactin levels. Prolactin levels above 25 ng/mL are considered elevated in non-pregnant women. Since every person experiences daily fluctuations in prolactin levels, it may be necessary to repeat the blood test if the level of the hormone is slightly elevated. Many women receive this diagnosis after being tested for infertility or complaining of irregular periods, but others have no symptoms. Sometimes patients have spontaneous milky discharge from the nipples, but most do not have this symptom.
A small increase in prolactin, in the range of 25-50 ng / ml, usually does not cause noticeable changes in the menstrual cycle, although it can reduce overall fertility. Higher prolactin levels of 50 to 100 ng/mL can cause irregular menstrual periods and significantly reduce a woman’s fertility. Prolactin levels greater than 100 ng/mL can alter the normal function of a woman’s reproductive system, causing menopausal symptoms (absence of menses, hot flashes, vaginal dryness) and infertility.
Once a diagnosis of hyperprolactinemia has been made, an examination should be performed to identify the underlying cause and associated complications. Women and men should measure estrogen and morning testosterone, respectively, along with gonadotropins. In women of childbearing age, thyroid and kidney function should be assessed and pregnancy excluded.
If no other clear cause is established, an MRI of the pituitary gland is indicated. Patients with a pituitary tumor larger than 1 cm in diameter should be screened to evaluate other pituitary hormones and check the visual field. It is important to determine bone mineral density in patients with hypogonadism.
Modern treatments
Some patients do not require treatment. Patients with physiological hyperprolactinemia, macroprolactinemia, asymptomatic microprolactinoma, or drug-induced hyperprolactinemia usually do not require treatment. If hyperprolactinemia is secondary to hypothyroidism, treatment of the patient with thyroxine should normalize prolactin levels.
Clinical guidelines
According to clinical guidelines, elevated prolactin levels are treated with a combination of several approaches.
Drugs that mimic the brain chemical dopamine can be successfully used to treat most patients with elevated prolactin levels. These drugs limit the production of prolactin by the pituitary gland and cause suppression of prolactin-producing cells. The two most commonly prescribed medications are cabergoline and bromocriptine. Starting with a small dose, which is gradually increased, side effects, including changes in blood pressure and mental fogging, can be minimized. Patients usually respond well to these medications and prolactin levels decrease after 2 to 3 weeks.
Once prolactin levels drop, treatment can be adjusted to maintain normal prolactin levels, and sometimes it can be stopped completely. Spontaneous tumor regression usually occurs within a few years without any clinical consequences.
In a small number of patients, drugs do not lower prolactin levels, and large tumors (macroadenomas) persist. These patients are candidates for surgical treatment (transsphenoidal adenoma resection) or radiation therapy.
Prevention of hyperprolactinemia in adults at home
Unfortunately, to date, no effective methods have been developed to prevent this pathology. Standard preventive measures are recommended, including maintaining a healthy lifestyle, giving up bad habits, treating any diseases of the reproductive sphere and hormonal metabolism.
Popular questions and answers
Regarding the diagnosis and treatment of the problem of the pituitary gland and high prolactin, the features of prevention, we talked with urologist, specialist in ultrasound diagnostics, doctor of the highest category Yuri Bakharev.