Causes for Abnormal Lactation

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Abnormal lactation, also called galactorrhea, is milky nipple discharge that is usually not associated with normal milk production. It results from a number of medical conditions and medications and often goes away on its own. If abnormal lactation persists, treatment may be given to treat the underlying cause and prevent it from occurring again.

Medications and Supplements

Abnormal lactation can be caused by some medications and herbal supplements. High blood pressure medicines, antidepressants and tranquilizers have all been associated with galactorrhea. Hormonal birth control pills can cause hormonal changes that result in milky nipple discharge. Herbal supplements such as anise, fenugreek seed and fennel can also cause abnormal lactation.

Pituitary Tumors and Disorders

Pituitary tumors and disorders can cause levels of prolactin to increase, which can lead to abnormal lactation. Prolactinomas are benign pituitary tumors that increase prolactin production. According to the National Endocrine and Metabolic Diseases Information Service, this is the most common type of tumor that affects the pituitary gland. Hyperpituitarism, which is a medical condition resulting from an overactive thyroid gland, can also lead to the increased production of prolactin.


Hypothyroidism is a condition in which the thyroid gland does not produce enough hormones. According to the American Academy of Family Physicians, hypothyroidism causes increased production of a hormone that stimulates the release of prolactin. This is known as thyrotropin-releasing hormone. When production of this hormone increases, protein levels can also increase.

Chronic Kidney Disease

When the kidneys are functioning normally, they are responsible for clearing prolactin from the blood. In patients with chronic renal failure, the kidneys do not filter the blood properly, and prolactin levels may remain elevated. If prolactin levels remain high, abnormal lactation can occur. Professionals from the American Academy of Family Physicians indicate that 30 percent of people with chronic kidney failure develop elevated prolactin levels.

Nerve Damage

If breast tissue or the chest wall are injured in a motor vehicle accident or other trauma, the nerves of the nipple and breast can become damaged. Nerve damage can inhibit the secretion of hypothalmic prolactin inhibitory factor, which regulates prolactin levels in the body. This causes prolactin levels to become elevated, leading to abnormal milk secretion. Chest surgery, herpes zoster (shingles) and burns to the chest wall can also cause nerve damage that leads to galactorrhea.

Spinal Cord Injury

Spinal cord injuries that occur as the result of surgery or trauma can lead to abnormal lactation. In the August 1997 issue of the "American Journal of Obstetrics & Gynecology," Dr. William A. Faubion and Dr. Shahla Nader reported the case of a woman who developed galactorrhea after spinal cord surgery. The woman was not pregnant and should not have been producing breast milk. The researchers determined that injury to the spinal cord affected the nerves in the woman's endocrine system.

Excessive Breast Stimulation

Excessive breast stimulation also inhibits the release of hypothalmic prolactin inhibitory factor, causing galactorrhea in nonpregnant women. Excessive breast stimulation can occur due to sexual stimulation, frequent self-examinations of the breast, suckling or self-manipulation.