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Prolactin Deficiency - Causes, Symptoms, and Treatment

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Prolactin is a hormone that helps the breasts prepare for lactation and produce milk. Read to know the causes and effects of prolactin deficiency.

Medically reviewed by

Dr. Sunita Kothari

Published At August 17, 2022
Reviewed AtDecember 1, 2023

What Is Prolactin and Its Function?

The hormone prolactin, often known as milk hormone, produced by the pituitary gland, located near the base of the brain, is responsible for breast growth. Prolactin is also known as luteotropic hormone (LTH) or luteotropin. After a baby is born, prolactin is responsible for breastmilk production. It also has a variety of additional functions in the body, including controlling the immune system and acting on the reproductive system. The pituitary gland produces the majority of prolactin. Prolactin is also produced by the central nervous system, immunological system, uterus, and mammary glands. Prolactin production can also be triggered by nipple stimulation, exercise, and stress.

Functions of Prolactin -

Prolactin is involved in hundreds of body functions, but its two most important functions are -

What Is Prolactin Deficiency?

Hypoprolactinemia is a condition with too little prolactin in the blood. This is an extremely unusual condition that can occur in persons who have pituitary underactivity. After childbirth, a decreased prolactin secretion can result in insufficient milk production. Although preliminary data suggest that people with low prolactin levels may have impaired immune responses to certain infections, most people with low prolactin levels do not have any specific medical concerns.

What Are the Causes of Prolactin Deficiency?

Medical treatment is rarely required when prolactin levels are low. Prolactin levels can fall below normal in the following conditions -

  • Sheehan's Syndrome - A pregnant woman's anterior pituitary gland is partially or entirely destroyed during or shortly after childbirth. This syndrome is more common in women who have experienced severe bleeding during delivery. Affected women do not produce breast milk and are unable to breastfeed their children.

  • Postpartum pituitary necrosis and other forms of anterior pituitary dysfunction are the most common causes of prolactin deficiency.

  • Hypopituitarism - Pituitary gland not functioning properly. It is due to the inability of pituitary lactotrophs to release prolactin.

  • Hypoprolactinemia is as prevalent as hypopituitarism in general.

  • Low levels of prolactin can be caused by some medications like -

    • Dopamine.

    • Levodopa.

    • Ergot alkaloid derivatives.

    • Pyridoxine.

    • Diuretics.

  • Nicotine - Mothers who smoke have less milk production due to prolactin deficiency.

  • Prolactin can be suppressed by retained placental fragments in the peripartum interval.

  • Albright Hereditary Osteodystrophy - G-protein mutations are linked to prolactin deficiency.

  • Multiple Pituitary Hormone Deficiencies (MPHD) - A rare genetic disorder.

What Are the Symptoms of Prolactin Deficiency?

Although prolactin deficiency is very rare, the following are some of the common symptoms -

  • Inadequate lactation (puerperal alactogenesis).

  • Menstrual disorders.

  • Infertility and subfertility.

  • Delayed puberty.

  • Decreased spermatogenesis and decreased testosterone production in males.

How Is Prolactin Deficiency Diagnosed?

  • Prolactin Level Test - Blood samples are taken from the patient and sent to the lab to check levels of prolactin. The normal values of prolactin are as follows -

    • Males: 2 ng/mL to 18 ng/mL.

    • Nonpregnant Females: 2 ng/mL to 29 ng/mL.

    • Pregnant Females: 10 ng/mL to 209 ng/mL.

  • Magnetic resonance imaging (MRI) - If pituitary dysfunction or tumor of the pituitary gland is suspected.

What Is the Treatment for Prolactin Deficiency?

  • The treatment or management of prolactin deficiency may involve the following measures -

  • Medical Care - Formula or bottle-feeding is often indicated for women with puerperal hypoprolactinemia and low milk supply. Drugs that boost milk production are often ineffective.

  • Medication - There is currently no treatment for prolactin deficiency. Antidopaminergic drugs that disrupt prolactin's dopamine-induced hypothalamic inhibitory regulation may help with insufficient lactation.

    • Hypoprolactinemia-related subfertility can be treated with Clomiphene citrate or gonadotropins.

    • Antidopaminergic drug Metoclopramide has shown to increase milk yield in women with inadequate lactation. These disrupt the hypothalamic dopamine-induced inhibitory regulation of prolactin.

  • Patient Education - Educate the patient about the possibility of not being able to breastfeed her baby if hypoprolactinemia is diagnosed.

What Happens if Prolactin Levels in the Blood Are Too High?

High prolactin levels

Hyperprolactinemia is a condition in which too much prolactin is in the blood. The most common causes include pregnancy, drugs that inhibit dopamine action in the body, thyroid underactivity, and benign pituitary tumors (known as prolactinomas).

It can lead to the following symptoms -

  • In Females -

    • Unwanted milk production (even when not pregnant or breastfeeding).

    • Menstrual cycle irregularities.

    • Symptoms of estrogen deficiency.

    • Vaginal dryness causes painful sexual intercourse.

    • Galactorrhea (milky nipple discharge).

  • In Males -

    • Erectile dysfunction.

    • Low serum testosterone level.

    • Lack of sexual desire.

    • Muscle mass and body hair loss.

    • Gynecomastia (enlarged breasts).

    • Infertility.

What Are Causes of High Levels of Prolactin in Blood?

The prolactin level may rise due to the following causes -

  • Hypothyroidism or underactive thyroid.

  • Prolactinoma (a hormone-secreting pituitary tumor) - It is a benign growth on the pituitary gland. Headaches, vision abnormalities, and signs of other pituitary hormone deficiency are also common symptoms and indicators of prolactinomas.

  • Medications given for depression, hypertension, or psychosis.

  • Herbs like fennel, fenugreek, or red clover.

  • Habits like exercise, wearing a too-tight bra, birth control pills, some foods, or nipple stimulation.

What Is the Treatment for High Levels of Prolactin in Blood?

  • To restore normal prolactin levels, the doctor will give thyroid replacement medication.

  • If medication is a cause, the doctor will work to find a treatment that can restore the levels to normal.

  • There is no need to seek treatment if the causative reason has not been identified.

  • A woman with hyperprolactinemia may continue to use birth control pills to avoid conception or regulate her periods. Women unable to produce estrogen due to high levels of prolactin should seek treatment.

  • If a prolactinoma (tumor in the pituitary gland) is obstructing eyesight, surgery may be required. Medicines like Bromocriptine and Cabergoline are used for treatment.


Prolactin is important for female breast physiology. Prolactin is involved in hundreds of physiologic functions, but two of the most important are milk production and the growth of mammary glands within breast tissues. Significant clinical pathologic processes are caused by a lack of prolactin secretion or excessive prolactin secretion. Prolactin hormone levels are essential for normal lactation.

Dr. Sunita Kothari
Dr. Sunita Kothari

Obstetrics and Gynecology


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