In women, a high blood level of prolactin often causes hypoestrogenism with anovulatory infertility and a decrease in menstruation. In some women, menstruation may disappear altogether (amenorrhoea). In others, menstruation may become irregular or menstrual flow may change. Women who are not pregnant or nursing may begin producing breast milk. Some women may experience a loss of libido (interest in sex) and breast pain, especially when prolactin levels begin to rise for the first time, as the hormone promotes tissue changes in the breast. Intercourse may become difficult or painful because of vaginal dryness.

In men, the most common symptoms of hyperprolactinaemia are decreased libido, sexual dysfunction (in both men and women), erectile dysfunction, infertility, and gynecomastia. Because men have no reliable indicator such as menstruation to signal a problem, many men with hyperprolactinaemia being caused by a pituitary adenoma may delay going to the doctor until they have headaches or eye problems caused by the enlarged pituitary pressing against the adjacent optic chiasm. They may not recognize a gradual loss of sexual function or libido. Only after treatment do some men realize they had a problem with sexual function.

Because of hypoestrogenism and hypoandrogenism, hyperprolactinaemia can lead to osteoporosis.

Galactorrhea hyperprolactinemia is increased blood prolactin levels associated with galactorrhea (abnormal milk secretion). It may be caused by such things as certain medications, pituitary disorders and thyroid disorders. The condition can occur in males as well as females. Relatively common etiologies include prolactinoma, medication effect, kidney failure, granulomatous diseases of the pituitary gland, and disorders which interfere with the hypothalamic inhibition of prolactin release. Ectopic (non-pituitary) production of prolactin may also occur. Galactorrhea hyperprolactinemia is listed as a “rare disease” by the Office of Rare Diseases of the National Institutes of Health. This means that it affects less than 200,000 people in the United States population.

Symptoms of galactorrhea hyperprolactinemia include a high blood prolactin level, abnormal milk production in the breast, galactorrhea, menstrual abnormalities, reduced libido, reduced fertility, puberty problems, and headaches.

Hyperprolactinaemia may be caused by either disinhibition (e.g., compression of the pituitary stalk or reduced dopamine levels) or excess production from a prolactinoma (a type of pituitary adenoma). A blood serum prolactin level of 1000–5000 mIU/L could be from either mechanism, but >5000 mIU/L (>200 µg/L) is likely due to the activity of an adenoma; macroadenomas (large tumours over 10 mm diameter) have levels of prolactin up to 100,000 mIU/L.

Hyperprolactinemia inhibits the secretion of gonadotropin-releasing hormone (GnRH) from the hypothalamus (by increasing the release of dopamine from the arcuate nucleus), which in turn inhibits the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the pituitary gland and results in diminished gonadal sex hormone production (termed hypogonadism). This is the cause of many of the symptoms described below.

In many people, elevated prolactin levels remain unexplained and may represent a form of hypothalamic–pituitary–adrenal axis dysregulation.

The symptoms due to a prolactinoma are broadly divided into those that are caused by increased prolactin levels or mass effect.

Those that are caused by increased prolactin levels are:

- Amenorrhea (disappearance of ovulation periods)

- Galactorrhea (Milk production; infrequent in men)

- Loss of axillary and pubic hair

- Hypogonadism (Reduced function of the gonads.)

- Gynecomastia (an increase in male breast size)

- Erectile dysfunction (in males)

Those that are caused by mass effect are:

- Bitemporal hemianopsia (due to pressure on the optic chiasm)

- Vertigo

- Nausea, vomiting

A prolactinoma is a benign tumor (adenoma) of the pituitary gland that produces a hormone called prolactin. It is the most common type of functioning pituitary tumor. Symptoms of prolactinoma are too much prolactin in the blood (hyperprolactinemia), or those caused by pressure of the tumor on surrounding tissues.

Prolactin stimulates the breast to produce milk, and has many other functions such as regulation of mood. Hence prolactin levels are usually higher during pregnancy and after childbirth. After delivery of a baby, a mother's prolactin levels come down to normal a few weeks after breastfeeding is discontinued. Each time the milk is dispensed, prolactin levels rise; this process may cycle to maintain milk production. In males it is responsible for the sexual refractory period after orgasm and excess levels can lead to erectile dysfunction.

Based on size, a prolactinoma can be classified as a "microprolactinoma" (10 mm diameter).

Galactorrhea can take place as a result of dysregulation of certain hormones. Hormonal causes most frequently associated with galactorrhea are hyperprolactinemia and thyroid conditions with elevated levels of thyroid-stimulating hormone (TSH) or thyrotropin-releasing hormone (TRH). No obvious cause is found in about 50% of cases.

Lactation requires the presence of prolactin, and the evaluation of galactorrhea includes eliciting a history for various medications or foods (methyldopa, opioids, antipsychotics, serotonin reuptake inhibitors, as well as licorice) and for behavioral causes (stress, and breast and chest wall stimulation), as well as evaluation for pregnancy, pituitary adenomas (with overproduction of prolactin or compression of the pituitary stalk), and hypothyroidism. Adenomas of the anterior pituitary are most often prolactinomas. Overproduction of prolactin leads to cessation of menstrual periods and infertility, which may be a diagnostic clue. Galactorrhea may also be caused by hormonal imbalances owing to birth control pills.

Galactorrhea is also a side effect associated with the use of the second-generation H receptor antagonist cimetidine (Tagamet). Galactorrhea can also be caused by antipsychotics that cause hyperprolactinemia by blocking dopamine receptors responsible for control of prolactin release. Of these, risperidone is the most notorious for causing this complication. Case reports suggest proton-pump inhibitors have been shown to cause galactorrhea.

When gigantomastia occurs in young women during puberty, the medical condition is known as "juvenile macromastia" or "juvenile gigantomastia" and sometimes as "virginal breast hypertrophy" or "virginal mammary hypertrophy". Along with the excessive breast size, other symptoms include red, itchy lesions and pain in the breasts. A diagnosis is made when an adolescent's breasts grow rapidly and achieve great weight usually soon after her first menstrual period. Some doctors suggest that the rapid breast development occurs before the onset of menstruation.

Some women with virginal breast hypertrophy experience breast growth at a steady rate for several years, after which the breasts rapidly develop exceeding normal growth. Some adolescent females experience minimal or negligible breast growth until their breasts suddenly grow very rapidly in a short period of time. This may cause considerable physical discomfort. Women suffering VBH often experience an excessive growth of their nipples as well. In severe cases of VBH, hypertrophy of the clitoris occurs.

At the onset of puberty, some females with who have experienced little or no breast development can reportedly reach three or more cup sizes within a few days (see below).

Galactorrhea (also spelled galactorrhoea) ( + ) or lactorrhea ( + ) is the spontaneous flow of milk from the breast, unassociated with childbirth or nursing.

Galactorrhea is reported to occur in 5–32% of women. Much of the difference in reported incidence can be attributed to different definitions of galactorrhea. Although frequently benign, it may be caused by serious underlying conditions and should be properly investigated. Galactorrhea also occurs in males, newborn infants and adolescents of both sexes.

The indication is a breast weight that exceeds approximately 3% of the total body weight. There are varying definitions of what is considered to be excessive breast tissue, that is the expected breast tissue plus extraordinary breast tissue, ranging from as little as up to with most physicians defining macromastia as excessive tissue of over . Some resources distinguish between macromastia (Greek, "macro": large, "mastos": breast), where excessive tissue is less than 2.5 kg, and gigantomastia (Greek, "gigantikos": giant), where excessive tissue is more than 2.5 kg. The enlargement can cause muscular discomfort and over-stretching of the skin envelope, which can lead in some cases to ulceration.

Hypertrophy of the breast can affect the breasts equally, but usually affects one breast more than the other, thereby causing asymmetry, when one breast is larger than the other. The condition can also individually affect the nipples and areola instead of or in addition to the entire breast. The effect can produce a minor size variation to an extremely large breast asymmetry. Breast hypertrophy is classified in one of five ways: as either pubertal (virginal hypertrophy), gestational (gravid macromastia), in adult women without any obvious cause, associated with penicillamine therapy, and associated with extreme obesity. Many definitions of macromastia and gigantomastia are based on the term of "excessive breast tissue", and are therefore somewhat arbitrary.

Common signs and symptoms of PCOS include the following:

- Menstrual disorders: PCOS mostly produces oligomenorrhea (fewer than nine menstrual periods in a year) or amenorrhea (no menstrual periods for three or more consecutive months), but other types of menstrual disorders may also occur.

- Infertility: This generally results directly from chronic anovulation (lack of ovulation).

- High levels of masculinizing hormones: Known as hyperandrogenism, the most common signs are acne and hirsutism (male pattern of hair growth, such as on the chin or chest), but it may produce hypermenorrhea (heavy and prolonged menstrual periods), androgenic alopecia (increased hair thinning or diffuse hair loss), or other symptoms. Approximately three-quarters of women with PCOS (by the diagnostic criteria of NIH/NICHD 1990) have evidence of hyperandrogenemia.

- Metabolic syndrome: This appears as a tendency towards central obesity and other symptoms associated with insulin resistance. Serum insulin, insulin resistance, and homocysteine levels are higher in women with PCOS.

Asians affected by PCOS are less likely to develop hirsutism than those of other ethnic backgrounds.

Secondary amenorrhea's most common and most easily diagnosable causes are pregnancy, thyroid disease, and hyperprolactinemia. A pregnancy test is a common first step for diagnosis. Hyperprolactinemia, characterized by high levels of the hormone prolactin, is often associated with a pituitary tumor. A dopamine agonist can often help relieve symptoms. The subsiding of the causal syndrome is usually enough to restore menses after a few months. Secondary amenorrhea may also be caused by outflow tract obstruction, often related to Asherman's Syndrome. Polycystic ovary syndrome can cause secondary amenorrhea, although the link between the two is not well understood. Ovarian failure related to early onset menopause can cause secondary amenorrhea, and although the condition can usually be treated, it is not always reversible. Secondary amenorrhea is also caused by stress, extreme weight loss, or excessive exercise. Young athletes are particularly vulnerable, although normal menses usually return with healthy body weight. Causes of secondary amenorrhea can also result in primary amenorrhea, especially if present before onset of menarche.

Hypoestrogenism, or estrogen deficiency, refers to a lower than normal level of estrogen, the primary sex hormone in women. In general, lower levels of estrogen may cause differences in the breasts, genitals, urinary tract, and skin.

Hypoestrogenism is most commonly found in women who are postmenopausal, have premature ovarian failure, or are suffering from amenorrhea; however, it is also associated with hyperprolactinemia and the use of gonadotropin-releasing hormone (GnRH) analogues in treatment of endometriosis. It has also been linked to scoliosis and young women with type 1 diabetes mellitus.

Presentations of low estrogen levels include hot flashes, headaches, lowered libido, and breast atrophy. Reduced bone density leading to secondary osteoporosis and atrophic changes such as pH change in the vagina is also linked to hypoestrogenism.

Low levels of estrogen can lead to dyspareunia and limited genital arousal because of changes in the four layers of the vaginal wall.

Hypoestrogenism is also considered one of the major risk factors for developing uncomplicated urinary tract infections (UTIs) in postmenopausal women who do not take hormone replacement therapy.

Polycystic ovary syndrome (PCOS) is a set of symptoms due to elevated androgens (male hormones) in women. Signs and symptoms of PCOS include irregular or no menstrual periods, heavy periods, excess body and facial hair, acne, pelvic pain, difficulty getting pregnant, and patches of thick, darker, velvety skin. Associated conditions include type 2 diabetes, obesity, obstructive sleep apnea, heart disease, mood disorders, and endometrial cancer.

PCOS is due to a combination of genetic and environmental factors. Risk factors include obesity, not enough physical exercise, and a family history of someone with the condition. Diagnosis is based on two of the following three findings: no ovulation, high androgen levels, and ovarian cysts. Cysts may be detectable by ultrasound. Other conditions that produce similar symptoms include adrenal hyperplasia, hypothyroidism, and hyperprolactinemia.

PCOS has no cure. Treatment may involve lifestyle changes such as weight loss and exercise. Birth control pills may help with improving the regularity of periods, excess hair growth, and acne. Metformin and anti-androgens may also help. Other typical acne treatments and hair removal techniques may be used. Efforts to improve fertility include weight loss, clomiphene, or metformin. In vitro fertilization is used by some in whom other measures are not effective.

PCOS is the most common endocrine disorder among women between the ages of 18 and 44. It affects approximately 2% to 20% of this age group depending on how it is defined. It is one of the leading causes of poor fertility. The earliest known description of what is now recognized as PCOS dates from 1721 in Italy.

Primary amenorrhoea can be diagnosed in female children by age 14 if no secondary sex characteristics, such as enlarged breasts and body hair, are present. In the absence of secondary sex characteristics, the most common cause of amenorrhoea is low levels of FSH and LH caused by a delay in puberty. Gonadal dysgenesis, often associated with Turner's Syndrome, or premature ovarian failure may also be to blame. If secondary sex characteristics are present, but menstruation is not, primary amenorrhoea can be diagnosed by age 16. A reason for this occurrence may be that a person phenotypically female but genetically male, a situation known as androgen insensitivity syndrome. If undescended testes are present, they are often removed after puberty (~21 years of age) due to the increased risk of testicular cancer. In the absence of undescended testes, an MRI can be used to determine whether or not a uterus is present. Müllerian agenesis causes around 15% of primary amenorrhoea cases. If a uterus is present, outflow track obstruction may be to blame for primary amenorrhoea.

For most women, alteration of menstrual periods is the principal indication of chronic anovulation. Ovulatory menstrual periods tend to be regular and predictable in terms of cycle length, duration and heaviness of bleeding, and other symptoms. Ovulatory periods are often accompanied by midcycle symptoms such as mittelschmerz or premenstrual symptoms. In contrast, anovulation usually manifests itself as irregularity of menstrual periods, that is, unpredictable variability of intervals, duration, or bleeding. Anovulation can also cause cessation of periods (secondary amenorrhea) or excessive bleeding (dysfunctional uterine bleeding). Mittelschmerz and premenstrual symptoms tend to be absent or reduced when a woman is anovulatory.

The principal feature of Laron syndrome is abnormally short stature (dwarfism). Physical symptoms include: prominent forehead, depressed nasal bridge, underdevelopment of mandible, truncal obesity, and micropenis in males. The breasts of females reach normal size, and in some are large in relation to body size. It has been suggested that hyperprolactinemia may contribute to the enlarged breast size. Seizures are frequently seen secondary to hypoglycemia. Some genetic variations decrease intellectual capacity. Laron syndrome patients also do not develop acne, except temporarily during treatment with IGF-1 (if performed).

In 2011, it was reported that people with this syndrome in the Ecuadorian villages are resistant to cancer and diabetes and are somewhat protected against aging. This is consistent with findings in mice with a defective growth hormone receptor gene.

Anovulation is usually associated with specific symptoms. However, it is important to note that they are not necessarily all displayed simultaneously. Amenorrhea (absence of menstruation) occurs in about 20% of women with ovulatory dysfunction. Infrequent and light menstruation occurs in about 40% of women with ovulatory dysfunction. Another potential symptom is irregular menstruation, where five or more menstrual cycles a year are five or more days shorter or longer than the length of the average cycle. Absence of mastodynia (breast pain or tenderness) occurs in about 20% of women with ovulatory problems. Also possible is increased body mass and facial hair, which is relatively easy to treat, and is often associated with PCOS, or polycystic ovary syndrome.

Laron's syndrome, or Laron-type dwarfism, is an autosomal recessive disorder characterized by an insensitivity to growth hormone (GH), usually caused by a mutant growth hormone receptor. It causes short stature and an increased sensitivity to insulin which means that they are less likely to develop diabetes mellitus type 2 and possibly cancer as well. It can be treated with injections of recombinant IGF-1.

Hypophysitis refers to an inflammation of the pituitary gland. Hypophysitis is rare and not fully understood.

Hypophysitis is commonly known as Lymphocytic Hypophysitis because the lymphocytic infiltration was limited to the anterior pituitary.

Hypophysitis is a fairly newly discovered disease. There are four categories of symptoms and signs. Most commonly, the initial symptoms are headaches and visual disturbances. Some symptoms are derived from the lesser functioning of the adenohypophyseal hormones. Of the adenohypophyseal hormones, the most frequently affected are corticotropes, lactotropes and gonadotropes, all which are found in the anterior pituitary. Polyuria is also a common symptom – which results in very dilute urine, as well as polydipsia which means having extreme thirst. Another symptom is hyperprolactinemia, which is when there are abnormally high prolactin levels in the blood. Usually, a mass will be found located on the sella turcica and loss of hormonal function.

Pickardt's syndrome may cause difficulties in differential diagnosis of pituitary adenomas, as both suprasellar hormone-inactive adenomas and prolactinomas may be associated with increased prolactin levels, central hypgogonadism and central hypothyroidism. Usually, the prolactin levels are higher in case of a true prolactinoma, but the concentration ranges overlap.

Pickardt syndrome (also Pickardt's syndrome or Pickardt–Fahlbusch syndrome) denotes a rare form of tertiary hypothyroidism that is caused by interruption of the portal veins connecting hypothalamus and pituitary.

It was characterized in 1972 and 1973.

Hyperprolactinemic SAHA syndrome is a cutaneous condition characterized by lateral hairiness, oligomenorrhea, and sometimes acne, seborrhea, FAGA I, and even galactorrhea.