Hyperprolactinemia occurs more commonly in women. The prevalence of hyperprolactinemia ranges from 0.4% in an unselected normal adult population (10,000 normal Japanese adults working at a single factory) to as high as 9 to 17% in women with reproductive disorders. Its prevalence was found to be 5% in a family planning clinic population, 9% in a population of women with adult-onset amenorrhea, and 17% among women with polycystic ovary syndrome.

Prolactin secretion in the pituitary is normally suppressed by the brain chemical dopamine. Drugs that block the effects of dopamine at the pituitary or deplete dopamine stores in the brain may cause the pituitary to secrete prolactin. These drugs include the major tranquillizers (phenothiazines), trifluoperazine (Stelazine), and haloperidol (Haldol); antipsychotic medications, such as risperidone and quetiapine; metoclopramide (Reglan), domperidone, cisapride used to treat gastro-oesophageal reflux; medication-induced nausea (such as cancer drugs); and, less often, alpha-methyldopa and reserpine, used to control hypertension; and estrogens and TRH. The sleep drug ramelteon (Rozerem) also increases the risk of hyperprolactinaemia. A benzodiazepine analog, etizolam, can also increase the risk of hyperprolactinaemia. In particular, the dopamine antagonists metoclopramide and domperidone are both powerful prolactin stimulators and have been used to stimulate breast milk secretion for decades. However, since prolactin is antagonized by dopamine and the body depends on the two being in balance, the risk of prolactin stimulation is generally present with all drugs that deplete dopamine, either directly or as a rebound effect.

The following are some of the possible medical causes of galactorrhea hyperprolactinemia that are listed by the Diseases Database: pregnancy, breastfeeding, sexual intercourse, shingles, prolactin secreting pituitary tumor, along with many others.

Physiological (i.e., non-pathological) causes include: pregnancy, breastfeeding, and mental stress.

A diagnosis of PCOS suggests an increased risk of the following:

- Endometrial hyperplasia and endometrial cancer (cancer of the uterine lining) are possible, due to overaccumulation of uterine lining, and also lack of progesterone resulting in prolonged stimulation of uterine cells by estrogen. It is not clear whether this risk is directly due to the syndrome or from the associated obesity, hyperinsulinemia, and hyperandrogenism.

- Insulin resistance/Type II diabetes. A review published in 2010 concluded that women with PCOS have an elevated prevalence of insulin resistance and type II diabetes, even when controlling for body mass index (BMI). PCOS also makes a woman, particularly if obese, prone to gestational diabetes.

- High blood pressure, in particular if obese or during pregnancy

- Depression and anxiety

- Dyslipidemia – disorders of lipid metabolism — cholesterol and triglycerides. Women with PCOS show a decreased removal of atherosclerosis-inducing remnants, seemingly independent of insulin resistance/Type II diabetes.

- Cardiovascular disease, with a meta-analysis estimating a 2-fold risk of arterial disease for women with PCOS relative to women without PCOS, independent of BMI.

- Strokes

- Weight gain

- Miscarriage

- Sleep apnea, particularly if obesity is present

- Non-alcoholic fatty liver disease, again particularly if obesity is present

- Acanthosis nigricans (patches of darkened skin under the arms, in the groin area, on the back of the neck)

- Autoimmune thyroiditis

Early diagnosis and treatment may reduce the risk of some of these, such as type 2 diabetes and heart disease.

The risk of ovarian cancer and breast cancer is not significantly increased overall.

Autopsy studies indicate that 6-25% of the U. S. population have small pituitary tumors. Forty percent of these pituitary tumors produce prolactin, but most are not considered clinically significant. Clinically significant pituitary tumors affect the health of approximately 14 out of 100,000 people. In non-selective surgical series, this tumor accounts for approximately 25-30% of all pituitary adenomas. Some growth hormone (GH)–producing tumors also co-secrete prolactin. Microprolactinomas are much more common than macroprolactinomas.

The prevalence of PCOS depends on the choice of diagnostic criteria. The World Health Organization estimates that it affects 116 million women worldwide as of 2010 (3.4% of women). One community-based prevalence study using the Rotterdam criteria found that about 18% of women had PCOS, and that 70% of them were previously undiagnosed.

Ultrasonographic findings of polycystic ovaries are found in 8–25% of normal women. 14% women on oral contraceptives are found to have polycystic ovaries. Ovarian cysts are also a common side effect of intrauterine devices (IUDs).

Hyperprolactinemia can cause reduced estrogen production in women and reduced testosterone production in men. Although estrogen/testosterone production may be restored after treatment for hyperprolactinemia, even a year or two without estrogen/testosterone can compromise bone strength, and patients should protect themselves from osteoporosis by increasing exercise and calcium intake through diet or supplementation, and by avoiding smoking. Patients may want to have bone density measurements to assess the effect of estrogen/testosterone deficiency on bone density. They may also want to discuss testosterone/estrogen replacement therapy with their physician.

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.

Neonatal milk or witch's milk is milk secreted from the breasts of approximately 5% of newborn infants. It is considered a normal variation and no treatment or testing is necessary. In folklore, witch's milk was believed to be a source of nourishment for witches' familiar spirits.

Breastfeeding is a common cause of secondary amenorrhoea, and often the condition lasts for over six months. Breastfeeding typically lasts longer than lactational amenorrhoea, and the duration of amenorrhoea varies depending on how often a women breastfeeds. Lactational amenorrhoea has been advocated as a method of family planning, especially in developing countries where access to other methods of contraception may be limited. Breastfeeding is said to prevent more births in the developing world than any other method of birth control or contraception. Lactational amenorrhoea is 98% percent effective as a method of preventing pregnancy in the first six months postpartum.

Untreated celiac disease can cause amenorrhea. Reproductive disorders may be the only manifestation of undiagnosed celiac disease and most cases are not recognized. For people with celiac, a gluten-free diet avoids or reduces the risk of developing reproductive disorders.

The underlying cause of the rapidly growing breast connective tissue, resulting in gigantic proportions, has not been well-elucidated. However, proposed factors have included increased levels/expression of or heightened sensitivity to certain hormones (e.g., estrogen, progesterone, and prolactin) and/or growth factors (e.g., hepatic growth factor, insulin-like growth factor 1, and epidermal growth factor) in the breasts. Macromastic breasts are reported to be composed mainly of adipose and fibrous tissue, while glandular tissue remains essentially stable.

Macromastia occurs in approximately half of women with aromatase excess syndrome (a condition of hyperestrogenism). Hyperprolactinemia has been reported as a cause of some cases of macromastia. Macromastia has also been associated with hypercalcemia (which is thought to be due to excessive production of parathyroid hormone-related protein) and, rarely, systemic lupus erythematosus and pseudoangiomatous stromal hyperplasia. It is also notable that approximately two-thirds of women with macromastia are obese. Aside from aromatase (as in aromatase excess syndrome), at least two other genetic mutations (one in PTEN) have been implicated in causing macromastia.

A handful of drugs have been associated with gigantomastia, including penicillamine, bucillamine, neothetazone, ciclosporin, and indinavir.

There are case reports of gigantomastia occurring in infants as well.

People with Laron syndrome have strikingly low rates of cancer and diabetes, although they appear to be at increased risk of accidental death due to their stature.

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.

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.

This accounts for around 10-15% of all cases of anovulation. The ovaries can stop working in about 5% of cases. This may be because the ovaries do not contain eggs. However, a complete blockage of the ovaries is rarely a cause of infertility. Blocked ovaries can start functioning again without a clear medical explanation. In some cases, the egg may have matured properly, but the follicle may have failed to burst (or the follicle may have burst without releasing the egg). This is called luteinised unruptured follicle syndrome (LUFS). Physical damage to the ovaries, or ovaries with multiple cysts, may affect their ability to function. This is called ovarian . Patients who are suffering from Stein-Leventhal syndrome (also referred to as polycystic ovary syndrome, or PCOS) can also suffer from anovulation. Up to 90% of cases of anovulation are caused by PCOS; this syndrome is usually hereditary.

Weight loss or anorexia can also cause hormonal imbalance, leading to irregular ovulation (dysovulation). It is possible that this mechanism evolved to protect the mother’s health. A pregnancy where the mother is weak could pose a risk to the baby’s and mother’s health. On the other hand, excess weight can also create ovarian dysfunctions. Dr Barbieri of Harvard Medical School has indicated that cases of anovulation are quite frequent in women with a BMI (body mass index) over 27 /. Unfortunately, not only does excess weight have a negative impact on ovulation itself, but also on treatment efficacy and outcomes of ART (assisted reproductive technique).

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.

Factors that can cause male as well as female infertility are:

- DNA damage

- DNA damage reduces fertility in female ovocytes, as caused by smoking, other xenobiotic DNA damaging agents (such as radiation or chemotherapy) or accumulation of the oxidative DNA damage 8-hydroxy-deoxyguanosine

- DNA damage reduces fertility in male sperm, as caused by oxidative DNA damage, smoking, other xenobiotic DNA damaging agents (such as drugs or chemotherapy) or other DNA damaging agents including reactive oxygen species, fever or high testicular temperature

- General factors

- Diabetes mellitus, thyroid disorders, undiagnosed and untreated coeliac disease, adrenal disease

- Hypothalamic-pituitary factors

- Hyperprolactinemia

- Hypopituitarism

- The presence of anti-thyroid antibodies is associated with an increased risk of unexplained subfertility with an odds ratio of 1.5 and 95% confidence interval of 1.1–2.0.

- Environmental factors

- Toxins such as glues, volatile organic solvents or silicones, physical agents, chemical dusts, and pesticides. Tobacco smokers are 60% more likely to be infertile than non-smokers.

German scientists have reported that a virus called Adeno-associated virus might have a role in male infertility, though it is otherwise not harmful. Other diseases such as chlamydia, and gonorrhea can also cause infertility, due to internal scarring (fallopian tube obstruction).

Molecular genetic investigations have shown that this disorder is mainly associated with mutations in the gene for the GH receptor. These can result in defective hormone binding to the ectodomain or reduced efficiency of dimerization of the receptor after hormone occupancy. There are exceptionally low levels of insulin-like growth factor (IGF-1) and its principal carrier protein, insulin-like growth factor binding protein 3.

A related condition involving postreceptor insensitivity to growth hormone has been associated with STAT5B.

Prevalence of infertility varies depending on the definition, i.e. on the time span involved in the failure to conceive.

- Infertility rates have increased by 4% since the 1980s, mostly from problems with fecundity due to an increase in age.

- Fertility problems affect one in seven couples in the UK. Most couples (about 84%) who have regular sexual intercourse (that is, every two to three days) and who do not use contraception get pregnant within a year. About 92 out of 100 couples who are trying to get pregnant do so within two years.

- Women become less fertile as they get older. For women aged 35, about 94% who have regular unprotected sexual intercourse get pregnant after three years of trying. For women aged 38, however, only about 77%. The effect of age upon men's fertility is less clear.

- In people going forward for IVF in the UK, roughly half of fertility problems with a diagnosed cause are due to problems with the man, and about half due to problems with the woman. However, about one in five cases of infertility has no clear diagnosed cause.

- In Britain, male factor infertility accounts for 25% of infertile couples, while 25% remain unexplained. 50% are female causes with 25% being due to anovulation and 25% tubal problems/other.

- In Sweden, approximately 10% of couples wanting children are infertile. In approximately one third of these cases the man is the factor, in one third the woman is the factor, and in the remaining third the infertility is a product of factors on both parts.

The prognosis for hypophysitis was variable for each individual. The depending factors for hypophysitis included the advancement of the mass on the Sella Turcica, percentage of fibrosis, and the body's response to corticosteroids. Through the use of Corticosteroids, the vision defects tend to recover when the gland size began to decrease. The prognoses of the limited number of reported cases were usually good.

Typical manifestations of Pickardt–Fahlbusch syndrome are hypothyroidism with reduced TSH values and functional hyperprolactinemia (which is caused by disinhibition of prolactin release). Other endocrine disorders that are usually associated with Pickardt syndrome are suprasellar failures like secondary hypogonadism, reduced levels of growth hormone and, in more severe cases, secondary adrenal insufficiency.

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.