Hormone secreting pituitary adenomas cause one of several forms of hyperpituitarism. The specifics depend on the type of hormone. Some tumors secrete more than one hormone, the most common combination being GH and prolactin, which present as unexpected bone growth and unexpected lactation (in both men and women).

A patient with pituitary adenoma may present with visual field defects, classically bitemporal hemianopsia. It arises from the compression of the optic nerve by the tumor. The specific area of the visual pathway at which compression by these tumours occurs is at the optic chiasma.

The anatomy of this structure causes pressure on it to produce a defect in the temporal visual field on both sides, a condition called bitemporal hemianopsia. If originating superior to the optic chiasm, more commonly in a craniopharyngioma of the pituitary stalk, the visual field defect will first appear as bitemporal inferior quadrantanopia, if originating inferior to the optic chiasm the visual field defect will first appear as bitemporal superior quadrantanopia. Lateral expansion of a pituitary adenoma can also compress the abducens nerve, causing a lateral rectus palsy.

Also, a pituitary adenoma can cause symptoms of increased intracranial pressure.

Prolactinomas often start to give symptoms especially during pregnancy, when the hormone progesterone increases the tumor's growth rate.

Various types of headaches are common in patients with pituitary adenomas. The adenoma may be the prime causative factor behind the headache or may serve to exacerbate a headache caused by other factors. Amongst the types of headaches experienced are both chronic and episodic migraine, and more uncommonly various unilateral headaches; primary stabbing headache, short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT) - another type of stabbing headache characterized by short stabs of pain -, cluster headache, and hemicrania continua (HS).

Non-secreting adenomas can go undetected for an extended time because no obvious abnormalities are seen; the gradual reduction in normal activities due to decreased production of hormones is rather less evident. For example, insufficient adrenocorticotropic hormone means that the adrenal glands will not produce sufficient cortisol, resulting in slow recovery from illness, inflammation and chronic fatigue; insufficient growth hormone in children and adolescents leads to diminished stature but which can have many other explanations.

Various psychiatric manifestations have been associated with pituitary disorders including pituitary adenomas. Psychiatric symptoms such as depression, anxiety apathy, emotional instability, easy irritability and hostility have been noted.

A adrenocortical adenoma (or adrenal cortical adenoma, or sometimes simply adrenal adenoma) is a benign tumor of the adrenal cortex.

It can present with Cushing's syndrome or primary aldosteronism. They may also secrete androgens, causing hyperandrogenism. Also, they are often diagnosed incidentally as incidentalomas.

Is a well circumscribed, yellow tumour in the adrenal cortex, which is usually 2–5 cm in diameter. The color of the tumour, as with adrenal cortex as a whole, is due to the stored lipid (mainly cholesterol), from which the cortical hormones are synthesized. These tumors are frequent incidental findings at post mortem examination, and appear to have produced no significant metabolic disorder; only a very small percentage lead to Cushing's syndrome. Nevertheless, these apparently non-functioning adenomas are most often encountered in elder obese people. There is some debate that they may really represent nodules in diffuse nodular cortical hyperplasia.

Very occasionally, a true adrenal cortical adenoma is associated with the clinical manifestations of Conn's syndrome, and can be shown to be excreting mineralocorticoids.

Almost all thyroid adenomas are follicular adenomas. Follicular adenomas can be described as "cold", "warm" or "hot" depending on their level of function. Histopathologically, follicular adenomas can be classified according to their cellular architecture and relative amounts of cellularity and colloid into the following types:

- Fetal (microfollicular) - these have the potential for microinvasion. These consist of small, closely packed follicles lined with epithelium.

- colloid (macrofollicular) - these do "not" have any potential for microinvasion

- embryonal (atypical) - have the potential for microinvasion.

- Hürthle cell adenoma (oxyphil or oncocytic tumor) - have the potential for microinvasion.

- Hyalinizing trabecular adenoma

Papillary adenomas are very rare.

A thyroid adenoma may be clinically silent ("cold" or "warm" adenoma), or it may be a functional tumor, producing excessive thyroid hormone ("hot" adenoma). In this case, it may result in symptomatic hyperthyroidism, and may be referred to as a toxic thyroid adenoma.

The first signs of a parathyroid adenoma and the resulting primary hyperparathyroidism can include bone fractures and urinary calculi such as kidney stones.

Oftentimes parathyroid adenoma is not diagnosed until found on standard blood-tests that reveal high calcium content in the blood, it can appear in urine tests as well. Patients may not be experiencing any noticeable symptoms but could be producing excessive amounts of calcium and eventually experience problems later in life if untreated. However, patients can experience common symptoms that can range from joint, muscle, and abdominal pain to slight discomfort. Additionally patients might be experiencing feelings of depression due to the hormonal imbalance. Constipation and exhaustion can also be experienced as a result of the irregularity in the bloodstream. There is also a potential that the kidneys could be damaged with the excess of calcium in the blood.

A parathyroid adenoma is a benign tumor of the parathyroid gland. It generally causes hyperparathyroidism; there are very few reports of parathyroid adenomas that were not associated with hyperparathyroidism.

A human being usually has four parathyroid glands located on the back surface of the thyroid in the neck. The parathyroids secrete parathyroid hormone (PTH), which increases the concentration of calcium in the blood by inducing the bones to release calcium into the blood and the kidneys to reabsorb it from the urine into the blood. When a parathyroid adenoma causes hyperparathyroidism, more parathyroid hormone is secreted, causing the calcium concentration of the blood to rise, resulting in hypercalcemia.

Hyperpituitarism is a condition due to the primary hypersecretion of pituitary hormones, it typically results from a pituitary adenoma. Children with hyperpituitarism is rare, disruption of growth regulation, either because of hormone hypersecretion or because of manifestations caused by local compression of the adenoma can occur.

Symptoms caused by hormone excess and associated mass effects include:

Patients with insulinomas usually develop neuroglycopenic symptoms. These include recurrent headache, lethargy, diplopia, and blurred vision, particularly with exercise or fasting. Severe hypoglycemia may result in seizures, coma, and permanent neurological damage. Symptoms resulting from the catecholaminergic response to hypoglycemia (i.e. tremulousness, palpitations, tachycardia, sweating, hunger, anxiety, nausea) are not as common. Sudden weight gain is sometimes seen.

Features that result from high level of GH or expanding tumor include:

- Soft tissue swelling visibly resulting in enlargement of the hands, feet, nose, lips and ears, and a general thickening of the skin

- Soft tissue swelling of internal organs, notably the heart with attendant weakening of its muscularity, and the kidneys, also the vocal cords resulting in a characteristic thick, deep voice and slowing of speech

- Generalized expansion of the skull at the fontanelle

- Pronounced brow protrusion, often with ocular distension (frontal bossing)

- Pronounced lower jaw protrusion (prognathism) with attendant macroglossia (enlargement of the tongue) and teeth spacing

- Hypertrichosis, hyperpigmentation and hyperhidrosis may occur in these patients.

- Acrochordon (skin tags)

- Carpal tunnel syndrome

An endocrine gland neoplasm is a neoplasm affecting one or more glands of the endocrine system.

Examples include:

- Adrenal tumor

- Pituitary adenoma

The most common form is thyroid cancer.

Condition such as pancreatic cancer or ovarian cancer can be considered endocrine tumors, or classified under other systems.

Pinealoma is often grouped with brain tumors because of its location.

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

An adenoma of a parathyroid gland may secrete inappropriately high amounts of parathyroid hormone and thereby cause primary hyperparathyroidism.

An insulinoma is a tumor of the pancreas that is derived from beta cells and secretes insulin. It is a rare form of a neuroendocrine tumor. Most insulinomas are benign in that they grow exclusively at their origin within the pancreas, but a minority metastasize. Insulinomas are one of the functional PanNET group ("functional" because it increases production of insulin; "PanNET" as an abbreviation of pancreatic neuroendocrine tumor). In the Medical Subject Headings classification, insulinoma is the only subtype of "islet cell adenoma".

Beta cells secrete insulin in response to increases in blood glucose. The resulting increase in insulin acts to lower blood glucose back to normal levels, at which point further secretion of insulin is stopped. In contrast, the secretion of insulin by insulinomas is not properly regulated by glucose, and the tumors continue to secrete insulin causing glucose levels to fall further than normal.

As a result, patients present symptoms of low blood glucose (hypoglycemia), which are improved by eating. The diagnosis of an insulinoma is usually made biochemically with low blood glucose, elevated insulin, proinsulin, and C-peptide levels, and confirmed by localizing the tumor with medical imaging or angiography. The definitive treatment is surgery.

Common signs and symptoms of Cushing's disease include the following:

- weight gain

- high blood pressure

- poor short-term memory

- irritability

- excess hair growth (women)

- Impaired immunological function

- red, ruddy face

- extra fat around neck

- moon face

- fatigue

- red stretch marks

- poor concentration

- irregular menstruation

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).

The initial symptoms of pituitary apoplexy are related to the increased pressure in and around the pituitary gland. The most common symptom, in over 95% of cases, is a sudden-onset headache located behind the eyes or around the temples. It is often associated with nausea and vomiting. Occasionally, the presence of blood leads to irritation of the lining of the brain, which may cause neck rigidity and intolerance to bright light, as well as a decreased level of consciousness. This occurs in 24% of cases.

Pressure on the part of the optic nerve known as the chiasm, which is located above the gland, leads to loss of vision on the outer side of the visual field on both sides, as this corresponds to areas on the retinas supplied by these parts of the optic nerve; it is encountered in 75% of cases. Visual acuity is reduced in half, and over 60% have a visual field defect. The visual loss depends on which part of the nerve is affected. If the part of the nerve between the eye and the chiasm is compressed, the result is vision loss in one eye. If the part after the chiasm is affected, visual loss on one side of the visual field occurs.

Adjacent to the pituitary lies a part of the skull base known as the cavernous sinus. This contains a number of nerves that control the eye muscles. 70% of people with pituitary apoplexy experience double vision due to compression of one of the nerves. In half of these cases, the oculomotor nerve (the third cranial nerve), which controls a number of eye muscles, is affected. This leads to diagonal double vision and a dilated pupil. The fourth (trochlear) and sixth (abducens) cranial nerves are located in the same compartment and can cause diagonal or horizontal double vision, respectively. The oculomotor nerve is predominantly affected as it lies closest to the pituitary. The cavernous sinus also contains the carotid artery, which supplies blood to the brain; occasionally, compression of the artery can lead to one-sided weakness and other symptoms of stroke.

The less-common signs and symptoms of Cushing's disease include the following:

- insomnia

- recurrent infection

- thin skin and stretch marks

- easy bruising

- weak bones

- acne

- balding (women)

- depression

- hip and shoulder weakness

- swelling of feet/legs

- diabetes mellitus

- erectile dysfunction

Pituitary adenomas are seen in 10% of neurological patients. A lot of them remain undiagnosed. Treatment is usually surgical, to which patients generally respond well. The most common subtype, prolactinoma, is seen more often in women, and is frequently diagnosed during pregnancy as the hormone progesterone increases its growth. Medical therapy with cabergoline or bromocriptine generally suppresses prolactinomas; progesterone antagonist therapy has not proven to be successful.

The pituitary gland consists of two parts, the anterior (front) and posterior (back) pituitary. Both parts release hormones that control numerous other organs. In pituitary apoplexy, the main initial problem is a lack of secretion of adrenocorticotropic hormone (ACTH, corticotropin), which stimulates the secretion of cortisol by the adrenal gland. This occurs in 70% of those with pituitary apoplexy. A sudden lack of cortisol in the body leads to a constellation of symptoms called "adrenal crisis" or "Addisonian crisis" (after a complication of Addison's disease, the main cause of adrenal dysfunction and low cortisol levels). The main problems are low blood pressure (particularly on standing), low blood sugars (which can lead to coma) and abdominal pain; the low blood pressure can be life-threatening and requires immediate medical attention.

Hyponatremia, an unusually low level of sodium in the blood that may cause confusion and seizures, is found in 40% of cases. This may be caused by low cortisol levels or by inappropriate release of antidiuretic hormone (ADH) from the posterior pituitary. Several other hormonal deficiencies may develop in the subacute phase. 50% have a deficiency in thyroid-stimulating hormone (TSH), leading to undersecretion of thyroid hormone by the thyroid gland and characteristic symptoms such as fatigue, weight gain, and cold intolerance. 75% develop a deficiency to gonadotropins (LH and FSH), which control the reproductive hormone glands. This leads to a disrupted menstrual cycle, infertility and decreased libido.

Deficiency of all anterior pituitary hormones is more common than individual hormone deficiency.

Deficiency of luteinizing hormone (LH) and follicle-stimulating hormone (FSH), together referred to as the gonadotropins, leads to different symptoms in men and women. Women experience oligo- or amenorrhea (infrequent/light or absent menstrual periods respectively) and infertility. Men lose facial, scrotal and trunk hair, as well as suffering decreased muscle mass and anemia. Both sexes may experience a decrease in libido and loss of sexual function, and have an increased risk of osteoporosis (bone fragility). Lack of LH/FSH in children is associated with delayed puberty.

Growth hormone (GH) deficiency leads to a decrease in muscle mass, central obesity (increase in body fat around the waist) and impaired attention and memory. Children experience growth retardation and short stature.

Adrenocorticotropic hormone (ACTH) deficiency leads to adrenal insufficiency, a lack of production of glucocorticoids such as cortisol by the adrenal gland. If the problem is chronic, symptoms consist of fatigue, weight loss, failure to thrive (in children), delayed puberty (in adolescents), hypoglycemia (low blood sugar levels), anemia and hyponatremia (low sodium levels). If the onset is abrupt, collapse, shock and vomiting may occur. ACTH deficiency is highly similar to primary Addison's disease, which is cortisol deficiency as the result of direct damage to the adrenal glands; the latter form, however, often leads to hyperpigmentation of the skin, which does not occur in ACTH deficiency.

Thyroid-stimulating hormone (TSH) deficiency leads to hypothyroidism (lack of production of thyroxine (T4) and triiodothyronine (T3) in the thyroid). Typical symptoms are tiredness, intolerance to cold, constipation, weight gain, hair loss and slowed thinking, as well as a slowed heart rate and low blood pressure. In children, hypothyroidism leads to delayed growth and in extreme inborn forms to a syndrome called "cretinism".

Prolactin (PRL) plays a role in breastfeeding, and inability to breastfeed may point at abnormally low prolactin levels.

The hormones of the pituitary have different actions in the body, and the symptoms of hypopituitarism therefore depend on which hormone is deficient. The symptoms may be subtle and are often initially attributed to other causes. In most of the cases, three or more hormones are deficient. The most common problem is insufficiency of follicle-stimulating hormone (FSH) and/or luteinizing hormone (LH) leading to sex hormone abnormalities. Growth hormone deficiency is more common in people with an underlying tumor than those with other causes.

Sometimes, there are additional symptoms that arise from the underlying cause; for instance, if the hypopituitarism is due to a growth hormone-producing tumor, there may be symptoms of acromegaly (enlargement of the hands and feet, coarse facial features), and if the tumor extends to the optic nerve or optic chiasm, there may be visual field defects. Headaches may also accompany pituitary tumors, as well as pituitary apoplexy (infarction or haemorrhage of a pituitary tumor) and lymphocytic hypophysitis (autoimmune inflammation of the pituitary). Apoplexy, in addition to sudden headaches and rapidly worsening visual loss, may also be associated with double vision that results from compression of the nerves in the adjacent cavernous sinus that control the eye muscles.

Pituitary failure results in many changes in the skin, hair and nails as a result of the absence of pituitary hormone action on these sites.

A pituitary disease is a disorder primarily affecting the pituitary gland.

The main disorders involving the pituitary gland are:

Overproduction or underproduction of a pituitary hormone will affect the respective end-organ. For example, insufficient production (hyposecretion) of thyroid stimulating hormone (TSH) in the pituitary gland will cause hypothyroidism, while overproduction (hypersecretion) of TSH will cause hyperthyroidism. Thyroidisms caused by the pituitary gland are less common though, accounting for less than 10% of all hypothyroidism cases and much less than 1% of hyperthyroidism cases.

The syndrome can present with variable symptoms, even between members of the same family harboring the same mutation. Typically most or all tissues are resistant to thyroid hormone, so despite raised measures of serum thyroid hormone the individual may appear euthyroid (have no symptoms of over- or underactivity of the thyroid gland). The most common symptoms are goiter and tachycardia. It has also been linked to some cases of attention deficit hyperactivity disorder (ADHD), although the majority of people with that diagnosis have no thyroid problems.

An association with depression has been proposed.