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What are pituitary disorders?
Pituitary disorders are conditions caused by too much or too little of one or more of the hormones produced by the pituitary gland. A pituitary tumor compressing surrounding tissues can also cause symptoms of a pituitary disorder.
The pituitary gland is part of the endocrine system, a very complex network that consists of various glands located throughout the body. The glands produce hormones that affect processes throughout the body.
The pituitary is a pea-sized gland in the center of the head behind the sinus cavity, at the bottom of the brain, below the hypothalamus. The hypothalamus communicates with other parts of the brain and nervous system to regulate the body. It sends hormones that signal the pituitary to start or stop producing hormones. Hormones produced by the pituitary travel to other glands throughout the body and stimulate them to produce different hormones.
The pituitary has two parts: the anterior (front) and the posterior (back), which produce different hormones:
The anterior pituitary produces:
- Growth hormone (GH)
- Adrenocorticotrophic hormone (ACTH)
- Thyroid-stimulating hormone (TSH)
- Luteinizing hormone (LH)
- Follicle-stimulating hormone (FSH)
These hormones help regulate bone growth, muscle mass, the body’s response to stress, blood sugar, the rate at which the body uses energy (metabolic rate), the development of secondary sexual characteristics, and fertility, They affect specific “target” tissues throughout the body, including the thyroid gland, adrenal glands, ovaries (women), and testicles (men).
The posterior pituitary stores oxytocin and antidiuretic hormone (ADH), which are produced in the hypothalamus.
- ADH controls the amount of water that the kidneys release, which in turn helps regulate the balance of water in the body.
- Oxytocin stimulates the contraction of the uterus during and after childbirth and is responsible for stimulating the release of milk during breastfeeding.
Pituitary disorders causing the production of too much or too little pituitary hormone can produce a variety of symptoms depending on which hormones and target tissues are affected.
About Pituitary Disorders
The growth of a tumor is the most common problem with the pituitary. While most are benign (pituitary adenoma), they can produce excessive amounts of a specific pituitary hormone, reduce the production of other hormones, and compress surrounding tissues. Blood vessels and the optic nerves are in close proximity to the pituitary gland. Pressure from a tumor can cause headaches, vision problems (including loss of vision), fatigue, weakness, and seizures, as well as a host of signs and symptoms related to decreased hormone production.
Other causes of pituitary disorders include:
- Inherited genetic mutations
- Congenital conditions (present at birth)
- Head trauma
- Low or lack of blood supply to the pituitary
- Surgical or radiation treatment of a previous pituitary disorder
- A malignant tumor (rare)
- An unknown condition or due to causes that are not yet well understood
- Iron overload; hemochromatosis/frequent blood transfusions
Examples of Disorders
Examples of Common Pituitary Disorders
- Pituitary tumors: may or may not produce and release hormone; most are benign; may cause visual disturbances and headaches as they grow and compress surrounding tissues; they often result in excessive amounts of one pituitary hormone and decreases in others.
- Growth hormone deficiency: in children, it causes delayed growth and short height; in adults, it can lead to muscular weakness, fatigue, decreased bone mass, and obesity.
- Hypopituitarism: causes may include tumors, trauma, decreased pituitary blood supply, infection, sarcoidosis, an autoimmune process, radiation, surgical removal of the pituitary, or a side effect of pituitary surgery; it results in a general decrease in pituitary hormone production.
- Hyperprolactinemia: caused by a pituitary tumor that secretes prolactin or a tumor that prevents the regulation of prolactin production; can cause production of breast milk outside of pregnancy (galactorrhea) and a lack of monthly menstrual periods (amenorrhea) in women and, in men, decreased sex drive and erectile dysfunction.
- Empty Sella Syndrome: the sella is a hollow area in the bone of the skull that holds the pituitary; a membrane, called the sellae, sits on top of the pituitary and protects it within this socket. If there is an opening in this membrane, spinal fluid may press on the pituitary, flattening it and making it appear as though the sella is empty when viewed with an imaging procedure (i.e, MRI). Sometimes, people can have empty sella syndrome caused by other factors, such as a tumor or radiation therapy.
- Craniopharyngioma: most commonly occurs in children and teens but also occurs in adults over 50 years old; while benign, it but may put pressure on the pituitary, causing hypopituitarism, headaches, vision problems, and delayed growth.
Examples of Rare Pituitary Disorders
- Acromegaly and Gigantism: excess growth hormone production, usually due to a benign tumor (adenoma); when it occurs in childhood, it causes gigantism associated with excessive bone growth and abnormally tall stature; in adults, it causes acromegaly, with increases in bone thickness, coarsened facial features, enlarged hands and feet, carpal tunnel syndrome, headaches, sweating, sleep apnea, fatigue, and hypertension along with an increased risk of diabetes mellitus and colon cancer.
- Adrenal insufficiency: a rare condition that may be caused by pituitary dysfunction. A decrease in the production of the pituitary hormone adrenocorticotropic hormone (ACTH) is at the root of secondary adrenal insufficiency. ACTH is a pituitary messenger; it tells the adrenal cortex to produce cortisol. If there is insufficient ACTH, due to pituitary damage, a pituitary tumor, or some other cause, then cortisol production is not stimulated. Symptoms are related to low levels of cortisone and aldosterone, hormones that regulate metabolism and blood pressure along with other vital functions.
- Cushing Disease: signs and symptoms related to Cushing syndrome caused by a pituitary tumor that produces excess ACTH. Too much ACTH stimulates the adrenal glands to produce excess amounts of the hormone cortisol; symptoms vary but include, for example, obesity in the torso with thinner arms and legs, a large, rounded face, thin skin, pink streaks on the abdomen, muscular weakness, osteoporosis, high blood sugar, and high blood pressure.
- Diabetes Insipidus: decreased production of ADH by the hypothalamus; an individual’s kidneys don’t conserve water and concentrate urine and the person becomes thirsty and has frequent, dilute urination.
- Nelson Syndrome: may result when both adrenal glands are removed as part of the treatment for Cushing disease; a pituitary tumor that produces ACTH enlarges and can cause loss of other pituitary hormones; it can also cause darkening of the skin due to increased production of melanocyte-stimulating hormone (MSH).
- Multiple Endocrine Neoplasia Type 1 (MEN1): an inherited genetic mutation that increases the risk of developing tumors in the pituitary and in other endocrine glands.
- Kallman Syndrome: an inherited condition caused by deficient release of gonadotropin-releasing hormone (GnRH); it leads to lack of FSH and LH production, causes delayed or absent puberty, and is associated with no sense of smell.
- Pituitary infarction: the most common cause is bleeding due to a noncancerous pituitary tumor; it may cause gland tissue damage and lead to hypopituitarism.
- Sheehan Syndrome: a very rare condition caused by severe bleeding during childbirth that can cause the pituitary gland to lose function; it is a specific kind of pituitary infarction.
Laboratory testing may be used to detect excess or deficient hormones, help diagnose a pituitary disorder, determine the severity, and may be ordered at intervals to monitor the effectiveness of treatment over time. Some individuals may have inherited conditions and thus a lifetime risk of developing a pituitary disorder, so long-term monitoring may be necessary in some cases.
Testing frequently includes measurements of both the hormones that the pituitary produces, such as thyroid-stimulating hormone (TSH), and the hormones of other endocrine glands that the pituitary stimulates, such as the thyroid gland hormone T4 (thyroxine).
Examples of hormones that may be tested in the evaluation of pituitary disorders include:
Pituitary hormones are released as needed so levels in the blood may:
- Be relatively constant (e.g., TSH)
- Vary over the course of a day (e.g., cortisol)
- Vary over a cycle (e.g., FSH and LH during the menstrual cycle)
- Be increased in specific situations, such as prolactin in women who are breastfeeding or ACTH as a response to stress
Because of these variations in when hormones are released, detecting excess and deficient hormones often requires tests that measure hormonal changes after a person takes medications to suppress or stimulate the production of hormones (i.e., suppression or stimulation tests).
A water deprivation test, which involves measuring urine and serum osmolality, may be used to help diagnose diabetes insipidus.
Imaging tests may be used to evaluate glands and detect tumors. These may include:
- MRI (magnetic resonance imaging)
- CT (computed tomography)
For more on these, visit RadiologyInfo.org.
Treatment depends on the cause of the pituitary disorder.
- When a pituitary tumor is present, surgery may be performed to remove the tumor. The pituitary gland is accessed through the nose in a procedure called transsphenoidal surgery. The procedure is delicate and requires a surgeon who is experienced in the procedure.
- Medications may be used to block hormone action, to shrink pituitary tumors to reduce compression symptoms. They may sometimes be used prior to surgery.
- Hormone replacement may be used to supplement missing or deficient hormones.
- Targeted radiation therapy may be used in conjunction with other treatments to decrease tumor size and excess hormone production.
Treatment may not completely resolve a condition or may cause additional pituitary dysfunction, either immediately or in the future (such as with surgery and radiation, respectively). Individuals should work with their healthcare practitioner and/or an endocrinologist, a doctor who specializes in treating disorders of the endocrine system, to determine the best course of treatment for them.
Sources Used in Current Review
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