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Pituitary Disorders: Conditions
Pituitary tumors (also called pituitary adenomas) can result in hormonal overproduction causing serious endocrine disturbances such as acromegaly (excess GH), Cushing's disease (excess ACTH) or prolactinoma (excess prolactin). Other pituitary adenomas are non-functional or "endocrine-inactive," meaning that they do not produce excess hormones. Instead, as these tumors enlarge, they can cause compression of the normal pituitary gland leading to decreased or absent hormone production (hypopituitarism or pituitary failure), visual loss from optic chiasm or optic nerve compression and headaches. Pituitary failure may also result from bleeding into a pituitary tumor, pituitary or intracranial surgery, radiation therapy to the pituitary or head trauma. Other tumors that arise near the pituitary gland which can also impact pituitary hormonal function include Rathke's cleft cysts, craniopharyngiomas, meningiomas, chordomas, gliomas and epidermoid cysts.
Pituitary tumors are the most common cause of pituitary disorders. They are also called pituitary adenomas since 99% of them are benign. Most pituitary adenomas do not produce excessive amount of hormones (non-functional adenomas). Other pituitary tumors can result in hormonal overproduction causing serious endocrine disturbances such as acromegaly (GH excess), Cushing's disease (ACTH excess) or prolactinoma (prolactin excess). Small pituitary adenomas (less than 1 cm in diameter or smaller than a grape) are called microadenomas, while larger tumors are called macroadenomas. As pituitary tumors enlarge, they can cause compression of the normal pituitary gland and decreased hormone production (pituitary insufficiency or hypopituitarism), optic chiasm/ nerve compression causing visual problems and headaches.
Non-functional Pituitary Tumors
Small non-functional pituitary adenomas (2-3 mm in size) occur in about 10% of population and are usually detected during brain imaging done for a different reason (pituitary incidentalomas,). These small tumors usually do not cause any problems; however they can sometimes grow and cause problems, so clinical supervision is necessary. With larger non-functional tumors, patients develop symptoms of mass effects, including headaches, visual problems, and symptoms of pituitary insufficiency. Visual problems are serious complications of pituitary tumors that usually begin with decrease in the peripheral vision. Untreated, visual problems typically progress to blindness. Conversely, visual problems in incipient stages may improve after surgical treatment of pituitary tumors.
Recent progress in our ability to characterize and diagnose these tumors will be discussed here.
Functioning Pituitary Tumors
Pituitary tumors causing hormonal excess are presented below.
Acromegaly is caused by pituitary tumor that produces excess growth hormone (GH). It most commonly affects middle-aged adults and can result in serious illness and premature death. If the disease develops before a person has stopped growing, it causes gigantism since two much GH promotes growth of bones in the body. The most common findings of GH excess are the enlargement of the hands, feet and face and excessive sweating. Patients may also present with headaches, irregular periods (in women), impotence (in men) and peripheral vision loss. Patients may also have an enlarged heart, tingling or pain in extremities (peripheral neuropathy), and excessive sleepiness during the day (sleep apnea). Because of its slow and often insidious onset, it frequently takes a long time until acromegaly is finally diagnosed. Once recognized, acromegaly is treatable in most patients. The primary treatment is usually surgery followed by radiotherapy or medications that decrease the manifestations of GH excess.
Cushing's diasease refers to the pituitary adenoma that produces excess ACTH which in turn stimulates the cortisol secretion by the adrenal glands located above each kidney. Patients with Cushing's disease present with progressive weight gain, muscle weakness, easy skin bruising, impotence (in men), irregular periods (in women), and depression. Patients may also have high blood pressure, diabetes mellitus, and osteoporosis. Many of these problems are non-specific, meaning that people who have them usually do not have Cushing's syndrome. On the other hand, most patients who have Cushing's syndrome have some, but not all, of these features. There is a characteristic appearance in many patients with Cushing's disease which includes a round face, excess fat pad in the back of the neck ("buffalo hump"), excess fat in the collarbone area, weight gain primarily in the abdominal region, with relative thinning of the arms and legs, and red abdominal stretch marks. Diagnosis of Cushing's disease is sometimes challenging and has to be done by an experienced Endocrinologist. The treatment is usually pituitary surgery, which needs to be done by an experienced neurosurgeon. Radiotherapy may be used in some patients that are not cured by surgery. Medical therapy has only a limited role in the management of Cushing's disease. In the majority of cases, surgical curative treatment of Cushing's disease leads to improvement of most of the features mentioned.
Prolactinomas are benign tumors of the pituitary gland that produce excessive amount of a hormone called prolactin. Symptoms of prolactinoma are caused by too high prolactin in the blood (hyperprolactinemia) or by pressure of the tumor on surrounding tissues (if the tumor is large). Hyperprolactinemia causes milk discharge from the breast (galactorrhea), menstrual irregularities (oligomenorrhea or amenorrhea) and infertility in women and impotence in men. Prolactinomas are usually successfully treated with medications that shrink the tumor, even if large. Only a minority of prolactinomas require surgery.
Hyperprolactinemia does not mean that the patient has a pituitary tumor, since it can occur in patients taking certain medications of having other medical conditions. Evaluation by an Endocrinologist is necessary in order to differentiate these conditions.
The pituitary gland produces a number of hormones, which are released into the blood to control other glands in the body (thyroid, adrenal, ovary or testicles). If the pituitary is not producing one or more of these hormones, the condition is called hypopituitarism. If all the hormones produced by the anterior pituitary are decreased, the condition is called panhypopituitarism.
Hypopituitarism is most often caused by large benign tumors of the pituitary gland, or of the brain in the region of the hypothalamus. Pituitary underactivity may be caused by the direct pressure of the tumor mass on the normal pituitary or by the effects of surgery or radiotherapy used to treat the pituitary tumors. Less frequently, hypopituitarism can be caused by infections (such as meningitis) in or around the brain or by severe blood loss, by head injury, or by other rare diseases.
Some of the clinical features that may be associated with hypopituitarism include excessive tiredness and decreased energy, irregular periods (oligomenorrhea) or loss of normal menstrual function (amenorrhea), impotence (in men), infertility, increased sensitivity to cold, constipation, dry skin, low blood pressure and lightheadedness upon standing (postural hypotension).
Treatment of hypopituitarism consists of long-term replacement therapy (table 1), since pituitary hormone deficits are rarely reversed after tumor removal.
Table 1. Overview of the pituitary hormone deficiencies
| Children: Growth delay
Adults: Decreased muscle mass, increased body fat, elevated cholesterol, low bone density (osteoporosis), impaired psychological well-being, poor quality of life
|Recombinant Human Growth Hormone- Given once daily as an injection under the skin
|LH / FSH
| Decreased libido, erectile dysfunction, irregular or absent menses, decreased body hair, decreased muscle strength, hot flashes, mood changes
Men: Testosterone- Given as either topical gel or patch or injections
Women: Estrogen + Progesterone-Given as either topical patch or pills
| Poor appetite, nausea, weakness, vomiting, low blood sugar, low blood pressure, dizziness, body aches
||Hydrocortisone or Prednisone-Given as daily pills
| Fatigue, weakness, cold intolerance, dry skin, constipation, heavy/painful menses, weight gain, memory loss, mood disturbance
|| Levothyroxine - Given as daily pills (some examples include Synthroid or Levoxyl or Levothroid or Armour Thyroid)
|| Inability to lactate
|| No treatment available
| Increased thirst and frequent urination
|| DDAVP- Given either as daily pills or nasal spray
Other pituitary diseases
Although pituitary tumors are the most frequent pituitary lesions, other conditions can also result in pituitary problems.
Tumors in the pituitary region other than pituitary adenomas
Craniopharingiomas, cysts and meningiomas are examples of tumors that originate in the proximity of the pituitary gland and may cause hypopituitarism, headaches, visual and neurological problems. Many times these tumors are large and difficult to remove completely. Irradiation is often necessary for craniopharingiomas and meningiomas postoperatively.
Non-tumoral pituitary diseases
Empty sella syndrome occurs when cerebrospinal fluid is found in the sellar space that is normally occupied by the pituitary gland. This condition can occur spontaneously or after treatment of a pituitary tumor with surgery, medications or radioation. Empty sella sometimes associate hypopituitarism and requires hormonal replacement.
Medical diseases like sarcoidosis, histiocytosis and hemochromatosis can cause infiltration of the pituitary gland causing pituitary hormone imbalances.
Rarely infections or autoimmune conditions affect the pituitary gland causing hypophysitis, also characterized by hormonal abnormalities.
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The information contained in these pages is intended to be used solely for the information of the reader. It is neither intended nor implied to be a substitute for professional medical advice. Techniques, procedures, drugs, or other diagnostic or therapeutic items mentioned should be thoroughly researched and adequate training obtained before their use is contemplated. Non-physicians reading these pages are encouraged to discuss any questions they may have with their own physician.
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