Pituitary Disorders


 

Pituitary infarction

Definition
Pituitary infarction is the death of an area of tissue in the pituitary gland, a small gland joined to the hypothalamus (part of the brain). The pituitary produces many of the hormones that control essential body processes.

Alternative Names
Pituitary apoplexy

Causes
Pituitary infarction is most commonly caused by bleeding into a benign tumor of the pituitary, which kills an area of tissue in the pituitary gland. When this bleeding occurs in a woman during or immediately after childbirth, it is called Sheehan's syndrome.

Risk factors for pituitary infarction include diabetes, bleeding disorders, head trauma, pituitary radiation, and use of a breathing machine. However, in most cases, the cause is not clear.

Pituitary infarction is usually acute (short period of symptoms) and can be life-threatening.

Symptoms
Symptoms are usually acute and include severe headache, ophthalmoplegia (paralysis of the eye muscles causing double vision), and symptoms of acute adrenal insufficiency (low blood pressure, nausea, and vomiting).

Less commonly, pituitary dysfunction may appear more slowly. In Sheehan's syndrome, for example, the initial symptom may be a failure to produce milk caused by a lack of the hormone prolactin.

Over time, insufficiency in other pituitary hormones may develop, causing symptoms of the following conditions:

  • Hypogonadism
    • Amenorrhea in women
    • Sexual dysfunction and loss of muscle mass in men
  • Hypothyroidism
    • Dry skin
    • Mental slowing
    • Weight gain
    • Cold intolerance
    • Hoarseness
  • Hypoadrenalism (if not already present or treated)
    • Low blood pressure
    • Nausea
    • Inability to deal with physical stress
  • Growth hormone deficiency
    • Fatigue
    • Lack of energy
    • Loss of bone and muscle
    • Increased abdominal fat
    • Dyslipidemia (problems with fat metabolism)

When the posterior pituitary is involved (rare), there may be uncontrolled urination.

Exams and Tests
Signs of acute infarction may include ophthalmoplegia, visual field defects, and hypotension (low blood pressure).

Signs of chronic pituitary insufficiency include:

  • Hypogonadism
    • Sparse axillary and pubic hair
    • Loss of sexual function
    • Cessation of mentrual cycle in women
    • Erectile dyfunction in men
  • Hypothyroidism
    • Dry hair and skin
    • Puffy face
    • Delayed reflexes
  • Hypoadrenalism
    • Hypotension
    • Poor response to stress and infection
  • Hypoprolactinemia -- lack of lactation
  • Growth hormone deficiency -- loss of muscle mass
  • General -- fine, pale, wrinkled skin

Tests may include:

  • Test for abnormal visual fields
  • MRI or CT scan showing hemorrhage
  • Low estradiol/testosterone with low FSH and LH
  • Low free T4 and TSH
  • Low cortisol and ACTH -- rise of cortisol may be absent with Cortrosyn stimulation
  • Low GH and somatomedin C (IGF-1)
  • Low prolactin
  • Elevated LDL cholesterol
  • Low bone density

Treatment
Treatment for acute infarction may require surgery to decompress the area of the pituitary and improve visual symptoms. Severe cases constitute a surgical emergency. Immediate treatment with adrenal replacement hormones (glucocorticoids) is essential.

Replacement of other missing hormones is also required, including sex hormones (estrogen/testosterone) and thyroid hormone. Evidence is growing for the need for growth hormone replacement.

Outlook (Prognosis)
Acute pituitary infarction is a potentially life-threatening event. Prognosis for chronic deficiency (which is detected and treated) is good.

Possible Complications
Complications of untreated pituitary infarction can include visual loss and adrenal crisis. If other deficient hormones are not replaced, problems related to hypothyroidism and hypogonadism may develop.

When to Contact a Medical Professional
Call your health care provider if you have any signs or symptoms of chronic pituitary insufficiency.

Go to the emergency room or call the local emergency number (such as 911) if you have symptoms of acute pituitary infarction, including headache, eye weakness, low blood pressure (which can cause fainting), nausea, and vomiting.

Patients with a diagnosed pituitary tumor should have a heightened level of suspicion if these symptoms arise.

 

Pituitary Cushing’s (Cushing’s disease)

Definition
Pituitary Cushing's is a condition in which the pituitary gland (an organ of the endocrine system) secretes excess adrenocorticotropic hormone (ACTH).

Causes
Cushing's disease is a form of Cushing's syndrome, in which excess cortisol (a stress hormone) is secreted. In the case of Cushing's disease, the problem is caused by a tumor or hyperplasia (excess growth) of the pituitary gland. The pituitary gland is located in the base of the skull and regulates the activities of many glands and body processes.

When ACTH is secreted by the pituitary gland, the adrenal glands release cortisol. In Cushing's disease, there is too much ACTH, which leads to an excess release of cortisol. This hormone, normally released during stressful situations, controls the body's use of carbohydrates, fats, and proteins and also plays a role in suppressing the body's response to inflammation.

Symptoms

  • Moon face (round, red, and full)
  • Buffalo hump (a collection of fat on the back of the neck)
  • Central obesity with protruding abdomen and thin extremities
  • Weight gain
  • Weakness
  • Backache
  • Headache
  • Acne or superficial skin infections
  • Thirst
  • Increased urination
  • Purple striations on the skin of the abdomen, thighs, and breasts
  • Mental changes
  • Impotence or cessation of menses
  • Excessive hair growth in females

Exams and Tests

Tests are done to confirm hypercortisolism, then to determine the cause. In general, the fasting glucose may be elevated (glucose intolerance), and serum potassium may be low.

These tests confirm hypercortisolism:

  • 24 hour curine cortisol
  • 24-hour urine creatinine
  • Dexamethasone suppression test (low dose)
  • Serial serum cortisol levels that do not show diurnal variation
  • Nighttime saliva cortisol levels

These tests determine cause:

  • Serum ACTH levels
  • Brain MRI scan that shows a pituitary tumor
  • CRH test
  • Petrosal sinus sampling
  • Dexamethasone suppression test (high dose)

Treatment

Treatment is by surgical removal of the pituitary tumor, if possible. After surgery, pituitary function may slowly return to normal.

A need for hydrocortisone replacement therapy may become apparent during the recovery process. Irradiation of the pituitary gland may also be used.

If the tumor fails to respond to surgery or radiation, medications to inhibit cortisol synthesis are given.

Outlook (Prognosis)

Untreated, Cushing's disease can cause severe illness, even death. Removal of the tumor may lead to full recovery, but regrowth of the tumor can occur.

Possible Complications

  • High blood pressure
  • Diabetes
  • Infections
  • Compression fractures
  • Kidney stones
  • Psychosis

When to Contact a Medical Professional

Call your health care provider if you develop symptoms of pituitary Cushing's.

If you have had a pituitary tumor removed, call if signs of complications occur, including signs of recurrence of the tumor.

 

Pituitary tumor

Definition
A pituitary tumor is an abnormal growth in the pituitary gland, the part of the brain that regulates the body's balance of hormones.

Alternative Names
Tumor - pituitary

Causes
The pituitary gland is a grape-sized endocrine gland located at the base of the brain. The pituitary regulates and controls the secretion of hormones from other endocrine glands, which in turn regulate many body processes. These hormones include the following:

  • Growth hormone (GH)
  • Thyroid-stimulating hormone (TSH)
  • Adrenocorticotrophic hormone (ACTH)
  • Prolactin

About 75% of pituitary tumors secrete hormones. When a tumor produces excessive amounts of one or more hormones, the following conditions may occur:

  • Giantism or acromegaly (excess growth hormone)
  • Hyperthyroidism (excess thyroid stimulating hormone)
  • Cushing's syndrome (excess adrenocorticotropic hormone)
  • Prolactinoma (excess prolactin)

As the tumor grows, destruction of some of the hormone-secreting cells of the pituitary may take place, causing symptoms related to the underproduction of the hormone that is suppressed (hypopituitarism).

The causes of pituitary tumors are unknown, although some are a part of a hereditary disorder called multiple endocrine neoplasia I (MEN I).

There are other types of tumors that can be found in the same area of the head as a pituitary tumor:

  • Craniopharyngiomas
  • Germinomas
  • Cysts
  • Metastatic tumors (tumors that have spread from cancer in another part of the body)

About 15% of tumors located within the skull are pituitary tumors. Most pituitary tumors are located in the anterior pituitary lobe and are usually beningn (noncancerous). Pituitary tumors develop in 1 in 10,000 people.

Symptoms
Because the pituitary gland controls the production of hormones throughout the body, pituitary disorders resemble other endocrine disorders and have a broad range of symptoms. Symptoms depend on the type and location of the tumor and cause hormone excess, hormone deficiency, or pressure on the brain and central nervous system.

Some tumors cause excess hormone production while others cause a deficiency, so one type of tumor may produce symptoms that are very different from those produced by another type of growth (for example, one may cause hair growth while the other causes hair loss).

The same tumor may begin by causing the release of excess hormone and then later result in a deficiency of that hormone as normal pituitary cells are suppressed. This would cause early symptoms that appear to be the opposite of later symptoms.

Some of the many symptoms associated with pituitary tumors include the following:

  • Headache
  • Visual changes
    • Double vision
    • Drooping eyelids
  • Personality changes
    • Decreased sexual interest
    • Irritability
  • Seizures
  • Nasal drainage
  • Skin changes
    • Thickened skin
    • Enlarged sebaceous glands
  • Facial changes
    • Moon face, puffy eyes
    • Enlarged jaw and facial bones
  • Hair changes
    • Loss of body hair
    • Coarse, thin head hair
    • Thinning of eyebrows
  • Weakness
  • Lethargy
  • Temperature sensitivity
    • Intolerance to cold
    • Intolerance to heat
  • Constipation
  • Nausea and vomiting
  • Low blood pressure
  • Impaired sense of smell
  • Changes in weight
    • Weight loss (unintentional)
    • Weight gain (unintentional)
  • In women:
    • Cessation of menses
    • Abnormal nipple discharge
    • Excessive body hair
  • In men:
    • Breast development
    • Impotence

Exams and Tests
Your health care provider will perform a physical examination and will note any double vision and visual field deficits, such as loss of peripheral vision or the ability to see in certain areas.

Tests that help confirm the diagnosis include the following:

  • MRI of head
  • Cranial CT scan
  • Formal visual field testing

Endocrine function tests include the following:

  • Cortisol levels:
    • Urine cortisol test
    • Dexamethasone suppression test - serum cortisol levels measured after giving dexamethasone to supress hormonal secretion
    • Saliva cortisol test
  • Insulin growth factor-1 (IGF-1) levels
  • Thyroid hormone levels:
    • TSH test
    • Free T4 test
  • Serum prolactin levels
  • Testosterone/estradiol levels
  • Leutinizing hormone (LH) levels
  • Follicular stimulating hormone (FSH) levels

Treatment
Pituitary tumors are usually not cancerous and therefore won't spread to other areas of the body. However, they can cause serious problems by putting pressure on the brain. Surgical removal is often necessary, particularly if the tumor is pressing on the optic nerves, which could cause blindness.

Most of the time, pituitary tumors can be removed through a transsphenoidal procedure -- the surgeon accesses the tumor through your nose and sinuses. However, some tumors cannot be removed this way and will require transcranial (through the skull) removal.

Radiation therapy may be used to shrink the tumor, either in combination with surgery or for people who cannot undergo surgery. Medications may shrink certain types of tumors:

  • Bromocriptine or cabergoline are the first-line therapy for tumors that secrete prolactin. These drugs decrease prolactin levels and shrink the tumor.
  • Somatostatin analogs are sometimes used for tumors that secrete growth hormone, particularly when surgery is unlikely to result in a cure.

Outlook (Prognosis)
If the tumor can be surgically removed, the probable outcome is fair to good, depending upon whether the entire tumor was removed.

Possible Complications
The most serious complication is blindness, which can occur if the optic nerve is seriously damaged.

Permanent hormonal imbalances may be caused by the tumor or its removal. This may require replacement of the affected hormones.

When to Contact a Medical Professional
Call your health care provider if you develop any symptoms of a pituitary tumor.