The pituitary gland is complex in that it affects various parts of the body with many different hormones. Pituitary diseases that cause either an over-secretion or under-secretion of one or more of those hormones can have a wide variety of health effects and appear as any one of several pituitary disorders.
The posterior (back) lobe of the pituitary gland releases ADH (antidiuretic hormone) and oxytocin (a hormone to contract the uterus during childbirth and stimulate milk production). Antidiuretic hormone (ADH), which is also called vasopressin, helps the kidneys (and body) conserve the right amount of water. For example, when a person becomes dehydrated, more ADH is produced to help the body conserve the water it contains. Lack of ADH leads to too much excretion of water (diabetes insipidus), and too much ADH leads to excessive retention of water by the body (syndrome of inappropriate antidiuretic hormone secretion).
The anterior (front) lobe of the pituitary gland makes up 80 percent of the gland's weight. It releases a variety of hormones that affect growth, physical and sexual development, and other endocrine glands. Over-secretion or under-secretion of certain hormones by the anterior lobe of the pituitary gland will cause other endocrine glands to over or under-produce certain hormones, as well, resulting in a variety of pituitary disorders.
Some pituitary diseases and pituitary disorders are caused by pituitary tumors. Researchers do not know at this time what causes pituitary tumors. However, research studies show that having a hereditary condition such as multiple endocrine neoplasia type I (MEN 1) increases the risk of developing pituitary tumors, parathyroid tumors and pancreatic tumors.
Pituitary diseases can have symptoms that appear gradually or suddenly. Symptoms of both overproduction or underproduction of hormones secreted from the pituitary gland may resemble other conditions or medical problems.
Pituitary disease symptoms include:
- Vision problems
- Irregular menstrual periods
- Abnormal breast milk production
- Decreased body hair
- Enlarged breasts
- Buildup of fat in the face, back and chest
- Weakened bones
- Rapid growth
- Profuse sweating
Prolactinomas (benign tumors of the pituitary gland) can cause prolactin to be overproduced. High prolactin levels can cause menstrual periods in women to be irregular or stop, and can cause galactorrhea (abnormal breast milk production). Men suffering from this pituitary disorder may experience impotence (erectile dysfunction, or ED) or a lack of interest in sex. Men may also have enlarged breasts, infertility or a decrease in body hair. If these symptoms go unrecognized and progress, headaches and vision problems can occur.
These tumors are the most common type of tumor and pituitary disorder. They do not secrete an extra amount of hormone and until they become a certain size, the person shows no symptoms of pituitary disorders. As the tumor grows, an individual may begin to suffer headaches and vision problems.
Cushing's syndrome is the result of the excessive production of corticosteroids by the adrenal glands. An overproduction of corticotropin (the hormone that controls the adrenal gland by the pituitary gland, which stimulates the adrenal glands to produce corticosteroids) may be one cause. In addition, certain lung cancers and other tumors outside the pituitary gland may produce corticotropins. Other causes include benign or cancerous tumors on the adrenal glands.
Acromegaly is the Greek word for "extremities" and "enlargement." When the pituitary gland produces excess growth hormones the result is excessive growth, called acromegaly. The excessive growth occurs first in the hands and feet, as soft tissue begins to swell. This rare pituitary disease affects mostly middle-aged adults. Untreated, the pituitary disorder can lead to severe illness and death.
Also called an underactive pituitary gland, hypopituitarism is a pituitary disorder that affects the anterior (front) lobe of the pituitary gland, usually resulting in a partial or complete loss of function in that lobe. The resulting symptoms depend on which hormones are no longer being produced by the gland. Because the pituitary gland affects the other endocrine organs, effects of hypopituitarism may be gradual, or sudden and dramatic.