20% May Have Tumor on Pituitary, Study Finds
One in five adults may have a noncancerous tumor on their pituitary, a pea-sized gland in the brain that plays a central role in regulating the body’s hormones, according to research released Friday. At least one in three of those tumors may cause significant clinical problems.
The finding, presented in San Antonio at the annual meeting of the American Assn. of Clinical Endocrinologists, should not be a cause for alarm, says endocrinologist Dr. Keith Friend, who coordinated the research.
“We don’t want to scare people; these are benign tumors,” stressed Friend, currently a research scientist with Pharmacia Corp. in New Jersey.
However, he added, the tiny growths can alter the production of hormones in the body and cause an array of complaints. They range from serious but treatable conditions like Cushing’s syndrome to milder symptoms such as loss of libido. These milder complaints, even if not life threatening, can cause much distress. Yet often, a pituitary tumor remains undiagnosed for years.
The finding of so many benign tumors “should raise our awareness of pituitary disease, so that doctors and patients recognize it’s common and doctors think of it when patients come in with complaints,” said Dr. Sylvia Asa, a professor at the University of Toronto and incoming president of the Pituitary Network Assn., an advocacy group based in Thousand Oaks.
The pituitary gland sits at the base of the brain roughly behind the bridge of the nose and is known as the “master gland” because it produces many hormones and regulates the production of other hormones elsewhere in the body.
The hormones the pituitary secretes are involved in things such as body growth and maintenance, response to stress, reproduction and sexuality.
Normally, the pituitary gland consists of a mixture of cells producing various hormones. Sometimes a noncancerous tumor develops from a cell making one kind of hormone. As that tumor grows, it pumps out extra amounts of that hormone. Other kinds of tumors can impede the production of hormones.
Various conditions can develop from a pituitary tumor. Overproduction of a hormone called ACTH causes Cushing’s syndrome, in which the body is exposed to high levels of the stress hormone cortisol. The condition causes changes such as obesity, depression and diabetes.
Overproduction of growth hormone, meanwhile, causes acromegaly, with symptoms including enlargement of hands, feet, forehead and inner organs, reduced sexual drive, hypertension and diabetes as well as a heightened risk of developing colon cancer.
Other symptoms that can be caused by pituitary tumors include lethargy, memory problems, impotence, abnormal secretion of fluid from the breasts, headaches, vision problems and irregular menstrual periods and infertility.
Endocrinologists don’t know for sure how often pituitary tumors cause clinical symptoms.
In the study reported Friday, a group led by Friend (then at the University of Texas M.D. Anderson Cancer Center in Houston) assessed the prevalence of pituitary tumors in about 10,000 people. They did so by gathering data from 12 earlier studies in a technique known as a meta-analysis.
In some of the studies, pituitaries were examined during autopsies. In others, brains of living patients were scanned. None of the 10,000 people had been identified as having symptoms of a pituitary tumor and were thus considered good estimates of the tumor prevalence in the general population.
Tumors were identified in 20% of the pituitaries examined. In one-third of the cases, there was evidence that the tumors were over-producing one or more pituitary hormones at a level that might be expected to cause disease, Friend said.
The high rate of hormone-producing tumors is particularly newsworthy, said Dr. Daniel Kelly, director of the UCLA pituitary tumor and neuroendocrine program. Such tumors, in general, “are not high on doctors’ radar screens because the symptoms they produce are attributable to many other things,” he said.
Good ways exist to treat such a tumor, Kelly said--including replacement hormones, drugs to shrink it, radiation, and surgery to remove the extra growth.
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Hormonal Imbalance
The pituitary gland, a pea-sized structure at the base of the brain, is a “master gland” that makes many important hormones. Tiny, benign pituitary tumors can cause certain hormones to be over- or under-produced. For more information, go to www.pituitary.org.
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Source: American Medical Assn. Encyclopedia of Medicine
