Brief overview
- Symptoms: headache, nausea, vomiting, muscle paralysis, hydrocephalus, visual disturbances, milk let-down without pregnancy, loss of potency, growth disorders, osteoporosis, overweight or underweight, weakness, fatigue, edema, psychological disorders such as depression and anxiety
- Treatment: Surgery, radiation and drug therapy.
- Prognosis: If treated early, especially the benign forms, the prognosis is usually good. If left untreated, some pituitary adenomas are fatal.
- Diagnosis: magnetic resonance imaging (MRI), computed tomography (CT), blood, saliva, and urine tests.
- Causes: The triggers of the cell changes are not known. There appears to be an increased risk in association with multiple endocrine neoplasia type 1 (MEN1).
What is a pituitary adenoma?
A pituitary adenoma is a rare, benign tumor of the pituitary gland in the skull. It accounts for about 15 percent of all brain tumors. The disease occurs in all age groups, usually diagnosed by the doctor between the ages of 35 and 45.
Forms of pituitary adenoma
The pituitary gland produces various messenger substances (hormones, endocrine substances) with the help of different glandular cells. It is possible for a pituitary adenoma to arise in principle from any of these different glandular cells and subsequently cause overproduction of the hormone in question. Approximately 60 percent of all patients have such an endocrine-active pituitary adenoma.
In 60 to 70 percent of cases, the cells produce increased amounts of the breast milk-promoting hormone prolactin. This pituitary tumor is called a prolactinoma. Somewhat less frequently, at about five to ten percent, the pituitary gland secretes increased amounts of the growth hormone. In about five percent of cases, adrenocorticotropic hormone (ACTH) is affected by overproduction. Very rarely, a pituitary adenoma affects the production of thyroid and sex hormones.
In addition to these endocrine-active tumors, there are also those that do not affect hormone production. In about 40 percent of all affected individuals, the pituitary adenoma remains endocrine inactive.
What are the symptoms of a pituitary adenoma?
General brain tumor symptoms such as headache, nausea, vomiting, muscle paralysis, and hydrocephalus usually first appear with a large pituitary adenoma.
If the pituitary adenoma presses on the optic nerve, visual disturbances develop. Often, the outer visual fields fail at first. Some affected individuals have blurred or double vision. With a pituitary adenoma, such visual problems are not necessarily continuous. They change, for example, and vary in severity. However, due to larger tumors, some affected individuals even go blind.
The pituitary gland produces six different hormones in response to signals from its higher-level center (hypothalamus). These stimulate other hormone glands in the body (such as the thyroid or adrenal glands) to produce hormones in turn. In this way, the hypothalamus and pituitary gland regulate the release of various hormones in the body.
A pituitary adenoma impairs the function of the hypothalamus and/or pituitary gland. Then they may produce too many or too few hormones. As a result, different complaints occur. Although the cause of all these complaints is a pituitary adenoma, some clinical pictures are given their own name, such as prolactinoma, acromegaly and Cushing’s disease (see below).
Prolactin and sex hormones
In addition, it is possible that the female (estrogens) and male (testosterone) sex hormones are affected by a prolactinoma or other pituitary tumor. In women, this may cause menstrual periods to occur irregularly or stop altogether. In some, physical pleasure (libido) decreases. Men sometimes have trouble building an erection (loss of potency).
Growth hormones
Growth hormone from the pituitary gland is not only important for body growth and development in children. In adults, it also controls essential body functions such as bone, fat and muscle metabolism. If the pituitary gland produces too much growth hormone due to a pituitary adenoma, the body grows. In children in the growth phase, this is referred to as tall stature (gigantism).
In adults, most of the growth plates of the bones are already closed. In adults with a growth hormone-producing pituitary adenoma, the hands and feet in particular increase in size and the facial features coarsen (acromegaly). If the jaw grows, the teeth move apart. In addition, affected individuals often sweat more. In some sufferers, a hand nerve is pinched (carpal tunnel syndrome), which causes pain.
Hormones of the adrenal cortex
The pituitary gland also stimulates the adrenal gland with the control hormone adrenocorticotropic hormone (ACTH). This releases cortisol (a stress hormone), aldosterone (a hormone for salt and water balance) and sex hormones as needed. If a pituitary adenoma disrupts this hormone production, it alters complex processes in the body – especially fat, bone, sugar, salt and fluid metabolism.
If a pituitary adenoma produces too much ACTH, Cushing’s disease develops. Signs of the disease are overweight (obesity), a full moon face (facies lunata), stretch marks on the upper body, high blood pressure, diabetes mellitus, osteoporosis, water retention in the tissues (edema), psychological symptoms such as depression and anxiety.
On the other hand, if a pituitary adenoma suppresses ACTH production, weakness, fatigue, weight loss, nausea and vomiting occur.
Thyroid hormones
In rare cases, a pituitary adenoma alters thyroid function. The thyroid hormone thyroxine has a similar effect to gasoline for a car. It powers many organs and gets the body moving. If it is produced in excessive amounts due to a pituitary adenoma, the heart beats faster than normal, you sweat, and the bowels work harder. Diarrhea and fever sometimes occur.
Antidiuretic hormone
Antidiuretic hormone (ADH) controls fluid balance in the body. It ensures that not too much water is lost through the urine. As a result, it also influences the concentration of blood salts and blood pressure. The hypothalamus produces ADH, while the pituitary gland stores it and releases it when needed.
A pituitary adenoma, which involves the hypothalamus, impairs ADH metabolism. With too little ADH, affected individuals suffer from diabetes insipidus: they excrete many liters of water-clear urine (polyuria). To avoid dehydration, they drink a correspondingly large amount.
Is a pituitary adenoma curable?
If a pituitary adenoma does not cause any symptoms, treatment is not necessarily required. In this case, the doctor checks at certain intervals with an imaging examination (according to the motto “wait and scan”) whether the tumor is growing and requires treatment.
Which therapy is considered for a pituitary adenoma varies from individual to individual. As a rule, all physicians involved, including specialists in hormonal diseases (endocrinologists), discuss together with the affected person which treatment makes the most sense. In principle, a pituitary adenoma can be operated on, irradiated and treated with medication.
Surgery
During surgery, there is a risk of damaging surrounding structures such as vessels, nerves or the pituitary gland itself, which then requires further therapeutic measures and comprehensive follow-up care.
For more information on examinations and treatment, read the article Brain Tumor.
Drug treatment
Not all patients with a pituitary adenoma require surgery. Hormone-producing pituitary tumors such as prolactinoma can sometimes be treated well with medication. In addition, drug therapy is often used before surgery and when a hormone circuit is permanently damaged after treatment. ADH, thyroid, growth, sex, and stress hormones can be replaced by drugs if they are deficient (hormone replacement therapy).
However, since the body produces and secretes the hormones in varying amounts during the course of the day and depending on the respective phase of life, this therapy is not entirely simple. In order to optimally adjust the dose, different values in the body must be determined, sometimes at different times of the day. Also, in certain situations, such as stress or infections, affected individuals sometimes take more or less medication than usual. The doctor therefore monitors hormone therapy regularly.
What is the course of a pituitary adenoma?
If hormone changes persist for a long time, many different organs in the body may be damaged. Undetected hormone disorders caused by a pituitary adenoma are sometimes fatal.
How is a pituitary adenoma diagnosed?
If a pituitary adenoma is suspected, doctors from different specialties work together to find out for sure.
Radiologists produce images of the head using magnetic resonance imaging (MRI) or computed tomography (CT). On these, they can see whether a tumor is actually present and exactly where it is located. Tumor size and any calcifications can also be seen in these imaging procedures. The neurologist examines the patient if muscle paralysis or headaches occur. If there are visual disturbances, an ophthalmologist is the right person to contact.
Endocrinologists are particularly important in cases of pituitary adenoma. They will ask for a description of the symptoms of the affected person and consider whether a particular hormonal circuit is impaired. The individual hormone concentrations and other parameters that are important in a pituitary adenoma can be measured in the blood, saliva and urine of the sufferer. This is how doctors find out which hormone gland is impaired. Even after treatment, people with a pituitary adenoma are regularly examined by endocrinologists.
What triggers a pituitary adenoma?
A pituitary adenoma develops when individual glandular cells of the pituitary gland degenerate and begin to grow uncontrollably. It is not yet clear why this happens.
A pituitary adenoma develops in about 20 percent of people with multiple endocrine neoplasia (MEN1). This is an inherited disease in which multiple endocrine glands are abnormally altered due to a genetic defect. There appears to be a link between the two diseases.
