Hyperpituitarism (overactive pituitary gland)
The pituitary gland is the central neuroendocrine gland. Anatomically, it is located in the bony part of the cranial cavity, directly at the base of the brain, like a pendant. Its size is about 1 cm, and its weight is about 0.5 grams. It consists of three lobes, the most important of which are the anterior (adenohypophysis) and posterior (neurohypophysis). The pituitary gland creates a whole series of hormones that regulate the function of other endocrine glands, such as the thyroid gland, adrenal glands, ovaries and testicles, but also other organs and tissues such as the breast, uterus, kidneys and skeletal muscle tissue. It also regulates the formation of the skin pigment melanin and water circulation in the body. The pituitary gland is controlled by the hypothalamus, a part of the brain that belongs to the central nervous system.
Diseases of the pituitary gland follow its anatomical structure, so we distinguish adenohypophysis diseases and neurohypophysis diseases. They can be clinically expressed as primary disorders due to pathological processes within the pituitary gland itself that lead to its reduced (hypopituitarism) or increased function (hyperpituitarism) or as secondary disorders caused by diseases of the hypothalamus.
Enhanced function of the pituitary gland (hyperpituitarism), i.e. the production of excess pituitary hormones, is most often caused by an increase in pituitary tissue or the formation of functional tumors that produce different hormones. Most often, we speak about adenomas (prolactinoma, somatotropinoma, corticotropinoma and thyrotropinoma). Their size can be
< 10 mm (microadenomas) or > 10 mm (macroadenomas). Due to the growth of tumors and their pressure on bones, blood vessels, nerves and brain tissue, complaints often include headaches, dizziness, visual field failures with impaired vision, destruction of the brain or bony structures of the skull, paralysis of the cranial nerves and thrombosis of the venous sinuses of the skull. In addition to the above, there are a number of other symptoms that are specific to each hormonal excess.
- An excess of the prolactin hormone (PRL) is manifested by milky discharge from the breasts (galactorrhea), reduced ovarian and testicular function, sterility and cessation of menstruation.
- An excess of growth hormone or somatotropin (GH) results in the growth and thickening of the extremities (hands, feet, jaw) of the nose, lips, tongue, muscles, heart, thyroid, kidneys, liver. Increased sweating, oily skin, chronic joint changes, nerve damage and weakening of heart and kidney function occur. In addition to the above, there is also an increased frequency of high blood pressure, diabetes, polyps and colon cancer.
- An excess of thyroid-stimulatin hormone or thyrotropin hormone (TSH) leads to increased stimulation of the thyroid gland, which results in its increased function (hyperthyroidism). Patients usually present with symptoms of accelerated metabolism (sweating, increased appetite with weight loss, intolerance to heat). Other complaints include general weakness, restlessness and hyperreactivity, irritability and nervousness, frequent urination and diarrhea, sleep disturbance, bulging of the eyeballs (exophthalmos), rapid heart rate with palpitations, increased blood pressure, heart rhythm disorders, neurological symptoms (muscular weakness, hand tremors, loss of consciousness), eye irritation and skin changes.
- An excess of the adenocorticotropic hormone (ACTH) leads to an increased function of the adrenal glands, i.e. the production of an excess of their own hormones: aldosterone, corizone and sex hormones (adrenal androgens). Disruption of ovarian and testicular function occurs, infertility, reduction of libido and potency with a decrease in the size of the testicles, weight gain, decrease in the size of muscles on the upper and lower extremities, skin changes with the appearance of bleeding on the skin (hematomas), increased acne formation, increased hairiness. There is also an increase in blood pressure, sugar and fat in the blood along with osteoporosis and an increased tendency to infections. Psychological problems in the form of anxiety or depression are also common.
Diagnostic procedure and therapeutic approach
The diagnostic procedure includes a specialist examination, laboratory and hormonal tests, genetic testing and additional diagnostic methods that often include MR imaging, ophthalmological and neurological examination. The therapeutic approach is based on drug treatment, targeted radiation (gamma-knife) and surgical removal of the pituitary tumor.