Hypopituitarism (underactive 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 g. It consists of three lobes, the most important of which are the front (adenohypophysis) and the back (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.
Reduced function of the pituitary gland (hypopituitarism), i.e. reduced production and secretion of pituitary hormones is most often caused by pituitary tumors, other tumors that grow near it (craniopharyngiomas, cysts, neurinomas), brain tumors, tumor metastases in the cranial cavity, conditions after neurosurgical interventions in the skull, radiation, accumulation diseases (hemochromatosis, amyloidosis), autoimmune diseases, granulomatous diseases (sarcoidosis, histiocytosis, tuberculosis), inflammation of the pituitary gland, circulatory disorders in the pituitary gland (apoplexy, postpartum necrosis) and head and brain trauma. The symptoms are specific for each hormonal deficiency:
- Lack of growth hormone or somatotropin (GH) causes episodes of general weakness with loss of strength along with low blood sugar (hypoglycemia), fatigue and slowed red blood cell (erythrocyte) production.
- Lack of thyroid-stimulatin hormone or thyrotropin hormone (TSH) leads to reduced thyroid function (hypothyroidism). The disease is most often presented by fatigue, dry and thin skin, increased hair loss, difficulties with concentration, signs of slowed metabolism, increased feeling of cold, weight gain, lowered mood, digestive and menstrual cycle disorders.
- Deficiency of the hormones follitropin (FSH) and luteotropin (LH) results in reduced ovarian and testicular function. Sexual dysfunction occurs (loss of libido and potency), the menstrual cycle and the production of other sex hormones are disrupted.
- Lack of adenocorticotropic hormone (ACTH) results in reduced function of the adrenal glands. Episodes of low blood sugar (hypoglycemia), fatigue, weakness, hair loss, low blood pressure, nausea, vomiting, general sluggishness, pale skin can occur.
- A lack of antidiuretic hormone or vasopressin hormone (ADH) leads to the creation of an extreme amount of urine with a pronounced feeling of thirst with intake of up to 20 liters of fluid/day.
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, as well as ophthalmological and neurological examination. The therapeutic approach is based on the replacement of hormones in deficiency and the treatment of basic diseases that cause reduced function of the pituitary gland.