Pituitary gland diseases
Pituitary gland diseases
The pituitary gland, or the hypophysis, is the controlling organ of the entire endocrine system. It includes all organs with internal secretion, such as the thyroid, adrenal glands, a part of pancreas and other. The role of this system is the production of hormones, which are chemicals used for information transfer. They get to the target tissues through the blood stream. The pituitary gland is divided into two parts. Anterior, adenohypophysis and the posterior part, neurohypophysis. In both of these parts, lobes, dysfunction may occur causing pituitary diseases.
Anterior and posterior lobes of the pituitary gland
Pituitary gland diseases affect both the anterior and posterior lobes of the pituitary gland. In the anterior lobe, adenohypophysis, more hormones are produced. Most of them are those that affect the production of chemical messengers in other endocrine glands. These include thyrotropin (affecting the thyroid gland), adrenocorticotropin (affecting the adrenal glands), gonadotropins (affecting the genitals), prolactin (important for lactation) and growth hormone. Neurohypophysis is only a storage of hormones from the hypothalamus, like oxytocin (which is necessary for childbirth and lactation) and vasopressin, or antidiuretic hormone (which affects the reabsorption of water from the urine by the kidneys).
Causes of pituitary gland diseases
Pituitary gland diseases may not have any distinct symptoms. In the case of symptom appearance we are talking about syndromes – like hypopituitarism, a condition characterized by insufficient production and secretion of one or more pituitary hormones. Furthermore, increased levels of these hormones or tumors pressing on the surrounding structures impair their activities. The most common cause of pituitary diseases is benign tumors (adenomas). These can either be a source of increased hormone production (active tumors), or can be endocrine-inactive, or oppress by their growth the surrounding tissue and thus prevent the production of sufficient amounts of hormones. Active tumors are typically made from one type of a cell, thus they preferentially secrete one substance. Quite common are tumors called prolactinomas, which result in the production of milk outside of pregnancy or cause infertility. Adenoma from cells producing growth hormone results in gigantism or acromegaly. Gigantism occurs in children, who do not have yet completed bone growth, while acromegaly occurs in adults, where the bones can no longer grow in length, which leads to their thickening. These pituitary diseases affect many internal organs and interfere with their proper functions, thus these diseases are very serious. Overproduction of adrenocorticotropic hormone causes Cushing's disease. Its symptoms are very diverse; the main ones include increased blood sugar levels, reduced immunity, increased blood pressure and impaired general body ability to cope with stress. In addition to tumors pituitary diseases can be caused by injuries, stroke, radiation, inflammatory processes, etc. Congenital pituitary diseases do not occur very often, however, in these cases a part of the tissue from this organ may be missing.
Treatment of pituitary diseases
For the diagnosis of pituitary diseases imaging techniques are mainly used – like CT scan or magnetic resonance. In the case of a tumor it is not possible to definitively determine what type it is, only after surgery, when the sample is sent for microscopic examination. Laboratory tests definitely help in the diagnosis of pituitary diseases before surgery by detecting an increase or decrease of the levels of pituitary hormones in the blood. In some cases, after removal of the tumor the condition switches in to another extreme, i.e. lack of pituitary hormones - hypopituitarism. In some adenomas irradiation is therefore safer, to stop further growth of the tumor. It is necessary to be careful because of the very close proximity of the optic nerves, so that the treatment does not damage them.