Pituitary Adenomas and Hormone Disorders
There are two main systems that control the body's functions. The first of these is the “nervous system”, which originates in the brain and spinal cord and is distributed throughout the body, and the second is the “hormonal system” or “endocrine system”, which manages the functions of the body by traveling in the blood that constantly circulates in the body. These two systems work in conjunction with each other. Hormones are chemical substances secreted by cell communities or glands in the body. There are two glands in the brain that belong to the endocrine system. The first is the pituitary gland and the second is the pineal gland. While tumors involving the pineal gland are very rare, tumors involving the pituitary gland are found in 5-10% of all brain tumors.
Pituitary gland tumors have a harmful effect on the body in two ways. The first harmful effect occurs when it exceeds its normal size and compresses the surrounding structures. In this case, especially the optic nerve near the gland is affected, resulting in decreased vision or loss of vision in the patient. If the tumor grows larger, loss of function of the nerves that make eye movements may also occur. When the pituitary gland reaches such a large size, the normal pituitary tissue loses its function and there may be a deficiency in various hormones secreted from the pituitary gland. Tumors that produce the first effect are called macroadenomas. The second harmful effect of the tumor is the excessive secretion of certain hormones with or without enlargement of the pituitary gland. If the pituitary gland is enlarged to a size not exceeding 1 cm, these tumors are called microadenomas. The pituitary gland consists of two parts: anterior pituitary and posterior pituitary. Pituitary gland tumors are mainly tumors of the anterior pituitary.
The hormones secreted from the anterior pituitary and their functions are as follows:
- The hormone prolactin ensures the secretion of milk from the breast.
- Growth hormone controls carbohydrate, fat and protein metabolism in the body. It ensures balanced growth of the body, especially during puberty.
- Adrenocorticotrophic hormone regulates the vital secretion of cortisol from the adrenal glands.
- Thyroid stimulating hormone regulates the secretion of thyroid hormones from the thyroid gland.
- Gonadotrophic hormones control the function of the reproductive organs.
When cell groups in the pituitary gland that secrete one or two of the hormones listed above secrete more hormones than the body needs, the functions of that hormone or hormones in the body increase. For example, if excessive prolactin is secreted, the patient may produce milk from her breasts even though she is not pregnant. If excessive growth hormone is secreted in an adult, shoes may start to fit tightly as a result of excessive growth of the body. The posterior pituitary secretes antidiuretic hormone, which regulates urine output from the body, and oxytocin, which causes uterine contraction during labor. Tumors of the posterior pituitary are almost never seen.
There are three approaches to the treatment of pituitary tumors: Medication, surgery and radiation therapy. It is possible to control excessive hormone secretion with medication. However, when the medication is stopped, hormone secretion returns to its previous level in most patients. For example, in a tumor that secretes excessive prolactin, if the patient wants to become pregnant, the medication must be discontinued because it may have side effects on the baby. This makes it easier for the tumor to grow again. The patient may need to take the medication for the rest of her life.
The aims of surgical treatment are: To remove the pressure of the tumor on the surrounding tissues, such as the optic nerves, to reduce the tumor mass and to provide a better response to drug treatment. Surgical treatment is also necessary for tumors that do not respond to medication. In cases such as macroadenoma causing sudden loss of vision or bleeding into the tumor, surgery should be performed immediately.
Surgical treatment is mainly performed in two ways. The first is a transsphenoidal nasal route and the second is to open the skull bone from above and remove the pituitary tumor.
Radiation therapy is preferred for pituitary tumors that cannot be controlled with medication and surgery or that extend to a risky place to be reached with surgery.
