Pituitary Tumors (Adenomas): What They Are, Causes, Symptoms, and Treatment

Each organ that makes up the hormone system plays vital roles for our body.

Each organ that makes up the hormone system plays vital roles for our body. Therefore, various diseases affecting the endocrine system can lead to serious clinical complaints. In this regard, one of the hormone system diseases that can be observed in the community, which may present with different clinical manifestations, is the formation of tumors called adenomas in the pituitary gland.

What is the Pituitary Gland?

The pituitary gland is a hormone-producing gland about the size of a walnut, located at the base of the brain within the skull, in a region adjacent to the nasal cavity. It resides within a protective bony structure called the Sella Turcica (Turkish Saddle). Signals from the upper centers of the brain are first transmitted to the Hypothalamus, and from there, through the pituitary stalk, they are conveyed to the pituitary gland, where the hormones necessary for the body are secreted. In other words, the pituitary gland forms the fundamental control point of the hormone system. The hormones produced by the pituitary gland regulate the function of other hormone glands, thus indirectly controlling the function of internal organs.

The pituitary gland is divided into three parts: anterior, posterior, and intermediate pituitary. Essentially, hormone production occurs in the anterior pituitary. The intermediate pituitary only produces melanocyte-stimulating hormone. The posterior pituitary is in communication with the hypothalamus and produces two different hormones.

1. Anterior Pituitary
   The anterior pituitary is responsible for producing six different hormones and is directly related to the endocrine system. The following hormones are produced by the anterior pituitary:

• Growth Hormone (GH): It affects the whole body, helping to mature and grow organs during the growth and development period; in adulthood, it aids in the continuity of cell functions throughout the body.
• Adrenocorticotropic Hormone (ACTH): It is responsible for regulating the production of vital hormones such as cortisol, aldosterone, and androgen derivatives, which are secreted by the adrenal glands.
• Thyroid-Stimulating Hormone (TSH): It regulates the production of thyroid hormones, which are vital for the body.
• Follicle-Stimulating Hormone (FSH): In women, FSH is responsible for the development of reproductive cells in the ovaries; in men, it plays a role in regulating sperm production. It also regulates the production of sex hormones like estrogen, progesterone, and testosterone.
• Luteinizing Hormone (LH): In women, LH helps release mature egg cells into the reproductive tract; in men, it is responsible for sperm production and maturation. Together with FSH, it regulates the production of sex hormones.
• Prolactin: In women, prolactin is the primary hormone responsible for milk production after childbirth. It also plays a role in regulating the reproductive system and has various psychological effects.

2. Posterior Pituitary
   The posterior pituitary is responsible for the production of two different hormones and has a tissue structure that directly connects with the hypothalamus:

• Antidiuretic Hormone (ADH): It stimulates water retention in the kidneys, regulating urine volume and the body's water balance.
• Oxytocin: In women, oxytocin triggers labor contractions and helps the uterus shrink after birth, stopping post-birth bleeding. It also helps release breast milk from the mammary glands through pressure.

What is a Pituitary Tumor?

A pituitary adenoma is the formation of a mass caused by the uncontrolled division and proliferation of the cells that make up the tissue of the pituitary gland for various reasons. Although pituitary adenomas are benign tumors in terms of their functions and structures, they can cause various clinical symptoms and negatively affect health depending on the size they can reach and their functionality. Very rarely, pituitary tumors can become cancerous. Pituitary adenomas observed in clinical practice are usually derived from the anterior pituitary.

The clinical symptoms of pituitary adenomas vary depending on whether they produce hormones and their tumor size, which is related to the pituitary cell from which they originate. Adenomas smaller than 1 cm in diameter are called microadenomas, while adenomas larger than 1 cm are called macroadenomas. Although microadenomas often do not cause significant issues in surrounding tissues, macroadenomas can create problems through compression of anatomical structures near the pituitary and the pituitary gland itself.

In addition, adenomas may be functional and produce certain hormones in excessive amounts in an uncontrolled manner, depending on the cells they originate from. In this regard, adenomas can produce growth hormone, ACTH, TSH, prolactin, FSH, or LH. Tumors originating from different tissue types related to the embryonic period in the mother’s womb may also develop in or around the pituitary gland (such as craniopharyngiomas, teratomas, gangliocytomas).

In light of this information, the majority of pituitary adenomas encountered in clinical practice are of the microadenoma type and are prone to producing prolactin. On the other hand, most tumors observed as macroadenomas are non-functional and do not produce any hormones. They develop clinical symptoms through compression of surrounding tissues.

What Causes Pituitary Tumors?

In current clinical practice, the exact cause of pituitary adenomas is not fully understood. However, research has shown that there is a higher likelihood of developing pituitary adenomas in patients with certain risk factors. These factors are genetic and can be summarized as follows:

• Patients with Multiple Endocrine Neoplasia Syndrome Type 1 (MEN-1)
• Patients with McCune-Albright Syndrome
• Patients with Carney Complex
• Individuals with a family history of pituitary adenomas

What Are the Symptoms of a Pituitary Tumor?

Symptoms associated with pituitary tumors may arise from pressure on surrounding tissues due to the tumor's size, or they may occur due to a functional deficiency in the pituitary gland, leading to hormonal imbalances. If the tumor is a functional mass producing hormones, symptoms related to the excess of those hormones may also develop. Therefore, it would be more logical to ask, "What are the symptoms associated with pituitary tumors?"

In this context, when pituitary adenomas reach large sizes, the following symptoms can occur due to pressure on surrounding tissues:

• Vision loss or reduction in the visual field (especially loss in the outer quadrants of the eye)
• Headaches
• Nausea and vomiting
• Weakness, fatigue, irregular periods, sexual dysfunction, increased urine output, weight gain due to pressure on the pituitary gland

Additionally, if the adenoma has functional characteristics, the following symptoms may be added to the clinical picture due to the increased hormone levels:

• In cases of prolactin excess: Irregular periods or complete cessation of menstruation, milk discharge from the breast tissue, sexual dysfunction in men, decreased sperm count, breast tissue development
• In cases of growth hormone excess: Excessive growth during childhood; in adulthood, elongation of body parts such as the jaw, nose, hands, and feet, sweating, high blood sugar, joint and heart problems
• In cases of ACTH excess: Abnormal fat accumulation in certain areas of the body, muscle weakness, high blood pressure and blood sugar, oily skin and acne, stretch marks, psychological problems
• In cases of TSH excess: Weight loss, palpitations, digestive issues, sweating, restlessness, and irritability
• In cases of FSH-LH excess: Irregular periods, sexual dysfunction, infertility

How is Pituitary Tumor Diagnosed?

Since pituitary tumors can lead to a wide range of clinical scenarios, a detailed medical history and physical examination conducted by a specialist, along with data obtained from additional imaging and laboratory tests, are combined. Based on these investigations, the presence and characteristics of the adenoma are identified, leading to a diagnosis.

The tests typically conducted include hormone tests in blood and urine, imaging of the brain area using methods like computed tomography (CT) and magnetic resonance imaging (MRI), and visual field tests.

How is Pituitary Tumor Treated?

The treatment approach for pituitary tumors is primarily determined based on the clinical findings in the patient and the level of impact on health. In this context, tumors with microadenoma characteristics that do not cause functional or anatomical problems may not require treatment. However, larger and functional tumors may require different treatment methods. The following methods are used in the treatment of pituitary tumors:

• Monitoring: For small, non-functional tumors that do not cause clinical symptoms, close monitoring may be recommended. In such cases, patients are periodically evaluated for any changes in tumor behavior or size.
• Surgery: Tumors that cause compression symptoms may require surgical removal of the adenoma. Two different methods can be applied. The first method, called endoscopic transnasal transsphenoidal approach, involves removing the tumor through a closed technique with endoscopes inserted into the nose. The second method is a transcranial approach, which involves removing the tumor via open brain surgery.
• Radiotherapy: After surgery or in cases where surgery is not possible, the tumor can be treated with radiotherapy using concentrated X-rays. External radiotherapy or stereotactic radiosurgery techniques may be used.
• Medication: Various medications can be used to alleviate symptoms caused by changes in the levels of pituitary hormones in the blood, such as excess or deficiency of these hormones.