The pituitary gland is a small gland located at the base of the brain, but it plays an essential role in the body’s hormonal balance.
Pituitary adenomas are relatively common tumors, and it is estimated that clinically significant ones affect approximately 1 in every 1,000 people. Most are benign and grow slowly; however, depending on their size and whether they produce excess hormones, they can affect vision, metabolism, sexual function, growth, or other bodily functions.
Below, we’ll explore what a pituitary adenoma is, what its symptoms are, how the diagnosis is confirmed, and what treatment options are considered in each case.
What is a pituitary adenoma?
A pituitary adenoma is a tumor that originates in the pituitary gland. This gland produces hormones that help regulate functions such as growth, thyroid activity, fertility, stress response, and breast milk production.
In most cases, it is a benign tumor, meaning it does not spread to other parts of the body. Even so, it may require monitoring or treatment if it grows, disrupts hormone production, or puts pressure on nearby structures, such as the optic nerves.
Pituitary adenomas can be classified according to their size:
- Microadenomas: measure less than 1 centimeter.
- Macroadenomas: measure 1 centimeter or more and are more likely to put pressure on nearby structures.
They can also be functioning—when they produce one or more hormones in excess—or non-functioning—when they do not produce an excessive amount of hormones, although they may cause symptoms due to compression.
Main Symptoms of Pituitary Adenoma
The symptoms of a pituitary adenoma depend mainly on two factors: whether the tumor produces excess hormones and whether, due to its size, it compresses nearby structures.
For this reason, not everyone experiences the same symptoms. In some cases, the adenoma is detected incidentally during an imaging test performed for another reason.
Hormonal Symptoms
When the adenoma produces excess hormones, symptoms may vary depending on the hormone involved:
- Elevated prolactin: menstrual irregularities, difficulty becoming pregnant, milk secretion from the breasts without pregnancy or breastfeeding, decreased sex drive, or erectile dysfunction.
- Excess growth hormone: enlargement of the hands, feet, or facial features in adults, as well as excessive sweating, joint pain, or changes in the voice.
- Excess corticotropin (ACTH): may increase cortisol production and lead to Cushing’s disease, with weight gain in the trunk, a rounder face, purplish stretch marks, frequent bruising, muscle weakness, or mood swings.
- Excess TSH or thyrotropin: In rare cases, it can increase the production of thyroid hormones and cause symptoms of hyperthyroidism, such as weight loss, palpitations, nervousness, or heat intolerance.
In some non-functioning adenomas, the tumor may interfere with normal pituitary hormone production. This can cause fatigue, loss of energy, weight changes, intolerance to cold or heat, and decreased sexual function, and in some cases may require hormone replacement therapy.
Symptoms Due to Compression
As the adenoma grows, it can put pressure on nearby structures. The most common symptoms are:
- Persistent or new-onset headache.
- Visual disturbances, especially loss of peripheral vision or changes in the visual field.
- Double vision in some cases.
- Nausea or vomiting, although these do not always occur.
- Fatigue or weakness related to hormonal changes.
Visual disturbances require urgent medical evaluation, as they may indicate that the tumor is affecting the optic nerves or the optic chiasm, a structure related to the visual field.
Causes and Risk Factors
The causes of pituitary adenoma are not always known. In most patients, no specific cause is identified, nor is there anything they have done to trigger its development.
In general, it is believed that genetic changes in some pituitary cells may be involved, causing them to begin multiplying abnormally. Most of these changes are not hereditary.
Less commonly, some pituitary adenomas may be associated with hereditary genetic syndromes, such as multiple endocrine neoplasia type 1. However, these cases represent a minority.
The most important thing is to have an accurate diagnosis and individualized follow-up, since the course of the disease depends on the size of the adenoma, its hormonal behavior, and the symptoms it causes.
Diagnosis and Medical Tests
The diagnosis of a pituitary adenoma is based on symptoms, a physical examination, hormone tests, and imaging studies.
In general, the process includes:
- Medical history and physical examination: Symptoms, possible hormonal changes, personal and family history, as well as signs related to visual or endocrine abnormalities are assessed.
- Blood and urine tests: These allow for the measurement of various hormones and determine whether the pituitary gland is producing too much or too little of any of them.
- Magnetic resonance imaging (MRI): This is the gold standard test for visualizing the pituitary gland, determining the size of the adenoma, and assessing its relationship to nearby structures.
- Ophthalmological examination and visual field testing: This is especially important when a macroadenoma is present or there are visual symptoms, as it helps detect possible abnormalities caused by compression of the optic pathways.
In some cases, the adenoma is identified before it causes symptoms. In other cases, evaluation begins after detecting hormonal abnormalities or visual changes that require a more comprehensive assessment.
Treatments for Pituitary Tumors
Treatment for a pituitary adenoma is determined on an individual basis. Not all tumors require the same approach: some only need periodic monitoring, while others can be treated with medication, surgery, or radiosurgery.
The choice depends, among other factors, on the size of the adenoma, whether it produces hormones, the presence of symptoms, its growth, and its relationship to the optic nerves.
Medications and Watchful Waiting
For small adenomas that are not growing or causing significant symptoms, a watchful-waiting strategy may be considered, involving periodic clinical follow-ups, hormone tests, and MRI scans.
Medications can also be the primary treatment for some types of adenomas. For example, prolactinomas typically respond to drugs that reduce prolactin and help control tumor growth.
In other functioning adenomas, medications may be used to reduce excess hormone production before or after surgery, or when other alternatives are not appropriate.
Transsphenoidal Surgery
Transsphenoidal surgery is one of the most commonly used techniques for treating certain pituitary adenomas. It involves accessing the pituitary region through the nose and the sphenoid sinus, without the need for a large opening in the skull.
It may be considered when the tumor causes significant symptoms, affects vision, shows significant growth, or does not respond adequately to drug therapy.
As with any surgical procedure, the indication depends on the characteristics of each individual case and must be evaluated by a team with experience in pituitary disorders.
Radiosurgery
Radiosurgery may be considered in select situations, particularly when part of the tumor remains after surgery, the tumor progresses during follow-up, or further surgery is not feasible.
This technique allows for the highly precise delivery of radiation to the adenoma, while minimizing the dose received by nearby healthy structures. In the case of pituitary adenomas, treatment planning is particularly important due to the proximity of the optic nerves and other sensitive structures.
IRCA is equipped with ZAP-X, a non-invasive stereotactic brain radiosurgery system that allows for highly precise treatment planning and delivery. Its design enables frameless intracranial radiosurgery, with special attention paid to nearby healthy structures.
The indication and number of sessions are determined on a case-by-case basis, with the goal of achieving tumor control while preserving visual and hormonal function as much as possible.
SOURCES
Spanish Society of Endocrinology and Nutrition (SEEN). Guide to Pituitary Tumors for Patients. https://www.seen.es/ModulGEX/workspace/publico/modulos/web/docs/apartados/1942/210121_021832_3674429582.pdf
Orphanet. Pituitary adenoma.
https://www.orpha.net/es/disease/detail/91349
MedlinePlus. Pituitary tumor. https://medlineplus.gov/spanish/ency/article/000704.htm
MSD Manual, Professional Version. Pituitary tumors. https://www.msdmanuals.com/es/professional/trastornos-neurol%C3%B3gicos/tumores-intracraneanos-y-espinales/tumores-hipofisarios
Learn Skull Base. Pituitary adenoma. https://aprenderbasedecraneo.com/enfermedades/adenoma-hipofisario/
IRCA Radiosurgery. ZAP-X. https://www.irca-radiocirugia.com/en/zap-x/
IRCA Radiosurgery. Pituitary Macroadenoma. https://www.irca-radiocirugia.com/en/success-cases/pituitary-macroadenoma/