SLOT: Full Definition
What is a pituitary adenoma?
A pituitary adenoma — also called a pituitary tumor or, when it secretes prolactin, a prolactinoma — is a noncancerous growth of the pituitary gland, the small structure at the base of the brain that orchestrates the body's endocrine system. Although adenomas are almost always benign, they can cause significant hormone imbalances by either over-producing a particular pituitary hormone or by pressing on surrounding tissue and reducing other hormones.
Pituitary adenomas are surprisingly common. Many are small, asymptomatic, and discovered incidentally on brain imaging. Others produce a recognizable hormonal pattern that finally explains symptoms a woman has lived with for years.
What causes pituitary adenomas?
Most pituitary adenomas arise spontaneously, without an identifiable cause. A small proportion are linked to genetic syndromes such as Multiple Endocrine Neoplasia type 1 (MEN1). They are categorized by what they secrete:
- Prolactinomas — the most common type, causing Hyperprolactinemia
- Growth hormone-secreting tumors, causing Acromegaly
- ACTH-secreting tumors, causing Cushings Syndrome
- TSH-secreting tumors, causing central hyperthyroidism (rare)
- Non-functioning adenomas, which don't secrete excess hormone but can still cause Hypopituitarism by compression
How is a pituitary adenoma diagnosed?
Diagnosis combines hormone testing and imaging. Depending on symptoms, your clinician may order prolactin, IGF-1, morning cortisol or a dexamethasone suppression test, TSH and Free T4, LH, FSH, and estradiol or testosterone. MRI of the pituitary with contrast is the imaging study of choice and can detect tumors as small as a few millimeters. Visual field testing is added when a larger tumor may be pressing on the optic chiasm, which can affect peripheral vision.
How is a pituitary adenoma treated?
Treatment depends on the type, size, and symptoms. Prolactinomas typically respond well to dopamine agonist medications such as cabergoline. Growth hormone- and ACTH-secreting tumors are often treated surgically by a specialized neurosurgeon, sometimes followed by medication or radiation. Small, non-functioning, asymptomatic adenomas may simply be monitored with periodic MRI and labs.
Pituitary adenomas are not treated at Modern Thyroid Clinic — they require a neurosurgeon and endocrinologist team. However, MTC frequently helps identify these tumors when patients present with stubborn thyroid, fertility, or menstrual symptoms, and we coordinate ongoing hormone replacement and root-cause care alongside specialty management.
Common symptoms
Common questions
Are pituitary adenomas cancerous?
The overwhelming majority of pituitary adenomas are benign — meaning they don't spread to other parts of the body. True pituitary cancer (pituitary carcinoma) is extremely rare. That said, even a benign adenoma can cause real problems by over-secreting hormones or by compressing nearby structures, so finding one usually leads to a careful workup and follow-up plan with an endocrinologist and, if needed, a neurosurgeon.
Do pituitary tumors always require surgery?
No. Many pituitary adenomas are managed without surgery. Prolactinomas in particular usually shrink and become hormonally inactive on dopamine agonist medication. Small, non-secreting tumors that aren't causing symptoms are often simply monitored with periodic imaging. Surgery is generally reserved for tumors causing visual symptoms, hormonal excess that doesn't respond to medication, or growth on follow-up scans.
How would I know if I had one?
Symptoms depend on the type. Common clues include unexplained changes in periods, infertility, milky nipple discharge, persistent headaches, peripheral vision changes, unexpected weight changes, or features of [cushings-syndrome] or [acromegaly]. Because these symptoms overlap with many other hormone conditions, a careful history and a tailored hormone panel — like the workup done at Modern Thyroid Clinic — is what surfaces these tumors when they're present.
Think you might be dealing with this?
Talk to a Modern Thyroid Clinic specialist about your symptoms, labs, and next steps.
Book a Discovery CallThis content is for educational purposes only and is not medical advice. Consult a licensed clinician for diagnosis and treatment. Content on this page does not create a doctor-patient relationship with Modern Thyroid Clinic.