Pituitary adenoma

A pituitary adenoma is a growth arising from the cells of the pituitary gland, a pea-sized gland that sits in a hollow of bone at the base of the skull, just below the brain and the crossing of the optic nerves. The pituitary controls other hormone glands, including the thyroid and adrenal glands1. Most pituitary adenomas are not cancerous1.

An adenoma can cause problems in three ways2:

• Too much of a hormone. A functioning adenoma produces excess prolactin, growth hormone, ACTH or, rarely, TSH, each causing its own syndrome.
• Too little of other hormones. A larger adenoma can reduce the gland's normal output, a condition called hypopituitarism.
• Pressure on nearby structures, especially the optic nerves, which can cause headache and loss of vision.

Types

Pituitary adenomas are described in three ways at once34:

• By hormone activity: clinically functioning (prolactinoma, growth hormone-secreting, ACTH-secreting, TSH-secreting) or nonfunctioning.
• By size: a microadenoma is under 10 mm and a macroadenoma 10 mm or more.
• By how it was found: an incidentaloma is one discovered on a scan done for another reason.

The 2022 World Health Organization classification also uses the term pituitary neuroendocrine tumor (PitNET). The name reflects the cells the tumor comes from; it doesn't mean the tumor behaves like a spreading cancer4. The types and hormones page explains each type.

Diagnosis

Diagnosis combines three kinds of test3:

• blood tests for both excess and deficient hormones
• MRI of the pituitary, which shows the size of the adenoma and its relation to the optic nerves and surrounding structures
• an eye examination with visual field testing, when the adenoma is near the optic nerves

See symptoms and diagnosis.

Treatment

Treatment depends on the type:

• Nonfunctioning adenomas without effects on vision or hormones can often be watched with planned scans. Surgery is considered for vision problems, growth or other concerns3.
• Prolactinomas are usually treated with dopamine agonist medicines, which control many of them. Expert surgery is now also discussed as a first option for selected small or well-defined tumors5.
• ACTH-secreting adenomas (Cushing disease) are usually treated first with surgery by an experienced pituitary surgeon6.
• Growth hormone-secreting adenomas (acromegaly) are commonly treated first with surgery, with medicines when the disease persists7.

Most operations are done through the nose, by the transsphenoidal route, without an opening in the skull8. Radiation and hormone replacement have their own roles. See treatment options and surgery and follow-up.

Pituitary apoplexy: an emergency

A sudden, severe headache, especially with new loss of vision, double vision or drowsiness, needs emergency care. It can be pituitary apoplexy, bleeding into or sudden loss of blood supply to a pituitary tumor9. Call your local emergency number.

About the editor

Dr. Kamran Aghayev

Neurosurgeon, Associate Professor of Neurosurgery · Istanbul

Dr. Kamran Aghayev is a neurosurgeon in Istanbul and an associate professor of neurosurgery, with more than 20 years in practice. He trained in neurosurgery at Hacettepe University in Ankara, completed spinal oncology and neuro-oncology fellowships at the H. Lee Moffitt Cancer Center in Tampa, Florida, and taught there as a clinical instructor before returning to Turkey. He chaired the neurosurgery department at Biruni University in Istanbul from 2017 to 2020. His published work includes a surgical technique for jugular vein decompression in atlanto-styloid compression and the PURED operation for thoracic outlet syndrome, and he is a named inventor on 13 U.S. patents for spinal devices.

How this site is editedkamranaghayev.com

References

1. National Cancer Institute. What Are Pituitary Tumors? Updated 28 March 2025. Source ↩
2. National Cancer Institute. Pituitary Tumors Signs & Symptoms. Updated 28 March 2025. Source ↩
3. Fleseriu M et al. Nat Rev Endocrinol. 2025;21:638–655. Published 24 June 2025. doi:10.1038/s41574-025-01134-8. Source ↩
4. Ho KKY et al. Nat Rev Endocrinol. 2023. Published 17 August 2023. doi:10.1038/s41574-023-00883-8. Source ↩
5. Petersenn S et al. Nat Rev Endocrinol. 2023;19:722–740. doi:10.1038/s41574-023-00886-5. Read with Author Correction, 17 October 2023. Source ↩
6. Fleseriu M et al. Lancet Diabetes Endocrinol. 2021;9:847–875. doi:10.1016/S2213-8587(21)00235-7. Source ↩
7. Melmed S et al. Nat Rev Endocrinol. 2025;21:718–737. doi:10.1038/s41574-025-01148-2. Source ↩
8. National Cancer Institute. Pituitary Tumors Treatment. Updated 28 March 2025. Source ↩
9. Baldeweg SE et al. Society for Endocrinology Endocrine Emergency Guidance. Endocr Connect. 2016;5:G12–G15. doi:10.1530/EC-16-0057. Source ↩

Related pages

• Types and hormonesSeparate a size label from hormone activity, pathological subtype and the way a lesion was discovered.
• Symptoms and diagnosisHow endocrine, imaging and vision findings fit together without turning a symptom list or scan into a diagnosis.
• Treatment optionsObservation, endocrine medicines, surgery and radiation have different roles depending on the lesion and the goal of care.
• Surgery and follow-upUnderstand the purpose of surgery, the different meanings of an outcome and the need for continuing endocrine and imaging care.