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Pituitary Adenoma

Pituitary Adenoma is a topic covered in the 5-Minute Clinical Consult.

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Typically benign, slow-growing tumors that arise from cells in the pituitary gland

  • Pituitary adenomas have been identified as the third most frequent intracranial tumor; accounts for 10–25%
  • Subtypes (hormonal): prolactinoma (PRL) 25–40%, nonfunctioning pituitary adenomas 30%, somatotroph adenoma (growth hormone [GH]) 15–20%, corticotroph adenoma (adrenocorticotropic hormone [ACTH]) 5–10%, thyrotroph adenoma (thyroid-stimulating hormone [TSH]) <1%, gonadotropinoma (luteinizing hormone/follicle-stimulating hormone [LH/FSH]), mixed (1)[A]
  • Defined as microadenoma <10 mm and macroadenoma ≥10 mm
  • May secrete hormones and/or cause mass effects


  • Predominant age: Age increases incidence.
  • Predominant sex: female > male (3:2) for microadenomas (often delayed diagnosis in men)

  • Autopsy studies have found microadenomas in 3–27% and macroadenomas in <0.5% of people without any pituitary disorders.
  • MRI scans illustrate abnormalities consistent with pituitary adenoma in 1/10 persons.
  • Clinically apparent pituitary tumors are seen in 18/100,000 persons.

Etiology and Pathophysiology

  • Monoclonal adenohypophysial cell growth
  • Hormonal effects of functional microadenomas often prompt diagnosis before mass effect.
  • PRL increased by functional prolactinomas or inhibited dopaminergic suppression by stalk effect

  • Carney complex
  • Familial isolated pituitary adenomas: ~15% have mutations in the aryl hydrocarbon receptor–interacting protein gene (AIP); present at a younger age and are larger in size (2)
  • McCune-Albright syndrome
  • Multiple endocrine neoplasia type 1 (MEN1)-like phenotype (MEN4): germline mutation in the cyclin-dependent kinase inhibitor 1B (CDKN1B) (2)

Risk Factors

Multiple endocrine neoplasias

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Stephens, Mark B., et al., editors. "Pituitary Adenoma." 5-Minute Clinical Consult, 27th ed., Wolters Kluwer, 2019. Medicine Central, im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116457/all/Pituitary_Adenoma.
Pituitary Adenoma. In: Stephens MB, Golding J, Baldor RA, et al, eds. 5-Minute Clinical Consult. 27th ed. Wolters Kluwer; 2019. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116457/all/Pituitary_Adenoma. Accessed June 19, 2019.
Pituitary Adenoma. (2019). In Stephens, M. B., Golding, J., Baldor, R. A., & Domino, F. J. (Eds.), 5-Minute Clinical Consult. Available from https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116457/all/Pituitary_Adenoma
Pituitary Adenoma [Internet]. In: Stephens MB, Golding J, Baldor RA, Domino FJ, editors. 5-Minute Clinical Consult. Wolters Kluwer; 2019. [cited 2019 June 19]. Available from: https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116457/all/Pituitary_Adenoma.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC T1 - Pituitary Adenoma ID - 116457 ED - Stephens,Mark B, ED - Golding,Jeremy, ED - Baldor,Robert A, ED - Domino,Frank J, BT - 5-Minute Clinical Consult, Updating UR - https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116457/all/Pituitary_Adenoma PB - Wolters Kluwer ET - 27 DB - Medicine Central DP - Unbound Medicine ER -