The exact cause of pituitary tumors is unknown.
In rare cases, inherited disorders may cause pituitary tumors. These diseases include multiple endocrine neoplasia type 1 (MEN 1) syndrome, Carney complex, and isolated familial acromegaly.1
For more information about these conditions, read the section Are there disorders associated with pituitary tumors?
It is likely that pituitary tumors are caused by abnormalities in one or more genes, by hormonal abnormalities, or by a combination of these factors.2 Scientists, including NICHD researchers, are still working to figure out what causes pituitary tumors.