MRI is the primary imaging modality and can detect microadenomas as small as two to three millimeters. A comprehensive endocrine evaluation is performed in all patients and includes baseline serum measurement of prolactin, IGF-1 (a surrogate for growth hormone excess), cortisol and ACTH (with dynamic testing such as late-night salivary cortisol and low-dose dexamethasone suppression for Cushing's assessment), TSH, free T4, and gonadotropins.
Treatment is highly tumor-specific. Prolactinoma is uniquely managed with dopamine agonist medications as first-line therapy. These drugs normalize prolactin levels, restore gonadal function, and reduce tumor size in the majority of patients, making surgery unnecessary in most cases. For all other functioning adenomas and for non-functioning macroadenomas causing mass effects, transsphenoidal surgery — most commonly performed via an endoscopic endonasal (through-the-nose) approach — is the treatment of first choice. Surgical outcomes are best for microadenomas treated at high-volume centers, with cure rates declining for larger tumors and those with cavernous sinus invasion.
For tumors that cannot be completely removed, persist, or recur following surgery, Gamma Knife provides effective tumor control with gradual hormonal normalization over months to years. Patients who develop hypopituitarism require lifelong hormonal replacement therapy, and cortisol replacement in particular must be maintained with great care, especially during illness or surgery. All patients require long-term endocrine follow-up.