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Pituitary Adenoma
Aka: Pituitary Adenoma, Pituitary Neoplasm, Functionless Pituitary Adenoma, Non-Functioning Pituitary Adenoma, Secretory Pituitary Adenoma, Pituitary Macroadenoma, Pituitary Microadenoma, Pituitary Incidentaloma, Prolactinoma, Prolactin-Secreting Pituitary Adenoma, Growth Hormone-Secreting Pituitary Adenoma, ACTH-Secreting Pituitary Adenoma, Thyrotroph Adenoma, TSH-Secreting Adenoma, Pituiatry Apoplexy, Pituitary Lesion
- See Also
- Pituitary Gland
- Hyperprolactinemia
- Galactorrhea
- Incidentaloma
- Pathophysiology
- See Pituitary Gland
- Definition: Pituitary Adenoma
- Benign Pituitary Neoplasm
- Epidemiology
- Pituitary Adenomas account for 10-15% of all Intracranial Masses
- Prevalence: 77 per 100,000 persons
- Prevalence suspected to be much higher (May incidentally occur in as many as 20% of all patients)
- Types: Based on Hormone Secretion
- Prolactinoma (>40% of adenomas)
- Lactotroph cell adenoma with Hyperprolactinemia
- Presents with Galactorrhea and Gynecomastia
- Also suppresses LH secretion resulting in Erectile Dysfunction in men and Amenorrhea and Infertility in women
- Non-functioning Adenoma (>28% of adenomas)
- Findings are related to mass effect (Headache, Vision change) or Hypopituitarism
- Growth HormoneSecreting adenomas (11-13% of adenomas)
- Somatotroph cell adenoma with Gigantism (prior to Growth Plate closure) or Acromegaly (adults)
- Presents with hand/foot/Mandible hypertrophy, Fatigue, proximal Muscle Weakness, Hypertension, Cardiomegaly or LVH
- ACTH Secreting adenomas (1-2%)
- Corticotroph cell adenoma with increased ACTH and Cushing Disease
- Presents with proximal Muscle Weakness, striae, central Obesity, moon facies, Hypertension, Acne Vulgaris, Hyperglycemia
- TSH-Secreting Adenoma (rare)
- Thyrotroph cell adenoma with increased TSH and Hyperthyroidism
- LH or FSH Secreting tumor (rare)
- Gonadotroph cell adenoma typically results in no symptoms unless mass effect (Headache, Vision change) or Hypopituitarism
- However Prolactinomas do suppress LH secretion resulting in Hypogonadism
- Types: Based on size
- Microadenoma (<10 mm)
- Macroadenoma (10 mm or larger)
- Most likely to grow and manifest clinically
- Findings: Presentations
- Incidental finding on imaging (asymptomatic Pituitary Incidentaloma)
- Found in >10% of patients and Clinically Significant in 0.1% of patients
- Hormone increased secretion - typically only one of the following affected (see above)
- Prolactinoma (Hyperprolactinemia)
- Gigantism in children prior to Growth Plate fusion or Acromegaly in adults (increased Growth Hormone)
- Cushing Disease (increased ACTH)
- Central Hyperthyroidism (increased TSH, rare)
- Mass effect (delayed presentation, especially in non-functioning adenomas)
- Hypopituitarism (30% of Pituitary Adenomas)
- Headache
- Related to dural sheath Stretching
- Not correlated with Pituitary Adenoma size
- Vision change
- Initial compression
- Optic Chiasm compression from superior aspect
- Results in bitemporal hemianopsia
- Later may expand into the Cavernous Sinus laterally with additional Cranial Nerve Involvement (as adenoma grows)
- Cranial Nerve III (Oculomotor Nerve)
- Cranial Nerve IV (Trochlear Nerve)
- Cranial Nerve VI (Abducens Nerve)
- Later expansion
- Cranial Nerve II (Optic Nerve)
- Labs: Initial
- Serum Prolactin
- Serum Prolactin 100-200 mcg/L is typical for most Prolactin-Secreting Pituitary Microadenomas
- Serum Prolactin >250 mcg/L is highly suggestive of Prolactinoma
- Serum Prolactin >500 mcg/L is highly suggestive of macroprolactinoma (Test Specificity 98%, but poorly sensitive)
- Very large macroadenomas (>3 cm) may give false negative Serum Prolactin (Hook effect)
- False Negatives (Hook effect) result if Prolactin detecting Antibody is saturated by very high Prolactin levels
- Insulin-like growth factor 1 (IGF-1)
- Leutenizing Hormone (LH)
- Follicle Stiulating Hormone (FSH)
- Thyroid Stimulating Hormone (TSH)
- Thyroxine Level (T4 Free)
- 24 hour Urine Cortisol (or late night Salivary Cortisol or low dose Dexamethasone suppression)
- Imaging
- Brain MRI (with and without gadolinium, cone-down sella turcica) - preferred
- Test Sensitivity: 61-72% (for sella turcica mass)
- Test Specificity: 88-90% (for sella turcica mass)
- Also obtain if MRI not contraindicated and Pituitary Adenoma inicidentally found on CT Head
- Repeat Brain MRI in 6-12 months depending on lesion size
- CT Head
- Indicated if MRI contraindicated or not available
- Coronal sections of 1.5 mm or less
- Differential Diagnosis: Incidentaloma
- Pituitary Adenoma
- Rathke Cleft Cyst
- Craniopharyngioma
- Pituitary Hyperplasia
- Evaluation: Approach
- Obtain all initial labs as above
- Even if asymptomatic and pituitary mass incidentally found on brain imaging
- Obtain Brain imaging (MRI preferred)
- If Pituitary Adenoma is suspected
- Ophthalmology and Endocrine referrals as below
- Suspected Pituitary Adenoma
- Consult ophthalmology for macroadenoma even if no visual changes are readily evident
- Detailed Visual Field testing
- Detailed Eye Examination
- Management
- Management directed by endocrinology
- Consult prior to starting management and in completing evaluation once Pituitary Adenoma is identified
- Prolactinoma
- Refer to endocrinology
- Titrate dosing to decrease tumor size, Prolactin level and improve gonadal function
- Consider no treatment in asymptomatic microadenomas (e.g. normal Menses)
- Dopamine Agonists (adult dosing)
- Cabergoline
- Preferred agent due to association with more rapid improvement and better tolerated by patients
- Dosing: 0.25 orally twice weekly and increase in 0.25 mg increments/month to a maximum of 1 mg twice weekly
- Bromocriptine (Parlodel)
- Preferred in pregnancy or desired fertility (due to longer established safety record)
- Dosing: 1.25 to 2.5 mg at bedtime and increase by 2.5 mg every 2-7 days typically to 2.5 to 15 mg daily (absolute max 40 mg)
- Miscellaneous medications
- Oral Contraceptives may be considered for Amenorrhea management
- ACTH-Secreting Pituitary Adenoma
- Refer to endocrinology and neurosurgery
- Surgical management options
- Surgical Resection
- Radiation Therapy
- Bilateral adrenalectomy
- Adrenostatic Medications (decrease adrenal steroidogenesis)
- Titrate medication dosing to decrease tumor size, Cortisol level and improve pituitary function
- Metyrapone (Metopirone) 250 mg four times daily (up to 6000 mg/day maximum)
- Mefepristone (Mifeprex) 300 mg once daily (up to 1200 mg/day maximum)
- Mitotane (Lysodren) 500 mg three times daily (up to 9000 mg/day maximum)
- Ketoconazole
- No longer recommended due to Ketoconazole hepatotoxicity
- GH-Secreting Pituitary Adenoma
- Refer to endocrinology and neurosurgery
- Surgical management options
- Surgical Resection
- Radiation Therapy
- Somatostatin Analogues
- Titrate medication dosing to decrease tumor size, Growth Hormone and IGF-1 level and improve pituitary function
- Octreotide (Sandostatin) 50 mcg SQ three times daily (or depot 20 mg every 4 weeks)
- Lanreotide (Somatuline) 90 mg SQ every 4 weeks
- Growth Hormone antagonists (reduce IGF-1 and associated Acromegaly symptoms)
- Pegvisomant (Somavert) 15-20 mg daily
- Non-Functioning Pituitary Adenoma
- Obtain ophthalmology Consultation for Visual Field testing and complete Eye Examination
- Indicated for Non-functioning Pituitary Macroadenoma (>1 cm)
- Neurosurgery Consultation indications
- Abnormal ophthalmology examination (especially Visual Field deficit)
- Neurologic symptoms (e.g. Headache)
- Lesion increasing in size to abut the Optic Chiasm or growth to >1 cm (macroadenoma)
- Repeat MRI Brain in one year, then in 2-3 years
- Neurosurgery Consultation if meets criteroa
- Repeat labs (see above), then in 1-3 years (or as directed by endocrinology)
- If abnormal, treat as functioning adenoma as above
- Complications: Pituitary Apoplexy
- Bleeding and swelling at Pituitary Adenoma
- Presents with Thunderclap Headache, Visual Field cut (bitemporal hemianopsia) and cranial Neuropathy
- Lumbar Puncture with high opening pressure and CSF Red Blood Cells
- CT Head is often normal
- References
- Freda (2011) J Clin Endocrinol Metab 96(4): 894-904 [PubMed]
- Hitzeman (2014) Am Fam Physician 90(11): 784-9 [PubMed]
- Lake (2013) Am Fam Physician 88(5): 319-27 [PubMed]
- Molitch (2001) Endocrinol Metab Clin North Am 30:585 [PubMed]
- Schlechte (2003) N Engl J Med 349:2035-41 [PubMed]