About This Page
This is a clinician-written, evidence-based summary aligned to the USMLE Step 2 CK Content Outline. It is intended for medical students preparing for USMLE Step 2 CK. Management reflects current ACC/AHA, USPSTF, and APA guidelines. Always cross-reference with UpToDate, institutional protocols, and clinical judgment.
The Bottom Line
- Macroadenoma mass effect: headache and bitemporal hemianopsia from optic chiasm compression
- Prolactinoma: galactorrhea, amenorrhea/infertility, low libido; first-line treatment is dopamine agonist
- Acromegaly: elevated IGF-1, confirm with failure of GH suppression after oral glucose
- Cushing disease: ACTH-secreting pituitary adenoma causing ACTH-dependent Cushing syndrome
- Pituitary apoplexy = sudden headache, visual loss, ophthalmoplegia, adrenal crisis — emergency steroids and neurosurgical evaluation
Overview
Pituitary adenomas are benign neoplasms of the anterior pituitary that may be nonfunctioning or hormone-secreting. Clinical manifestations arise from hormone excess, hypopituitarism, or mass effect. Prolactinomas are the most common functioning pituitary adenomas. Growth hormone adenomas cause acromegaly in adults. ACTH adenomas cause Cushing disease, the pituitary cause of ACTH-dependent Cushing syndrome.
Epidemiology
Pituitary incidentalomas are increasingly detected on MRI. Microadenomas are <10 mm and macroadenomas are >=10 mm. Prolactinomas are more common in women of reproductive age, while macroprolactinomas are more often diagnosed in men due to delayed symptoms. Acromegaly is rare and often diagnosed years after onset because changes are gradual. Nonfunctioning macroadenomas often present with visual field loss or hypopituitarism.
Clinical Features
Symptoms
Headache, visual difficulty, or bitemporal field loss from macroadenoma
Prolactinoma: galactorrhea, amenorrhea, infertility, erectile dysfunction, low libido
Acromegaly: enlarging hands/feet, increased ring/shoe size, coarse facial features, sweating, arthralgia, carpal tunnel
Cushing disease: weight gain, proximal weakness, purple striae, easy bruising
Pituitary apoplexy: sudden severe headache, vomiting, diplopia, visual loss, collapse
Signs
Bitemporal hemianopsia on visual field testing
Galactorrhea or hypogonadism signs
Acromegaly: frontal bossing, prognathism, macroglossia, widened teeth spacing, large hands
Cushingoid features with proximal myopathy
Hypopituitarism: fatigue, hypotension, secondary hypothyroidism, hypogonadism
Investigations
First-line
Serum prolactinMarkedly elevated in prolactinoma; mild elevations can occur from stalk effect, pregnancy, hypothyroidism, renal failure, or medications
Pituitary hormone panelTSH/free T4, morning cortisol/ACTH, LH/FSH, estradiol/testosterone, IGF-1 when acromegaly suspected
Pituitary MRI with contrastDefines adenoma size, cavernous sinus invasion, optic chiasm compression
Second-line
Visual field testingRequired for macroadenoma near optic chiasm or visual symptoms
IGF-1 and oral glucose suppression testIGF-1 screens for acromegaly; failure of GH suppression after glucose confirms
Cushing screening and ACTH workupLate-night salivary cortisol, dexamethasone suppression, or urinary free cortisol; then ACTH-dependent localization
Specialist
Inferior petrosal sinus samplingFor suspected Cushing disease when pituitary MRI is negative/equivocal or ectopic ACTH remains possible
Neurosurgical evaluationVisual compromise, apoplexy, non-prolactin secreting macroadenoma needing decompression, or failed medical therapy
1
Prolactinoma
- Exclude pregnancy, hypothyroidism, renal failure, and dopamine antagonist medications
- First-line: dopamine agonist, usually cabergoline preferred over bromocriptine because of efficacy and tolerability
- Monitor prolactin and tumor shrinkage; surgery if medication failure/intolerance or acute compression not responding
2
Acromegaly
- Transsphenoidal surgery first-line for most GH-secreting adenomas
- Medical therapy if persistent disease or not surgical candidate: somatostatin analogs, pegvisomant, dopamine agonists in selected patients
- Screen complications: hypertension, diabetes, sleep apnea, cardiomyopathy, colon polyps
3
Cushing disease
- Transsphenoidal resection is first-line
- Medical cortisol-lowering therapy, radiation, or bilateral adrenalectomy in refractory disease
- Provide adrenal replacement as needed after successful surgery while HPA axis recovers
4
Mass effect and hypopituitarism
- Replace deficient hormones, prioritizing glucocorticoids before levothyroxine if central adrenal insufficiency may coexist
- Surgery for visual field defects or optic chiasm compression except many prolactinomas respond to dopamine agonists
5
Pituitary apoplexy
- Immediate stress-dose hydrocortisone
- Urgent MRI, visual assessment, endocrine and neurosurgical evaluation
- Surgical decompression if severe or progressive visual compromise
Complications
- Visual loss: Optic chiasm compression causes bitemporal hemianopsia
- Hypopituitarism: ACTH deficiency can be life-threatening
- Pituitary apoplexy: Hemorrhage/infarction causing sudden headache, ophthalmoplegia, visual loss, and adrenal crisis
- Acromegaly complications: Cardiomyopathy, sleep apnea, diabetes, colon polyps, arthropathy
- Cushing disease complications: Infection, thrombosis, osteoporosis, diabetes, hypertension
USMLE Step 2 CK Exam Tips
- 1Bitemporal hemianopsia = optic chiasm compression from pituitary macroadenoma
- 2Prolactinoma first-line treatment is cabergoline, not surgery, even for many macroadenomas
- 3Mild prolactin elevation can be stalk effect; very high prolactin suggests prolactinoma
- 4Acromegaly diagnosis: elevated IGF-1, confirm with failure of GH suppression after oral glucose
- 5GH causes insulin resistance, so acromegaly patients often have diabetes and hypertension
- 6Cushing disease means pituitary ACTH adenoma; Cushing syndrome is the overall cortisol-excess state
- 7Central hypothyroidism: free T4 is low but TSH may be normal — do not rely on TSH alone
- 8Pituitary apoplexy: give stress-dose hydrocortisone immediately
practicetest your knowledge on pituitary adenoma (prolactinoma, acromegaly, cushing disease)Apply what you've learnt with USMLE Step 2 CK-style questions from the iatroX Q-Bank — endocrine and beyond.
open q-bank