What are the symptoms of a pituitary macroadenoma in adults?

Pituitary Macroadenoma Symptoms

Pituitary macroadenomas cause symptoms through two primary mechanisms: mass effect on surrounding structures (headaches, visual field defects, cranial nerve palsies) and hormonal dysfunction (either hypersecretion or hypopituitarism), with visual impairment, headache, and hypogonadism being the most common presenting features. 1, 2

Mass Effect Symptoms

Visual disturbances are the hallmark presentation of macroadenomas and represent an urgent indication for intervention when sight is threatened:

• Visual field defects occur in 18-78% of patients with macroadenomas, classically presenting as bitemporal hemianopsia due to optic chiasm compression 2, 3
• Visual acuity impairment requires early formal assessment including visual fields and fundoscopy 1, 4
• Cranial nerve palsies, particularly oculomotor nerve dysfunction, can occur with large tumors extending laterally into the cavernous sinus 5

Headaches are present in 17-75% of patients with macroadenomas and result from dural stretch and mass effect 2

Raised intracranial pressure can occur in severe cases with very large tumors 5

Pituitary apoplexy (acute hemorrhage or infarction) presents with sudden severe headache, visual loss, and altered consciousness—this complication may be more common in younger patients than adults 1

Hormonal Dysfunction Symptoms

Hypopituitarism (Most Common in Non-Functioning Macroadenomas)

Hypopituitarism occurs in 34-89% of patients with macroadenomas and manifests through deficiency of one or multiple pituitary hormones 1, 2:

• Hypogonadism: Secondary amenorrhea in women; decreased libido and erectile dysfunction in men 1, 6
• Hypothyroidism: Fatigue, weight gain, cold intolerance 1
• Hypocortisolemia: Fatigue, weakness, hypotension, features of adrenal insufficiency 1, 7
• Growth hormone deficiency: Growth failure in children and adolescents 1
• Mild hyperprolactinemia: Can occur due to "stalk effect" (compression of pituitary stalk interrupting dopamine inhibition) 1

Important caveat: Central diabetes insipidus (arginine vasopressin deficiency) is extremely rare at initial presentation of a macroadenoma unless apoplexy has occurred—its presence strongly suggests an alternative diagnosis such as craniopharyngioma, histiocytosis, or germ-cell tumor 1

Hormone Hypersecretion (Functioning Adenomas)

Prolactin excess (prolactinomas account for 53% of all pituitary adenomas):

• Women: Amenorrhea, galactorrhea, infertility 6, 2, 8
• Men: Decreased libido, erectile dysfunction, infertility, rarely gynecomastia 6, 8

Growth hormone excess (12% of adenomas):

• Adults: Acromegaly with enlargement of hands, feet, lips, tongue, nose 8
• Children: Gigantism 2

ACTH excess (4% of adenomas):

• Cushing disease: Central obesity, hypertension, diabetes, purple striae, moon facies, buffalo hump 8

TSH excess (1% of adenomas):

• Hyperthyroidism: Weight loss, tremor, palpitations, heat intolerance 5, 8

Rare Psychiatric Presentations

Psychosis and schizophrenia-like symptoms have been rarely reported with pituitary macroadenomas, particularly prolactinomas, though the mechanism remains unclear 7. These include:

• Visual and olfactory hallucinations
• Delusions
• Apathy and personality changes
• Episodes of confusion 7

Clinical Pearls

• Non-functioning adenomas (30% of all pituitary adenomas) present exclusively with mass effect symptoms, as they do not produce hormones 2
• Microadenomas (<10 mm) are typically asymptomatic and discovered incidentally, whereas symptomatic presentations indicate macroadenomas (≥10 mm) 1, 2
• The triad of headache, visual impairment, and hypogonadism represents the most common presenting constellation in surgical series 1