Inpatient Workup for Pituitary Macroadenoma
The comprehensive inpatient workup for a pituitary macroadenoma should include complete pituitary function testing, detailed visual assessment, and high-quality MRI imaging of the sella with pituitary cuts, with urgent surgical intervention indicated for progressive visual deterioration or signs of pituitary apoplexy. 1
Initial Evaluation Components
Hormonal Assessment
- Complete baseline pituitary function testing:
- Thyroid function (TSH, free T4)
- Adrenal function (morning cortisol, ACTH)
- Gonadal function (LH, FSH, testosterone/estradiol)
- Prolactin levels (to rule out prolactinoma or stalk effect)
- Growth hormone axis (IGF-1)
- Glucose levels and HbA1c 1
- Specific hormone hypersecretion screening:
- 1 mg dexamethasone suppression test for autonomous cortisol secretion
- Aldosterone-to-renin ratio if hypertension/hypokalemia present
- Plasma or 24-hour urinary metanephrines if symptoms of catecholamine excess
- Serum androgen testing if signs of virilization 1
Imaging Studies
- MRI of the sella with pituitary cuts (gold standard) to evaluate:
- Tumor size and extension
- Compression of optic chiasm
- Cavernous sinus invasion
- Stalk compression 1
- Consider non-contrast CT as complementary imaging if needed to distinguish density characteristics 2
Visual Assessment
- Complete visual evaluation including:
- Visual acuity
- Visual fields (Goldmann perimetry preferred)
- Fundoscopy
- Color evaluation (optional)
- Optical coherence tomography (OCT) for baseline retinal nerve fiber layer assessment 1
Management Decision Algorithm
Immediate Surgical Indications
- Progressive visual deterioration
- Acute visual threat
- Signs of pituitary apoplexy (sudden headache, visual loss, ophthalmoplegia)
- Significant mass effect with neurological symptoms 1
Other Indications for Surgical Intervention
- Visual pathway compression
- Symptomatic hypopituitarism
- Documented tumor growth on MRI
- Headache attributable to the tumor 1
Medical Management
- Initiate hormone replacement therapy for documented deficiencies:
- Cortisol replacement (hydrocortisone)
- Thyroid hormone replacement (levothyroxine)
- Sex hormone replacement
- Growth hormone replacement if indicated 1
- For prolactinomas: dopamine agonists (cabergoline or bromocriptine) are first-line treatment, even for macroadenomas with chiasmatic compression 3, 4
- Non-functioning adenomas generally do not respond to medical therapy 1
Post-Diagnostic Surveillance
Post-Operative MRI Surveillance
- MRI at 3 months to assess residual tumor
- Follow-up MRI at 6 months, then at 1,2,3, and 5 years 1
- Monitor for development or worsening of hypopituitarism 1
For Incidental Macroadenomas (if not operated)
- Initial MRI at 6 months
- Annual MRI for 3 years
- Gradual reduction in frequency thereafter
- Lifelong clinical surveillance 1
Special Considerations
Diagnostic Pitfalls
- Mild hyperprolactinemia may be due to stalk compression rather than a prolactin-secreting tumor
- Central diabetes insipidus at diagnosis is extremely rare in pituitary adenomas and suggests alternative diagnoses (craniopharyngioma, Rathke's cleft cyst, germ cell tumors) 1
- Physiological pubertal pituitary hypertrophy can mimic adenoma growth in younger patients 2, 1
Treatment Considerations
- Residual tumor visible on post-operative MRI increases recurrence risk (up to 38% within 5 years) 2, 1
- Consider radiotherapy for residual or recurrent tumor 1
- For recurrent non-functioning adenomas, consider second surgery or radiotherapy 2
- Temozolomide may be considered for aggressive pituitary adenomas refractory to standard treatments 5
Follow-up Recommendations
- Macroadenomas require more vigilant monitoring than microadenomas due to higher growth rates 2, 1
- Visual surveillance should be adjusted to individual needs for operated or incidental macroadenomas 2
- Consider using non-contrast MRI sequences during follow-up to avoid gadolinium accumulation 1
By following this structured approach to the inpatient workup of pituitary macroadenomas, clinicians can ensure comprehensive evaluation and appropriate management decisions to optimize patient outcomes related to morbidity, mortality, and quality of life.