What is the inpatient endocrine workup for a suprasellar (located above the sella turcica) mass?

Inpatient Endocrine Workup for Suprasellar Mass

The comprehensive inpatient endocrine workup for a suprasellar mass should include morning pituitary hormone testing (TSH, free T4, ACTH, cortisol, gonadal hormones), followed by high-resolution MRI of the sella with contrast as the primary imaging modality. 1

Initial Hormonal Evaluation

Baseline Pituitary Function Assessment

• Morning hormone panel (preferably around 8 AM):
  • Thyroid function: TSH and free T4 (to assess for central hypothyroidism) 1
  • Adrenal function: ACTH and cortisol (to assess for central adrenal insufficiency) 1
  • Gonadal function:
    • Males: Testosterone, FSH, LH
    • Females: Estradiol, FSH, LH 1
  • Growth hormone axis: IGF-1 (as a surrogate for GH function)
  • Prolactin: To assess for hyperprolactinemia (which may be from the mass itself or from stalk effect)

Additional Endocrine Testing

• 1 mcg cosyntropin stimulation test: If morning cortisol is borderline or if there is high clinical suspicion for adrenal insufficiency 1
• Glucose monitoring: Fasting glucose and HbA1c to assess for diabetes insipidus or other glycemic abnormalities 1
• Water deprivation test: If diabetes insipidus is suspected based on polyuria and hypernatremia

Imaging Studies

Primary Imaging

• MRI sella with high-resolution pituitary protocol: The preferred diagnostic imaging modality 1
  • Should include both pre-contrast and post-contrast sequences
  • Thin-section, focused field-of-view sequences targeted for sellar and parasellar assessment
  • Allows characterization of the mass and its relationship to surrounding structures (optic chiasm, cavernous sinus, etc.)

Complementary Imaging

• CT sella: May provide complementary information about bony anatomy and calcifications 1
  • Particularly useful for surgical planning
  • Less sensitive than MRI for soft tissue characterization

Clinical Considerations

Urgent Assessment for Adrenal Insufficiency

• Central adrenal insufficiency is a potentially life-threatening complication of suprasellar masses
• If suspected, initiate stress-dose glucocorticoids before confirmatory testing is complete
• Monitor for signs of adrenal crisis: hypotension, hyponatremia, hyperkalemia, hypoglycemia 1, 2

Visual Field Assessment

• Formal visual field testing should be performed due to the proximity of the optic chiasm
• Document any visual deficits as baseline before treatment

Management Considerations

Perioperative Hormone Replacement

• Glucocorticoid replacement: Required in all patients with evidence of adrenal insufficiency 2
  • Hydrocortisone 2 mg/kg at induction
  • Continue IV hydrocortisone until oral intake is resumed
• Thyroid hormone replacement: For patients with central hypothyroidism
  • Only start after adequate glucocorticoid coverage to avoid precipitating adrenal crisis 1

Common Pitfalls to Avoid

• Failure to diagnose adrenal insufficiency: Can lead to life-threatening adrenal crisis during surgery or other stressful events
• Premature thyroid hormone replacement: Starting levothyroxine before glucocorticoid replacement in patients with both deficiencies can precipitate adrenal crisis
• Misdiagnosis of reversible causes: Some suprasellar masses (like those secondary to primary hypothyroidism) may resolve with appropriate hormone replacement 3
• Missing late endocrine complications: Even after successful treatment of the mass, patients may develop delayed endocrine abnormalities requiring long-term follow-up 4

Differential Diagnosis Considerations

Different suprasellar masses have distinct endocrine profiles that can help guide diagnosis:

• Pituitary adenoma with suprasellar extension: Often presents with specific hormone excess or deficiency
• Craniopharyngioma: Typically presents with multiple anterior pituitary hormone deficiencies
• Rathke's cleft cyst: May cause variable hormone deficiencies
• Meningioma: Often presents with gradual onset of hypopituitarism
• Hypothalamic glioma: May present with diabetes insipidus and growth failure 5

The endocrine workup, combined with imaging characteristics, helps differentiate between these entities and guides appropriate management.