What are the preoperative instructions for a patient with a non-functioning pituitary adenoma (NFPA) planned for surgery?

Preoperative Instructions for Patients with Non-functioning Pituitary Adenomas (NFPA) Planned for Surgery

Routine endocrine evaluation of all anterior pituitary axes and replacement of deficient hormones, particularly adrenal and thyroid hormones, is essential before NFPA surgery to reduce morbidity and mortality. 1

Comprehensive Endocrine Evaluation

• Complete assessment of all anterior pituitary hormone axes is mandatory preoperatively, as hypopituitarism is present in 37-85% of NFPA patients 1
• Specific preoperative endocrine testing should include:
  • Adrenal axis: Morning cortisol and ACTH levels; consider ACTH stimulation test if results are equivocal 1
  • Thyroid axis: Free T4 and TSH 1
  • Gonadal axis: FSH, LH, testosterone (men), estradiol (women) 1
  • Growth hormone axis: IGF-1 1
  • Prolactin: To rule out hyperprolactinemia or prolactinoma 1

Hormone Replacement Therapy

• Replacement for adrenal insufficiency and significant hypothyroidism must be initiated preoperatively (Level II recommendation) 1
• Glucocorticoid replacement should be started immediately when adrenal insufficiency is diagnosed (present in 17-62% of patients) 1
• Thyroid hormone replacement should be initiated for central hypothyroidism (present in 8-81% of patients) 1
• Sex hormone replacement is generally not urgent and can be addressed postoperatively 1

Imaging Assessment

• High-resolution MRI is the standard preoperative imaging modality (Level II recommendation) 1
• CT scanning may be used as a supplement to MRI, particularly to evaluate bony anatomy (Level III recommendation) 1
• Imaging should assess:
  • Tumor size and extension
  • Invasion of cavernous sinus
  • Compression of optic chiasm
  • Relationship to surrounding structures 1

Ophthalmologic Evaluation

• Complete neuro-ophthalmologic examination is recommended preoperatively 2
• Visual field testing should be performed to document any deficits 2, 3
• Visual acuity assessment should be completed 2
• Documentation of preoperative visual status is crucial for postoperative comparison 3

Additional Preoperative Considerations

• Exclude functioning adenoma by measuring:
  • Prolactin levels (25-65% of NFPA patients have mild hyperprolactinemia due to stalk effect) 1
  • IGF-1 levels to rule out clinically silent GH-secreting tumors (Level III recommendation) 1
• Discontinue anticoagulants and antiplatelet medications according to standard perioperative protocols 4
• Assess for sinonasal pathology that might affect the surgical approach 2
• Document baseline neurological status 2

Common Pitfalls to Avoid

• Failure to identify and treat adrenal insufficiency preoperatively can lead to adrenal crisis during surgery 1
• Mistaking stalk effect hyperprolactinemia (typically <200 ng/mL) for a prolactinoma 1
• Overlooking silent functioning adenomas (especially GH-secreting) that may require different management approaches 1
• Inadequate documentation of baseline visual and endocrine function, which makes postoperative assessment of improvement difficult 3

Perioperative Management

• Stress-dose steroids should be administered perioperatively in patients with known or suspected adrenal insufficiency 1
• Monitor fluid and electrolyte balance carefully, particularly for signs of diabetes insipidus 1
• Prepare for possible complications including CSF leak, meningitis, and vascular injury 2

By following these evidence-based preoperative instructions, the endocrinologist can help optimize the patient's condition before NFPA surgery, potentially improving surgical outcomes and reducing perioperative morbidity and mortality.