- Mass effect, especially on the optic apparatus.
- Hormonal excess states: acromegaly (GH production), Cushing’s (ACTH production), and secondary hyperthyroidism (TSH production).
- Second-line therapy for prolactinomas, in the following cases:
- Tumours that don’t respond adequately to dopamine-agonists (10-15% of prolactinomas).
- Patients who cannot tolerate dopamine-agonists or who prefer surgery over medical therapy.
The choice of surgical approach depends on the technical aspects of the case and the experience of the surgeon. The three main approaches are: craniotomy, transsphenoidal microsurgery, and the transsphenoidal endoscopic approach. The transsphenoidal approach is associated with lower morbidity and a lower rates of incomplete resection.
Perioperative Endocrine Management
- Hypopituitarism, especially cortisol and thyroid hormone deficiencies, should be corrected with hormone replacement prior to surgery. Similarly, diabetes insipidus should be corrected with ddAVP.
- In patients with confirmed or suspected cortisol deficiency, perioperative steroids coverage should be provided. E.g., hydrocortisone 50 mg 1 hour prior to surgery then 50 mg q8h for 24 hours then taper down home dose.
- Immediately after surgery, monitor the patient for signs of cortisol deficiency, such as reduced appetite, nausea +/- vomiting, dizziness, hyponatremia, and/or hypoglycemia. This is due to disruption of ACTH release.
- Immediately after surgery, monitor the patient for signs of diabetes insipidus: serum sodium (high), plasma osmolality (high), urine output (high), urine osmolality (low), and urine specific gravity (low). If confirmed, treat that with ddAVP. This may be transient.
- One week after surgery, some patients develop transient SIADH (hyponatremia). Counsel the patient on the symptoms of hyponatremia and provide them with a requisition to repeat their sodium level. If SIADH is confirmed, it should be managed with water restriction and close monitoring of sodium levels. This phase is temporary, lasting for about one week and may be followed by return of diabetes insipidus, in which sodium levels will be high and water restriction is dangerous.
- Similar to cortisol deficiency, disruption to TSH release may lead to central hypothyroidism. However, because thyroxine (T4) has a long half-life (~ 7 days), the deficiency may not manifest until later. Patients free T4 levels should be checked 3-5 weeks after surgery.