Operative Management of Pituitary Tumours

PRE-ADMISSION

Patient should have had:

Full endocrine assessment.
Neurosurgical assessment.
Neuro-ophthalmological assessment including Humphrey fields in previous 6/12
Baseline investigations:
CT/MRI brain
Free T4, TSH, prolactin, oestradiol (females), testosterone (males), FSH, LH, profile.
ECG and CXR if age >60 years.
IGF-1, GH, with oral GTT if clinically indicated
If prolactinoma confirmed, treat with dopamine agonist drug (eg. Cabergoline), then repeat CT/MRI scan (1-3 months after prolactin normalised or at minimum plateau). Surgery indicated if tumour non-responsive.
Check TFTs. If patient is hypothyroid need short synacthen test to exclude associated steroid dependency. Replace with T3 20 mcg tds for 4 days pre-op if surgery urgent, or thyroxine if surgery not imminent.
Cushing's disease: start patient on drugs, titrating to random cortisol 150-300 nmol/l:
Ketoconazole: 200 mg bd - needs weekly LFTs initially, can cause hepatitis
Metyrapone: 250 mg bd to 750 mg tds - side effects are lethargy, peripheral oedema, hirsutism
Etomidate: up to 3mg per hour by IV infusion.

Confirm neurosurgical operating date (day 0) with consultant neurosurgeon
Admit 2 days pre-op.
For trans-cranial surgery: dexamethasone 4 mg qds, start 1 day pre-op.
For trans-sphenoidal surgery:
Hydrocortisone 100 mg i.m. qds starting with pre-medication. (An IV infusion of 8.3 mg per hour (200 mg over 24 hours) is an alternative).

Write up:
Hydrocortisone 50 mg i.m. qds on day 1 (usually Friday). (Or an IV infusion of 4.2 mg per hour = 100 mg over 24 hours).
Day 2 (Sat) HC 15mg (at 6am)+ 10 mg (at noon) + 5 mg (at 6pm).
Day 3 (Sun) HC 15mg mane + 10 mg at noon (but omit evening dose of 5mg).
Day 4 (Mon) urgent morning cortisol sample needs to be sent to lab before next dose of hydrocortisone administered.
Continue with HC 10mg + 5mg + 5mg and discharge on this dose.
If complicated by post-op infection, continue with higher dose HC.
Interpretation of cortisol result (not Cushing's disease):
If cortisol >450 nmol/l, then can be sent home without hydrocortisone.
If 400 - 450 nmol/l, then use clinical grounds and pre-op assessment.
If < 400 nmol/l, then continue hydrocortisone.
Interpretation of cortisol result (if Cushing's disease):
If cortisol is detectable, then patient should be kept in for low dose dexamethasone suppression test.

Fluid balance charts should be kept. A spot urine osmolality is checked every 4 hours.
If urine output >1l per 4 hrs consider desmopressin (adult dose 0.5-1.0 mcg s.c. q6h). Prior to administration check paired plasma and urine osmolality.
DI is confirmed by the presence of a high plasma osmolality (>295) in the presence of an inappropriately low urine osmolality (U:P ratio <2:1). (urine SG < 1.005).
If the plasma osmolality is low the patient may be over-drinking due to a dry mouth. A low urine osmolality is appropriate.

Discharge drugs HC 10mg + 5mg + 5mg
Advise patient regarding increasing dose with illness etc.
Arrange electrolytes (esp Na) to be measured the following Monday (10 days postop) as there is a risk of hyponatraemia, especially if the patient had Cushing's disease.
Steroid card.
Pituitary stimulation tests and ITT (±OGTT for acromegaly) to be performed 3-4 weeks post-op following cessation of steroids from the night before test. Hydrocortisone to be resumed after test until results known.
Endocrine follow up should be 6 weeks post-op.
Joint pituitary endocrine clinic 3 months post-op
Radiotherapy referral if appropriate.
If patients have had Cushing's disease, and do not need hydrocortisone replacement, dexamethasone suppression tests should be performed regularly (at least yearly).
Urinary free cortisols can be used to monitor patients on hydrocortisone.