Operative Management of Pituitary Tumours
Patient should have had:
- Full endocrine assessment.
- Neurosurgical assessment.
- Neuro-ophthalmological assessment including Humphrey fields in previous 6/12
- Baseline investigations:
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).
POST-OPERATIVE MANAGEMENT OF HYDROCORTISONE
- 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.
POST OPERATIVE MANAGEMENT OF DIABETES INSIPIDUS
- 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.