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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.

PRE-OPERATIVE MANAGMENT

  • 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.

ON DISCHARGE

  • 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 (Ā±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.