Pituitary tumours (non-functioning)

Question 1

Define non-functioning pituitary adenoma.

Answer 1

A tumour with no hypersecretion of hormone.

Question 2

What are most common pituitary adenomas? (functioning and non-functioning)

Answer 2

• Prolactinomas (35%)
• Somatotroph adenomas (20%)
• Corticotroph adenomas (10-12%)
• Gonadotroph adenomas (20%)
• Null cell adenomas (10%)
• Thyrotroph adenomas (1-2%)

Question 3

Give 3 neoplastic and non-neoplastic causes of bitemporal hemianopia.

Answer 3

NEOPLASTIC

• Pituitary macroadenoma
• Meningioma e.g. suprasellar
• Cranipharyngioma
• Chiasmatic glioma

NON-NEOPLASTIC

• Aneurysm or ectatic carotid artery
• Epidermoid cyst
• Sarcoid
• Dermoid cyst

Question 4

Describe the optic pathways.

Answer 4

NB the right side of something is processed with the left half of each retina etc.

Question 5

Describe some visual field defects caused by lesions in different parts of the visual pathway.

Answer 5

Question 6

How common are non-functioning pituitary tumours?

Answer 6

Non-functioning pituitary adenomas account for 15% of all pituitary adenomas

3rd most common intra-cranial neoplasm in adults

Small pituitary tumours (<4 mm) are common and often found incidentally

Question 7

Do non-functioning pituitary tumours produce any hormones?

Answer 7

They usually make at least one of the pituitary hormones even though they are called non-functioning

However the tumours appear non functioning because

• FSH and LH excess usually do not cause specific symptoms
• only parts/subunits of the hormone are produced which are not active
• they are secreted into blood in small amounts so blood levels are usually normal

Question 8

What are the signs and symptoms of CNFPAs?

Answer 8

• Usually asymptomatic so present late - rarely produce LH and FSH

Stretching of the dura around pituitary →

• Headaches - mass effect
• Imbalance, urinary incontinence - may cause dural stretch or cavernous sinus invasion

Compression of optic chiasm →

• double vision, visual field defects (18-78%) - 3rd, 4th, 6th cranial nerve palsies
• facial pain and paraesthesias - V1 and V2 branch of CN5 palsy

Depletion of hormone due to compression of normal functioning pituitary →

• hypopituitarism - gonadotrophs/somatotrophs are most susceptible to local pressure damage from pituitary adenoma
• hypogonadism, GH deficiency, hypothyroidism, adrenal insufficiency
• no hyperkalaemia as mineralocorticoid pathway is intact

CAN PRESENT WITH PITUITARY APOPLEXY

Question 9

What are the signs and symptoms of pituitary apoplexy?

Answer 9

• Severe headache
• Sudden onset
• Nausea
• Vomiting
• Fever
• Meningismus
• Altered GCS
• Visual disturbances
• Hypopituitarism

Precipitating factors: head injury, anticoagulant therapy, dopamine agonists, radiotherapy, dynamic endocrine tests

May be asymptomatic

Question 10

What investigations would you do for pituitary adenoma (nf)?

Answer 10

Pituitary MRI pre- and post-gadolinium enhancement - better than CT; shows tumour invasion into cavernous and sphenoid sinus and any mass effect.

Ophthalmic evaluation - Humphrey 30-2 test.

Routine blood tests - hormones, metabolic panel, FBC.

• Hyponatraemia - in adrenal insufficiency and hypothyroidism
• Anaemia - in hypogonadism, hypothyroid or adrenal insufficiency
• Lipid panel - hyperlipidaemia in hypogonadism

Hormone tests:

• Prolactin - elevated in prolactinoma or stalk compression
• IGF-1 - low or normal in GH deficiency
• LH/FSH
• testosterone, estradiol
• TSH, free thyroxine
• morning cortisol
• ACTH

Question 11

How do you manage CNFPAs? (not on Sofia)

Answer 11

Microadenoma → observation

Macrodenoma →

• Observation OR
• Surgery - trans-sphenoidal
• +/- Radiotherapy - if residual tumour after surgery; via gamma knife
• +/- Somatostatin analogues/DA - if residual tumour or recurrence after surgery and radiotherapy
• Hormone replacement - as shown by CPFT

Question 12

What is a normal prolactin level?

Answer 12

<600

Question 13

If prolactin is >6000 what is the diagnosis?

Answer 13

Prolactinoma is the only cause of such high prolactin

Question 14

Describe how a CPFT is carried out.

Answer 14

• Fast patient overnight
• Ensure good IV access
• Weight pt. and calculate dose of insulin required (0.15units/kg i.e. 70kg woman = 10.5units)
• Mix and IV. Inject the following (patient may vomit on injection):
  
  • Insulin 0.15 units/kg
  • TRH 200mcg
  • LHRH/GnRH 100mcg
• Take bloods at 0, 30 and 60 minutes of glucose, cortisol, GH, LH, FSH, TSH, prolactin and T4
• Take bloods at 90 and 120 minutes of glucose, cortisol and GH

Question 15

What is the diagnosis?

Answer 15

Functioning pituitary adenoma

Management:

• URGENT hydrocortisone replacement (fludrocortisone is not necessary as adrenals should still be able to make aldosterone as it is independent of the HPA)
• Total therapy (ordered):
  
  1. Hydrocortisone replacement
  2. Thyroxine replacement
  3. Oestrogen replacement
  4. GH replacement
  5. (Cabergoline or Bromocriptine – if prolactinoma is the cause of the failure –> shrinks tumour)
     
     • Dopamine agonists

Question 16

If a patient presents with bitemporal hemianopia and no other endocrine abnormalities, what is the diagnosis?

Answer 16

Non-functioning pituitary adenoma

Question 17

What is the diagnosis?

Answer 17

Disconnection hyperprolactinaemia (non-functioning pituitary adenoma).

• Adenoma presses on pituitary stalk
• Dopamine prevented from reaching anterior pituitary
• No -ve inhibition on prolactin release
• Hyperprolactinaemia

Question 18

Do you need to use rescue therapy in disconnection hyperprolactinaemia? What is the management of non-functioning pituitary adenoma?

Answer 18

No because they rescue themselves with adrenaline

BUT this still cuts off all the hypothalamic releasing hormones.

1. Hydrocortisone replacement
2. Thyroxine replacement
3. Oestrogen replacement
4. GH replacement
5. Cabergoline or Bromocriptine – brings down prolactin and allows women to ovulate and men to be fertile

Question 19

Name 3 effects of functional pituitary adenomas/their effects.

Answer 19

• Acromegaly
• Cushing’s syndrome
• Prolactinoma

Question 20

Define pituitary apoplexy.

Answer 20

Bleeding inside a tumour of the pituitary.

Question 21

What is the management of pituitary apoplexy?

Answer 21

Glucocorticoids +/- levothyroxine e.g. dexamethasone +/- levothyroxine given if required.

Surgery - if mass effect or neurological signs; trans-sphenoidal.

Hormone replacement - post-op

Observation - if no mass effect or neurological signs with MRI every 6-12 months

NB: this condition is life threatening because it may be associated with adrenal insufficiency.

Question 22

What are the complications of a pituitary adenoma?

Answer 22

Neurological deficits

Treatment related:

CSF rhinorrhoea - ~2%

Hypopituitarism - 2-15%

DI - ~33%

Surgical mortality

Meningitis - <1%

Radiation-induced optic neuropathy

Radiation-induced secondary malignancies