Pituitary Disease

Question 1

Describe the location of the pituitary gland?

Answer 1

Question 2

Arterial supply of the pituitary gland?

Answer 2

Question 3

Anterior Pit Hormones?

Answer 3

Question 4

Hormone regulation in the anterior pit?

Answer 4

Question 5

Thyroid Reg?

Answer 5

Question 6

gonadotrophin reg?

Answer 6

Question 7

growth hormone reg?

Answer 7

IGF mediates it

Question 8

Oxytocin causes?

Answer 8

Uterine contraction. It is stimulaterd by distension of the cervix.

Question 9

Posterior Pit hormones?

Answer 9

Oxytocin

ADH

Question 10

What inhibits AVP/ADH?

Answer 10

a decrease in plasma osmolality (not thirsty)

Thirsty (high plasma orsmolalitt).

Question 11

Exampples of pituitary and parapituitary tummours?

Answer 11

Pit - Pituitary Adenoma

Parapituitary tumours (craniopharyngiomas, meningiomas)

Question 12

Causes of hypopituitarism?

Answer 12

Pituitary (Pituitary adenoma) and parapituitary tumours (e.g. craniopharyngiomas, meningiomas)
Post-pituitary surgery
Post-radiotherapy to the pituitary or general irradiation to the brain (e.g in the treatment of childhood leukaemia)
Infarction (loss of blood supply) – ‘pituitary apoplexy’ (e.g. Sheehan’s syndrome)
Infiltration/inflammation e.g. sarcoidosis, lymphocytic hypophysitis (autoimmune)
Infection e.g. TB
Trauma e.g. head injury
Congenital
Functional e.g. psychosocial deprivation, weight loss, anorexia nervosa, athlete’s syndrome

Question 13

Features of hypopituitarism?

Answer 13

Often non-specific:
Lack of energy
Fatigue
Weight gain

Related to specific hormone deficiencies
GH deficiency
LH/FSH deficiency
TSH and ACTH deficiency
Alterations in PRL secretion
Oxytocin,AVP deficiency

Question 14

Gonadotropin Deficiency?

Answer 14

Question 15

ADH/AVP deficiency clinical symptoms?

Answer 15

Deficiency of AVP leads to cranial diabetes insipidus
Polyuria (large volumes of dilute urine >3L/24 h), polydypsia
Not usually seen with pituitary tumours (but can occur as a complication of pituitary surgery)
Commoner with inflammatory diseases (e.g. sarcoidosis, hypophysitis) or other tumours (e.g. craniopharyngioma

Question 16

how to investigate hypopituitarism?

Answer 16

Measurement of the basal pituitary or target gland hormones
Free T4, TSH, PRL, LH, FSH, testosterone (men) or oestradiol (women), IGF-1 and cortisol/ACTH
Stimulation test needed to confirm GH and cortisol deficiency
Insulin stress test (which will assess both)
If contraindicated synacthen test for cortisol deficicency and appropriate stimulation test for GH

Question 17

adequate stress test?

Question 18

when to measure synacthen test?

Answer 18

measure cortisol before and 30 mins after.

Question 19

how to investigate posterior dysfunction?

Answer 19

If clinically indicated, water deprivation test
Deprive of fluid for up to 8 hours
Measure plasma and urine osmolality and urine volume
Desmopressin (AVP analogue) given at the end if needed to distinguish between cranial and nephrogenic diabetes insipidus
Normal body response as osmolality and thirst etc goes up is to try to conserve water:
AVP secretion will rise and the urine will become concentrated (osmolality >800)
If cranial diabetes insipidus, urine will fail to concentrate and the patient will continue to pass large volumes of urine

Question 20

Urine Osmolality?

Answer 20

Question 21

how much does growth hormone cost?

Answer 21

£3000/year

Question 22

benefits of growth hormone replacmenet?

Answer 22

Improves quality of life (NICE approved)
Reduces fat mass and increases lean muscle mass
Benefical effect on lipids

Question 23

hormone replacments?

Answer 23

Thyroxine (tablets)
Hydrocortisone (tablets)
Testosterone (men; gels, patches, injections)
Oestrogen (women; oral contraceptive pill or HRT)
DDAVP (‘desmopressin’) if cranial diabetes insipidus (nasal spray or tablets)

Question 24

commonest cause of hypopituitarism?

Answer 24

Pituitary tumours

Benign and slow growing

Up to 10% of the population affected (incidental MRI findings increasingly common) but most will never come to clinical attention
Cause problems through:
Hormone excess syndromes
Hormone deficiency syndromes (already discussed)
Local pressure effects

Question 25

Local pressure effects of a pituitary tumour?

Answer 25

Headaches If upward extension towards optic nerves then visual disturbance: Loss of visual acuity Visual field defects (outer part of vision – bitemporal hemianopia) If sideways extension: Cranial nerve palsies

Question 26

How to classify pituitary tumours?

Answer 26

Size Microadenoma (\<1cm) Macroadenoma (\>1cm) Hormone-secreting or not Prolactinoma (commonest, approx 40%) Non-functioning (commonest needing surgery) 20-30% Acromegaly (GH tumours) 10-15% Cushing’s disease (ACTH tumours) 10-15% TSHoma and true LH/FSH secreting tumours (causing clinical hormonal excess) very rare Hypopituitarism is unusual in microadenomas but common in macroadenomas

Question 27

when do the pituitary tumurs commonly present?

Answer 27

midle-late life

Question 28

second commonest pituitary tumpur?

Answer 28

non functioning pituitary tumour

Question 29

if large adeonma what should you do?

Answer 29

surgery + radiotherapy

Question 30

symptoms of porlactin excess?

Answer 30

Women Oligomenorrhoea/amenorrhoea Galactorrhoea Infertility Hirsutism/acne\* Men Reduced libido Impotence Infertility Galactorrhoea\*

Question 31

symptoms of enlarged tumour?

Answer 31

Headache Visual failure Cranial nerve palsies

Question 32

symptoms of pituitary hormone deficiency?

Answer 32

Microprolactinoma - usually normal Macroprolactinoma - varying degrees of hypopituitarism

Question 33

causes of hyperprolactinaemia?

Answer 33

Stress (venepuncture?) Pregnancy Lactation Anti-emetics e.g. metoclopramide, domperidone, prochlorperazine Phenothiazines e.g. chlorpromazine Antidepressants

Question 34

pathological causes of hyperprolactinaemia?

Answer 34

Primary hypothyroidism Pituitary tumours Prolactinoma Growth hormone-secreting (30% acromegalics) Non-functioning (stalk compression) PCOS (10%) Hypothalamic lesions (rare) e.g. sarcoidosis Chest wall stimulation e.g. post-herpes zoster Liver or renal failure

Question 35

levels of prolactin?

Answer 35

macroprolactinomas tend to have much higher readings (e.g. \>10,000; normal \<500-600) MRI scan

Question 36

treat prolactinaemia?

Answer 36

Drugs – bromocriptine or cabergoline Very effective in normalising prolactin levels (85-90% patients) and restoring normal menstrual periods/ovulation etc If not tolerated or macroprolactinoma not shrinking, then surgery may be considered but rarely needed

Question 37

features of acromegaly?

Answer 37

Coarse facial features Enlargement of supraorbital ridges Soft tissue thickening e.g. lips Separation of teeth Prognathism Macroglossia Enlargement of the hands and feet Headaches Excessive sweating Hypertension Impaired glucose tolerance/type 2 diabetes Goitre

Question 38

treatment for pituitary tumour?

Answer 38

Surgery (transsphenoidal) usually first line ‘Cure’ depends on tumour size principally but also skill of surgeon 50% cure for macroadenomas 80-90% cure for microadenomas