pituitary adenoma

Question 1

what is a pituitary adenoma

Answer 1

a benign tumour of the pituitary gland which nearly always occurs in the anterior pituitary

Question 2

pituitary carcinomas are

Answer 2

exceptionally rare

Question 3

pituitary adenomas are classified according to

Answer 3

size and functionality

Question 4

classification according to size

Answer 4

• micro adenoma: 1cm or less

- macro adenoma: more than 1cm

Question 5

classification according to functionality

Answer 5

• non-functioning pituitary adenoma

- functioning pituitary adenoma

Question 6

non-functioning pituitary adenoma

Answer 6

a pituitary adenoma which does not secrete hormones

Question 7

at the time of diagnosis

Answer 7

most are macroadenoams as patients mostly present with symptoms caused by the adenoma comprising adjacent nerve

Question 8

most commonly compressed structures are

Answer 8

• optic chiasm

- cranial nerve 3,4,6 (run within the cavernous sinus)

Question 9

compression of the optic chiasm causes

Answer 9

bitemporal hemianopsia (loss of vision in the temporal field)

Question 10

compression of cranial nerve 3

Answer 10

the occulosmotor nerve supplies the inferior oblique, superior, medial and inferior rectus muscles of the eye (extra-occualr muscles), and the muscle sphincter of the iris, damage will cause difficulty with eye movement and a dilated pupil (mydriasis)

Question 11

compression of cranial nerve 4

Answer 11

the trochlear nerve suppose the superior oblique muscle, compression will cause difficulty with the downward eye movement

Question 12

compression of cranial nerve 6

Answer 12

the abducent nerve supplies the lateral rectus muscle, damage will result in ability to abduct the eyeball

Question 13

what else can non-functioning adenoma cause

Answer 13

hypopituarism

Question 14

growth hormone

Answer 14

is usually the first hormone to be lost, however, in adults it is not clinically obvious as it only causes lethargy, muscle weakness and increased fat mass, in children it can be more easily picked up

Question 15

the new hormone lost is usually

Answer 15

FSH and LH, in males this causes loss of libido and gynaecomastia, in females causes oligomennorhoea or ammenorrhoea

Question 16

the next hormone lost is

Answer 16

ACTH which causes symptoms go corticol insufficiency (but unlike primary adrenal insufficiency the RAAS is still intact so plasma potassium concentration is unaffected) but it can cause postural hypotension and extreme pallor (due to loss of MSH)

Question 17

last hormone to be lost is

Answer 17

TSH which causes secondary hypothyroidism

Question 18

pituitary adenoma can do what to prolactin levels

Answer 18

causes increased prolactin due to the stalk affect caused by compression of the infundibulum so dopamine cannot flow down and inhibit its release

Question 19

management of non-functional adenoma

Answer 19

resection if compressing structures of hormone replacement

Question 20

other causes of hypopituitarism of the anterior pituitary

Answer 20

• local brain tumours
• trauma
• infection
• infarction
• granulomatous disease
• empty sell syndrome

Question 21

local brain tumours causing hypopituitarism

Answer 21

craniopharyngioma, meningioma, glioma, astrocytoma

Question 22

trauma causing hypopituarism

Answer 22

road traffic accident, iatrogenic

Question 23

infection causing hypopituitarism

Answer 23

meningitis

Question 24

granulomatous causes of hypopituitarism

Answer 24

TB, sarcoidosis, hstiocytosis x

Question 25

infarctive causes of hypopituitarism

Answer 25

pituitary apoplexy and sheehans syndrome

Question 26

pituitary apoplexy

Answer 26

haemorrhage into the pituitary usually caused by the existence of an adenoma which destroys the pituitary gland
- requires surgical decompression

Question 27

sheehans syndrome

Answer 27

disease specific to pregnancy, postpartum ischaemic necrosis of the pituitary, usually noticed because the woman cannot breastfeed or if the woman hasn’t had a period from about a year after pregnancy (remember if someone breastfeeding they won’t have a period)

Question 28

empty sella syndrome

Answer 28

• not a clinical diagnosis only a radiological finding
• the pituitary gland is shrunk or flattened within the sella turcica which becomes with cerebrospinal fluid
• pituitary gland usually functions normally but it can cause hypopituarism

Question 29

MANAGEMENT OF HYPDOPITUARISM

Answer 29

replace the hormones they lack

• if low ACTH= hydrocortisone
• if low TSH=levothyroxine
• if low LH+ FHS= oestrogen and progesterone or testosterone
• if low GH= growth hormone therapy

Question 30

why is growth hormone therapy given to adults

Answer 30

increases well being, reduces abdominal fat, increases muscle mass cardiac function and bone density

Question 31

testosterone replacement

Answer 31

sustanton IM injection every 3-4 weeks

Question 32

side effects of testosterone replacement

Answer 32

• does NOT cause prostate cancer but if someone already has prostate cancer it accelerates its growth
• polycythaemia by increasing haematocrit which can cause blood clots
• oral tablets can cause hepatitis