Pituitary Axis Basics

Question 0

Posterior pituitary

Answer 0

Stores ADH (vasopressin) and oxytocin
Produced in anterior hypothalamic nuclei

Question 1

Releasing factors

Answer 1

Produced in hypothalamus
Reach pituitary via portal system - in pituitary stalk
Inhibit/stimulate production hormones from district cell types

Question 2

Benign pituitary adenomas

Answer 2

Most common form pituitary disease
Symptoms arise due to increased/decreased hormone production
Or local affects tumour (bitemporal hemianopia)

Question 3

Three major conditions caused by secretion from pituitary adenomas

Answer 3

Growth hormone excess - acromegaly / giganticism
Prolactin excess - galactorrhoea / clinically silent
Excess ACTH - Cushing’s disease / Nelson’s syndrome

Question 4

Local affects of pituitary adenomas

Answer 4

Optic chasm - bitemporal hemianopia
Cavernous sinus - CN III, IV, VI lesions (eye movements)
Headaches due to pressure on meninges
Pressure on hypothalamic centres - obesity, altered thirst/appetite

Question 5

Investigations in space occupying pituitary lesions

Answer 5

MRI confirm diagnosis
Assess local pressure/infiltration - clinical tests eg eye movement
Assess hormone over/under production

Question 6

Hypopituitarism

Answer 6

Due to deficiency at level of hypothalamus / pituitary
Multiple deficiencies often due to tumour/destructive lesions
Commonest cause pituitary/hypothalamic tumour, or it’s treatment

Question 7

Acromegaly and giganticism

Answer 7

Pituitary hyper secretion of GH
Giganticism in children before fusion of long bones
Acromegaly almost always due to benign pituitary GH producing tumour
Incidence highest middle age, M=F