Lecture 16

Question 1

What is the most common cause of pituitary malfunction?

Answer 1

Bengin tumour= Adenoma

Question 2

How common are disorders of the pituitary gland?

Answer 2

Rare

Question 3

What are the 2 types of pituitary tumours?

Answer 3

Non-functioning: Do not produce any hormone. Result in inadequate production of one or more pituitary hormones due to physical pressure on glandular tissue

Functional: Cause problems with overproduction of one or more of the pituitary hormones

Question 4

How do pituitary tumours affect the patient clinically?

Answer 4

Non-functioning: headaches, visual problems (compression of optic nerve), vomiting, nausea

Functional: systemic effects of the over secreted hormone

Question 5

How would you investigate/diagnose a suspected pituitary tumour?

Answer 5

1. Locate the anatomy, size and location of mass- MRI scan
2. Assess visual field defects
3. Assess endocrine function by measuring levels of hormones in blood (excess/deficiency)

Question 6

What is hypopituitarism and its causes?

Answer 6

Insufficient pituitary hormone production
Causes:
-pituitary adenoma
-radiation therapy
-inflammatory disease
-head injury

Question 7

In what order are the pituitary hormones lost?

Answer 7

GH and LH/FSH lost first, then TSH and ACTH, lastly PRL
ADH and oxytocin are only significantly affected if tumour affects hypothalamic function/inflammatory process is involved

Question 8

What is panhypopituitarism?

Answer 8

Deficiency of all anterior pituitary hormones

Question 9

What does GH deficiency in adults/children result in?

Answer 9

Adults

• decrease in tolerance to exercise
• decreased muscle strength
• increased body fat
• reduced sense of well-being

Children

• poor growth
• short stature

Question 10

Why is GH deficiency hard to diagnose?

Answer 10

GH secretion is pulsatile

requires direct and indirect measurements

Question 11

What are the causes of GH deficiency in children?

Answer 11

• idiopathic (unknown)
• gene mutations in GHRH receptor
• autoimmune inflammation

Question 12

Does GH deficiency have any effect on fetal growth?

Answer 12

Little

-can result in hypoglycaemia/jaundice

Question 13

How do you treat GH deficiency?

Answer 13

GH is manufactured by recombinant DNA technology

Question 14

What does a gonadotropin deficiency cause?

Answer 14

• lack of libido (sexual desire)
• infertility
• infrequent periods (oligomenorrhea)
• no periods (amenorrhea)
• impotence (erectile dysfunction/failure to orgasm)

Question 15

What causes a deficiency of ADH?

Answer 15

• hypothalamic tumour
• pituitary tumour that has extended up into the hypothalamus
• cranial radiotherapy
• pituitary surgery
• autimmune infiltration
• infections (meningitis)

Question 16

What does insufficient ADH release lead to?

Answer 16

Excess excretion of dilute urine resulting in dehydration, and an increasedsensation of thirst (polydipsia)
=DIABETES INSIPIDUS

Question 17

What are the 3 main conditions caused by excess pituitary hormone production due to hypersecreting pituitary adenoma?

Answer 17

• prolactin excess
• growth hormone excess
• ACTH excess

Question 18

What does excess secretion of ACTH cause?

Answer 18

Cushing’s syndrome

Question 19

What dominates the function/secretion of prolactin?

Answer 19

Inhibition of prolactin secretion by dopamine dominates

Question 20

What is the most common form of pituitary disorder?

Answer 20

Hyperprolactinaemia (high prolactin level in blood)

Question 21

What are the symptoms of hyperprolactinaemia?

Answer 21

• galactorrhoea (unexplained milk production-rare in men)
• gynecomastia (hard breast tissue)
• hypogonadism (diminshed activity of testes/ovaries)
• amenorrhea (no period)
• erectile dysfunction

Question 22

Why does hypogonadism arise from hyperprolactinaemia?

Answer 22

• high levels of dopamine due to negative feedback from increased plasma prolactin
• high levels of dopamine inhibits GnRH/LH/FSH secretion from anterior pituitary

Question 23

What is the most common cause of hyperprolactinaemia?

Answer 23

Prolactinoma- pituitary adenoma which secretes prolactin

-pregnancy, suckling, stress, exercise, drugs, antidepressants can also cause it

Question 24

How do you treat prolactin excess?

Answer 24

• dopamine receptor agonists (cabergoline)
• trans-sphenoidal surgery (access pituitary through nose)
• radiotherapy

Question 25

What do growth hormone secreting adenomas cause and how?

Answer 25

-headache -visual field defects -cranial nerve palsies (they are usually large) Direct actions of GH itself and via stimulation of IGF-1 production

Question 26

How long does GH excess take to manifest?

Answer 26

Several years (can be up to 6 years)

Question 27

What are some changes in physical appearance in GH excess?

Answer 27

- broad nose - coarse facial features - thick lips - prominent supraorbital ridge (crest bone on frontal lobe of skull) - enlargement of hands and feet - skin is greasy with excessive sweating - deepening of voice (hypertrophy of soft tissue in upper airways)

Question 28

What is the condition where there is excessive GH secretion in children (before fusion of epiphyseal plates)?

Answer 28

Gigantism | rarely develops now due to early diagnosis and treatment

Question 29

What does GH antagonise?

Answer 29

The actions of insulin | therefore diabetes mellitus may develop

Question 30

What have the increase in IGF-1 levels in GH excess been associated with?

Answer 30

Some forms of cancer

Question 31

What are the 3 treatment options for patients with acromegaly (too much GH in adults)?

Answer 31

- surgery to remove adenoma - radiation therapy - drug therapy

Question 32

How can you reduce GH levels with drugs?

Answer 32

- Dopamine receptor agonists - somatostatin which limits GH secretion has limited use due to short half life, but synthetic somatostatin analogs have been developed which produce prolonged suppression of GH secretion - antagonists of GH receptor (pegvisomant) is the most recent treatment

Question 33

In what nucleus of the hypothalamus is ADH made?

Answer 33

Supraoptic nucleus

Question 34

In what nucleus of the hypothalamus is oxytocin made?

Answer 34

Paraventricular nucleus

Question 35

What is pituitary apoplexy?

Answer 35

Sudden vascular event in a pituitary tumour