Pituitary

Question 1

What is the most common cause of a pituitary malfunction?

Answer 1

Benign tumour (Adenoma)

Question 2

How can a ‘non-functioning’ tumour result in inadequate production of one or more pituitary hormones?

Answer 2

Due to the physical pressure form the growing tumour on the glandular tissue.

Question 3

What issues can a pituitary tumour cause when you think about the pressure it applies to surrounding structures?

Answer 3

Headaches and visual problems (compression of the optic nerve), vomiting and nausea

Question 4

What are effects of a ‘functional’ pituitary tumour?

Answer 4

If depends, they correspond to the systemic effects of the over secreted hormone.
There may not be any negative feedback regulation of the hormone.

Question 5

What 3 things are involved with investigation a suspected pituitary tumour?

Answer 5

1. Delineation of anatomy, size and topographical location of the pituitary or parapituitary mass (usually by MRI scan)
2. Assessment of visual field defects
3. Assessment of endocrine function to determine whether there is hormonal excess or deficiency.

Question 6

How would you Assess the endocrine function to determine whether there is hormonal excess or deficiency?

Answer 6

1. Measuring the hormone levels in blood

2. staining sections from a biopsy of the tumour with antibodies for the relevant hormone

Question 7

What is hypopituitarism?

Answer 7

Insufficient pituitary hormone production

Question 8

What are the causes of hypopituitarism?

Answer 8

1. Pituitary adenoma
2. Radiation therapy
3. Inflammatory disease
4. Head injury

Question 9

What are the first hormones secreted by the anterior pituitary to be lost due to a pituitary adenoma?

Answer 9

GH and LH/FSH

Question 10

What is a deficiency in all anterior pituitary hormones referred to as?

Answer 10

Panhypopituitarism

Question 11

When might the secretion of ADH and oxytocin from the posterior pituitary be affected?

Answer 11

If a tumour is affecting the hypothalamic function

Or
If an inflammatory process in involved

Question 12

What effects would a growth hormone deficiency have on an adult?

Answer 12

Decreased exercise tolerance
Decreased muscle strength
Increased body fat
Reduced sense of ‘well being’

Question 13

Why is a GH deficiency so difficult to diagnose?

Answer 13

Because the secretion of it is pulsatile

Question 14

What effect does GH deficiency have on foetal growth?

Answer 14

Little effect

*sever prenatal deficiency can result in hypoglycaemia and jaundice

Question 15

What are the results of a gonadotropin deficiency? *called hypogonadism

Answer 15

Women: Lack of libido,
Infertility
Oligomenorrhoea (irregular periods) or amenorrhea

Men: decrease libido and impotence

Question 16

What are the causes of a ADH deficiency?

Answer 16

hypothalamic tumour
pituitary tumour that has extended up into the hypothalamus.

Other causes of ADH deficiency include cranial radiotherapy, pituitary surgery autoimmune infiltration and infections such as meningitis

Question 17

What are the consequences of ADH deficiency?

Answer 17

Excess excretion of dilute urine=dehydration and increased sensation of thirst (polydipsia)

*this condition represents the cranial form of the disease diabetes insipidus

Question 18

What are the three main conditions caused by excess pituitary hormone production from a hyersecreting pituitary adenoma?

Answer 18

Prolactin excess
Growth hormone excess
ACTH excess

Question 19

What secretes prolactin?

Answer 19

Lactotropes in the anterior pituitary

*stimulated by prolactin releasing hormone, inhibited by dopamine (more important control)

Question 20

What can hyperprolactinaemia cause, symptom wise?

Answer 20

1. Galactorrhea (unexplained milk production-rarer in men)
2. gynecomastia (hard breast tissue)
3. Hypogonadism
4. Amenorrhea
5. Erectile dysfunction

Question 21

What are the causes of hyperprolactinaemia?

Answer 21

Common: prolactinoma (pituitary adenoma that secretes prolactin)

Other causes: pregnancy, suckling, stress and exercise, drugs (antipsychotics and antidepressants)

Question 22

How is hyperporlactinaemia treated?

Answer 22

Using dopamine receptor agonists (ie cabergoline)

These stimulate dopamine secretion which in turn will inhibit prolactin secretion

Question 23

If using dopamine receptor agonists doesnt help someone with hyperprolactinaemia, what other treatments are there?

Answer 23

Trans-sphenoidal surgery)

Radiotherapy

Question 24

Why do growth hormone excess take so long to diagnose?

Answer 24

Because the effects of it will often take several years to manifest as a change in physical appearance
.

Question 25

What are the physical changes that appear when someone has growth hormone excess?

Answer 25

Broad nose
Coarse facial features
Thick lips
Prominent supraorbital ridge (eyebrow bone)

Enlargement of hands and feet
Greasy skin with excessive sweating

Deeper voice (due to hypertrophy of soft tissues of upper airways)

Question 26

What are further complications of a growth hormone excess, in relation to insulin and serum IGF-1 levels?

Answer 26

Insulin- Gh antagonises the action of insulin, therefore you get several metabolic complications ie diabetes mellitus

Serum IGF-1 levels- these rise and have been associated with some forms of cancers

Question 27

What are the treatments for those with acromegaly?

Answer 27

Surgery to remove adenoma
Radiation therapy
Drug therapy

Question 28

Give some examples of the types of drugs you might use to treat acromegaly?

Answer 28

Dopamine receptor agonists (need a high dose)
Somatostatin (short half life though so may need synthetic analog)
Antagonist of GH receptor (ie pegvisomant)

Question 29

What can ACTH excess lead to?

Answer 29

Cushing’ syndrome