Lecture 22: pituitary disorders

Question 1

Which diseases can result from a malfunction in the hypothalamic pituitary axis?

Answer 1

Malfunctions include pituitary or hypothalamic tumour.

• Gigantism
• Acromegaly
• Cushing’s syndrome

Question 2

Describe the clinical effect a non-functioning pituitary tumour would have.

Answer 2

They can result in inadequate production of 1+ ant. pituitary hormones due to the mass’ physical pressure on the gland.

Can also result in headaches, visual problems, nausea, vomiting due to the mass pressing on surrounding structures.

Question 3

Describe the clinical effect a functioning pituitary tumour would have.

Answer 3

They would cause hyperpituitarism as the tumour itself is also secreting pituitary hormones.

• prolactin excess
• GH excess
• Adrenocorticotropic hormone (ACTH) excess

Question 4

How would you investigate a patient’s pituitary tumour?

Answer 4

Give a description of its size, anatomy and topographical location via MRI.
Assess the patient’s visual field.
Assess whether the tumour is (non) functioning to confirm if excess/deficient in hormones.

Question 5

You are a junior doctor and want to confirm whether or not your patient has hyperpituitarism hypopituitarism. What endocrine tests would you do?

Answer 5

Measure the pituitary hormone levels in their blood

Retrieve a part of the tumour via biopsy then stain it using the hormones’ relative antibodies eg: GH antibodies.

Question 6

Define hypopituitarism and which hormones are usually affected first.

Answer 6

Insufficient pituitary hormone production resulting from a pituitary adenoma.
Usually GH, FSH/LH are affected first in APG.

Question 7

What is the term given when there is a deficiency of all the APG hormones?

Answer 7

Panhypopituitarism

Question 8

Would a pituitary tumour affect the secretion of OT and ADH?

Answer 8

Only if the tumour affects the hypothalamic function
OR
An inflammatory process is involved.

Question 9

Which hormones are deficient in hypopituitarism?

Answer 9

GH
Gonadotropin
TSH&ACTH
ADH

Question 10

Describe what can happen is GH deficiency.

Answer 10

• low exercise tolerance
• decrease muscle strength
• more body fat
• reduce sense of well being
• short stature
• children poor growth
• severe prenatal deficiency = hypoglycaemia + jaundice

Adults cause: pituitary adenoma
Children cause: unknown (mutations + autoimmune?)

Question 11

How can we treat patients with GH deficiency?

Answer 11

Manufactured GH is given as treatment.

Question 12

What happens in Gonadotropin deficiency (hypogonadism)?

Answer 12

Women…

• lack libido
• infertility
• oligomenorrhea
• amenorrhea

Men..

• decrease libido
• impotence

Question 13

What are some causes of ADH deficiency?

Answer 13

• Hypothalamic tumour
• Pituitary tumour
• Cranial radiotherapy
• Pituitary surgery autoimmune infiltration
• infections (meningitis)

Question 14

How can a pituitary and hypothalamic tumour cause ADH deficiency?

Answer 14

ADH produced in the hypothalamus so tumour would affect production.
Pituitary tumour could extend into the hypothalamus and affect the production.

Question 15

What symptoms would you experience if you had ADH deficiency?

Answer 15

• polyuria
• polydipsia (more thirsty)
• more dehydration
• more frequently urinating
• getting up at night to urinate

Question 16

Would diabetes mellitus or diabetes insipidus be relevant here? Why?

Answer 16

Diabetes insipidus follows with pituitary tumours as causes ADH deficiency.
DI is where you get polyuria and polydipsia due to lack of ADH.

DM is where you have a high blood glucose: polyuria, polydipsia and weight loss can result in this as the glucose>renal threshold.

Question 17

Define hyperpituitarism and which hormones could be in excess as a result.

Answer 17

• Prolactin
• GH
• ACTH

Question 18

Describe the regular function of prolactin and what symptoms you would see in hyperprolactinaemia.

Answer 18

Prolactin usually initiates and maintains lactation which is regulated by dopamine.

• galactorrhoea
• gynecomastia
• hypogonadism
• amenorrhea
• erectile disfunction

Question 19

What’s the most common cause for hyperprolactinaemia?

What else can cause this?

Answer 19

A functioning prolactinoma is the main cause.

• pregnancy
• suckling
• stress
• exercise
• antipsychotics
• antidepressants

Question 20

How could you treat a patient with hyperprolactinaemia?

Answer 20

-Dopamine receptor agonists are the 1st line of treatment as dopamine regulates prolactin secretion.
IF INSUFFICIENT
-Trans-sphenoidal surgery to remove prolactinoma.
-Radiotherapy

Question 21

If a GH secreting pituitary adenoma found in a patient, what symptoms would they have presented with?

Answer 21

• headaches
• visual field defects
• cranial nerve palsies
• change in physical features
• deeper voice
• gigantism
• acromegaly

Question 22

Describe which conditions are mainly associated with GH excess.

Answer 22

Gigantism: excessive endochondral ossification before epiphyseal plate closure so a lot taller than average.

Acromegaly: larger extremities that usually occurs in adults.

Question 23

Why is gigantism so rare?

Answer 23

Only occurs from birth and early diagnosis and treatment prevent further progression.

Question 24

Why can diabetes mellitus sometimes develop with GH excess?

Answer 24

GH antagonises (inhibits) insulin so people with GH excess will have high blood glucose. This leads to DM as no uptake of insulin is possible.

Question 25

Why GH excess quite dangerous?

Answer 25

It inhibits insulin leading to diabetes and a higher blood IGF1.
The latter has been linked to some forms of cancer.

Question 26

What are the 3 types of treatment used for acromegaly patients?

Answer 26

• surgery to remove the adenoma
• radiation therapy
• drug therapy

Question 27

Somatostatin is a hormone that reduces GH secretion. Why isn’t it used to treat GH excess?

Answer 27

Somatostatin has a very short half life so it has a limited use.
However, somatostatin analogues have been produced with a prolonged effect.

Question 28

Which condition does ACTH excess cause?

Answer 28

Cushing’s syndrome