Session 8: Pituitary Disorders

Question 1

Common clinical presentations of pituitary tumours.

Answer 1

Mass effect of tumour leading to headache and visual loss.

The visual loss depends on how the pituitary tumour grows.

Superior growth leads to visual field loss in form of bitemporal hemi-anopia by pressure on optic chiasm.

If there is lateral growth of the tumour it can lead to pain and double vision.

If it invades the cavernous sinus cranial nerve palsy may ensue like Horner’s syndrome and ptosis.

Question 2

What happens to the hormones of the pituitary in the case of hypopituitarism?

Answer 2

GH, LH/FSH, TSH and ACTH goes down since they are under positive control.

Prolactin goes up because it is under negative control.

Question 3

What is the usual order of loss of hormones due to pituitary tumour?

Answer 3

GH -> LH -> FSH -> TSH -> ACTH -> PRL

Question 4

Following the order of how hormone secretion is usually affected in a growing pituitary tumour how will the different stages manifest itself?

Answer 4

GH deficiency leading to reduced quality of life in adults and short stature in children.

Gonadotropin deficiency leading to loss of secondary sexual characteristics in adults and loss of periods. Erectily dysfunction and trouble conceiving.

TSH and ACTH deficiency is life-threatening and can lead to Addison’s disease and hypopituitarism.

TSH deficiency leads to low thyroid hormones, cold, weight gain, tiredness, slow pulse and low T4 and non-elevated TSH.

ACTH deficiency leads to low cortisol, tiredness, dizziness, low BP, low sodium.

Question 5

What are the most common pituitary tumours causing excess of hormone secretion?

Which are rare?

Answer 5

Prolactin, GH and ACTH.

TSH and LH/FSH are rare.

Remember that this is tumours causing excess and not deficiency.

Question 6

How do you test the thyroid axis?

Answer 6

functional T4 and TSH

Question 7

How do you test the gonadal axis?

Answer 7

LH and FSH

Testosterone or oestradiol

Question 8

How do you test prolactin axis?

Answer 8

Serum prolactin

Question 9

How do you test HPA axis?

Answer 9

09.00 cortisol

Question 10

How do you test growth hormone axis?

Answer 10

GH and IGF-1

Question 11

What are dynamic assessments of HPA and GH axes?

Answer 11

Stimulation tests and suppression tests.

Question 12

When would you do a stimulation test or a suppression test?

Answer 12

Stimulation test when you suspect hormone deficiency

Suppression test when you suspect hormone excess

Question 13

Give examples of tests of the adrenal axis suspecting deficiency of ACTH.

Answer 13

Direct stimulation of adrenals by ACTH like synACTHen

Response to hypoglycaemic stress because insulin stress test.

Question 14

Give examples of test suspecting excess of adrenal axis.

Answer 14

Suppression of ACTH axis with steroids like dexamethasone.

This is to see if ACTH goes down in response to the increased dexamethasone. If the ACTH goes down you can expect a pituitary adenoma. If ACTH stays high you can expect an ectopic tumour like small cell lung cancer.

Question 15

Give examples of tests suspecting either deficiency or excess of GH axis.

Answer 15

Deficiency do a hypoglycaemic stress test (insulin stress test)

Excess suppress the GH axis with glucose load to check the glucose tolerance. (Glucose tolerance test)

Question 16

In addition to serum and dynamic tests how can you assess a suspect pituitary disorder?

Answer 16

By MRI

Question 17

How are macro-prolactinomas best treated?

Answer 17

With dopamine agonist because it will start shrinking. Kind of use it or lose it.

Question 18

If the prolactin levels are unusually low even for a prolactinoma but still elevated (<5000) what might you expect?

Answer 18

A tumour pressing on the stalk making dopamine unable to inhibit the secretion of prolactin. This means that the tumour doesn’t secrete prolactin itself but rather inhibits dopamine from making its way to the lactotropes.

Question 19

So if prolactin is >5000 suspect a prolactinoma

If <5000 suspect a tumour blocking dopamine from inhibiting prolactin secretion.

Why is this important?

Answer 19

Because prolactinomas can usually be treated surgically but non-functioning pituitary tumours cannot. They must be treated surgically.

Question 20

How might hormone levels present in a non-functioning pituitary adenoma?

Answer 20

All other hormones (LH/FSH, ACTH, TSH and GH) might be low but prolactin might be high.

Question 21

Give example of dopamine antagonists and their side-effects.

Answer 21

Anti-sickness and anti-psychotic drugs.

They can cause high prolactin levels (hyperprolactinaemia)

This means that it is important to check medication before sending patient away. Also check for pregnancy.

Question 22

Long-term complications of untreated acromegaly.

Answer 22

Premature cardivascular death

Inreased risk of colonic tumours

Probably increased risk of thyroid cancer

Disfigured body which may be irreversible

Hypertension and diabetes

Unpleasant symptoms in general

Question 23

Tests to confirm acromegaly.

Answer 23

OGTT with GH response

Failure to suppress GH

Elevated IGF-1 levels

Question 24

Treatment of acromegaly

Answer 24

Surgical removal

Additional treatment such as dopamine agonists to reduce GH secretion like Cabergoline and bromocriptine.

Somatostatin analogues

Pegvisomant which is a GH receptor blocker.

Radiotherapy

Question 25

What is diabetes insipidus?

Answer 25

There are two types: Cranial DI and Nephrogenic DI.

Cranial DI is becasuse of vasopressin (ADH) deficiency in pituitary disease.

Nephrogenic DI is due to vasopressin (ADH) resistance in kidney disease.

Question 26

Types of pathology that cause cranial DI.

Answer 26

Inflammation

Infiltration

Malignancy

Infection

Question 27

Why is it uncommon for a tumour to cause cranial DI?

Answer 27

Because standard pituitary tumours just affect anterior pituitary not posterior.

Question 28

Consequences of untreated DI.

Answer 28

Severe dehydration

Hypernatraemia

Reduced consciousness, coma and death.

Question 29

How do you treat cranial DI?

Answer 29

Synthetic vasopressin like desmopressin which is either nasal spray, tablets or injection.

Question 30

Clinical presentation of pituitary apoplexy (stroke either by haemorrhage or infarction)

Answer 30

Sudden onset headache

Double vision

Visual field loss

Cranial nerve palsy

Hypopituitarism