S8) Pituitary Disorders Flashcards Preview

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Flashcards in S8) Pituitary Disorders Deck (30)
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1

Disorders of the pituitary gland are relatively rare. 

What is the most common disorder?

The most common cause of pituitary malfunction is a benign tumour (adenoma)

2

Most pituitary tumours are “non-functioning”.

What does this mean?

Non-functioning pituitary tumours contain tumour cells which themselves do not produce any hormone

3

What is the usual consequence of non-functioning pituitary tumours?

These tumours can result in inadequate production of 1/more pituitary hormones due to physical pressure from the growing tumour on glandular tissue

4

What are the clinical symptoms of non-functioning pituitary tumours?

Pressure on surrounding structures in the vicinity of the tumour result in:

- Headaches

- Visual problems (optic nerve)

- Vomiting

- Nausea 

5

Functional pituitary tumours are quite rare.

What does this mean?

Hypersecreting (functional) pituitary tumours contain tumour cells involved in the overproduction of 1/more of the pituitary hormones 

6

What are the clinical symptoms of functional tumours?

The clinical symptoms of hypersecreting tumours usually correspond to the systemic effects of the over secreted hormone 

7

Outline the clinical approach in the investigation of a suspected pituitary tumour

- Delineation of the anatomy, size and topographical location of pituitary / parapituitary mass (MRI scan)

- Assessment of visual field defects

- Assessment of endocrine function to determine hormonal excess/deficiency

8

How might one assess the endocrine function in a patient with a suspected pituitary tumour?

- Measure hormone levels in blood

- Staining sections from a biopsy of the tumour with antibodies for the relevant hormone

9

What is hypopituitarism?

Hypopituitarism is a state of insufficient pituitary hormone production, commonly due to a pituitary adenoma and rarely due to radiation therapy, inflammatory disease or head injury

10

In light of hypopituitarism, what is the consequence of the adenoma?

Progressive loss of anterior pituitary function (GH and LH/FSH first)

11

What is panhypopituitarism?

Panhypopituitarism is the deficiency of all anterior pituitary hormones

12

Why aren't ADH and oxytocin secretion usually impaired in hypopituitarism?

Secretion of ADH and oxytocin from the posterior pituitary is usually only significantly affected if the tumour affects hypothalamic function

13

What are some causes of GH deficiency?

- Mass defects from pituitary adenoma

- Specific gene mutations e.g. GH-releasing hormone receptor

- Autoimmune inflammation 

14

What are the symptoms of GH hormone deficiency secondary to mass defects from a pituitary adenoma?

- Decreased tolerance to exercise

- Decreased muscle strength

- Increased body fat

- Reduced sense of “well-being"

15

Why is GH deficiency often difficult to diagnose?

GH secretion is pulsatile, deficiency is often difficult to diagnose and a combination of direct and indirect measurements are required

16

What are the symptoms of Gonadotropin deficiency in men and women secondary to mass defects from a pituitary adenoma?

- Women – infertility, oligomenorrhea, amenorrhea, lack of libido

- Men – impotence, lack of libido

17

What are some causes of ADH deficiency?

- Hypothalamic tumour

- Extension of pituitary tumour

- Cranial radiotherapy

- Pituitary surgery

- Autoimmune infiltration

- Infections e.g. meningitis

18

What is the main consequence of ADH deficiency?

Diabetes insipidus – excess excretion of dilute urine resulting in dehydration and an increased sensation of thirst (polydipsia)

19

What is hyperpituitarism?

Hyperpituitarism is a state of excess pituitary hormone production mainly due to a functional hypersecreting pituitary adenoma

20

There are three main conditions caused by excess pituitary hormone production from a hypersecreting pituitary adenoma.

Identify them 

- Prolactin excess

- Growth hormone access

- ACTH excess

21

Hyperprolactinaemia is the most common form of pituitary disorder and can cause a range of symptoms.

Identify five of these

- Galactorrhea (unexplained milk production – rare in men)

- Gynecomastia (hard breast tissue)

- Hypogonadism (diminished activity of testes or ovaries)

- Amenorrhea (cessation of menstrual cycle)

- Erectile dysfunction

22

What is the most common cause of hyperprolactinaemia?

Prolactinoma – a pituitary adenoma that secretes prolactin

23

Identify some physiological causes of hyperprolactinaemia

- Pregnancy

- Suckling

- Stress

- Exercise

- Drugs (antipsychotics & antidepressants)

24

In four steps, explain how hypogonadism arises as a co-morbidity in hyperprolactinaemia

⇒ Increased plasma prolactin

⇒ Higher level of dopamine for negative feddback 

⇒ Dopamine inhibits GnRH secretion from hypothalamus

FSH and LH secretion from the anterior pituitary inhibited

25

How is hyperprolactinaemia usually treated?

- Dopamine receptor agonists e.g. cabergoline

- Trans-sphenoidal surgery (rare)

- Radiotherapy (rare)

26

Growth hormone secreting pituitary adenomas are typically large (>10 mm in diameter).

In light of this, identify some of its associated symptoms

- Local mass effects – headache, visual field defects and other cranial nerve palsies

- Systemic effects – increased GH secretion & local IGF-1 production leads to gradual change in physical appearance

27

Describe some the the changes in physical characteristics observed in growth hormone excess

- Coarse facial features: broad nose, thick lips, prominent supraorbital ridge

- Enlargement of the hands and feet

- Greasy skin

- Excessive sweating

- Deepening of the voice (hypertrophy of vocal cords)

28

Explain why excess GH secretion can be associated with diabetes mellitus

GH antagonises the actions of insulin, so diabetes mellitus develops as a metabolic complication

29

Three types of treatment options are available for patients with acromegaly.

Identify them

- Surgery

- Radiation therapy

- Drug therapy e.g. dopamine receptor agonists, synthetic somatostatin analogs

30

What is a consequence of excessive ACTH secretion due to a pituitary adenoma?

Excess endogenous secretion of ACTH from the anterior pituitary gland is one of the causes of Cushing’s syndrome