Pituitary Physiology Flashcards Preview

The Endocrine System > Pituitary Physiology > Flashcards

Flashcards in Pituitary Physiology Deck (42)
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1

Which hormones can be produced by the anterior pituitary?

  1. ACTH
  2. TSH
  3. FSH
  4. LH
  5. PRL

2

Which hormones can be produced by the posterior pituitary?

  1. ADH
  2. Oxytocin

3

Describe how thyroxine can be produced with hypothalmic stimulation

  1. Stress stimulus on hypothalamus
  2. Thyrotropin releasing hormone released
  3. Anterior pituitary releases thyrotropin
  4. Thyroid releases thyroxine

4

What releases corticotropin releasing hormone?

Hypothalamus

5

What effects does corticotropin releasing hormone have?

Acts on the pituitary to cause ACTH release

6

Where does ACTH act and what is the result of this?

Adrenal gland

Cortisol release

7

Why is prolactin different to other hormones in terms of its release?

Its release is under constant suppression by dopamine

8

If the pituitary hormone is GH, what is the peripherally acting hormone?

IGF-1

(insulin-like growth factor)

9

If hormone levels appear high, which type of test will be used?

Suppression test

10

Why is it a worry if a hormone suppression test fails?

It may suggest a tumour causing autonomous hormone release

11

If there is too little hormone, which test would be used?

Stimulation test

12

Which hormones are tested in an insulin stress test?

  1. Cortisol
  2. GH

13

Describe an insulin stress test

Hypoglycaemia induced

Hormone (cortisol and GH) measured at 30 minute intervals for 2-3 hours

14

How can pituitary release of cortisol be tested?

Synacthen (synthetic ACTH) administered

Cortisol levels measured at 0, 30 and 60 minutes

15

Describe a water deprivation test

  1. Serum and urine osmolalities tested for 8 hours
  2. IM DDAVP (desmopressin - an anti-diuretic) is administered
  3. Serum and urine osmolalities tested for 4 hours
  4. If urine/serum osmolar ratio > 2 then this is normal, any less confirms Diabetes inspidus

16

How are pituitary tumours classified based on size?

= 1cm microadenoma

> 1cm macroadenoma

17

Which cranial nerves are potentially most impacted in a pituitary tumour?

CN 3, 4 and 6

18

What is bitemporal hemianopia?

Loss of peripheral vision

19

What causes bitemporal hemianopia?

  1. Nasal retinal fibres detect peripheral light
  2. These fibres cross over at the optic chiasm which can be compressed by a pituitary tumour
  3. Hence, peripheral vision is lost

20

What are the two main causes for prolactin increases?

  1. Physiological
  2. Drugs

21

What are the main physiological causes for prolactin increase?

  1. Breastfeeding
  2. Pregnancy
  3. Stress
  4. Sleep

22

Which types of drugs can cause increases in prolactin?

  1. Dopamine antagonists (metoclopramide)
  2. Antipsychotics
  3. Antidepressants
  4. Oestrogen, cocaine etc

23

What are the key pathological reasons as to why prolactin may increase?

  1. Hypothyroidism
  2. Stalk lesions (iatrogenic or RTA)
  3. Prolactinoma

24

How does the timing of presentation of a prolactinoma differ in males and females?

Males - Late presentation

Females - Early presentation

25

What are the symptoms of a prolactinoma in females?

  1. Menstrual irregularities/ammenorrhoea
  2. Galactorrhoea
  3. Infertility

26

What are the symptoms of a prolactinoma in males?

  1. Impotence
  2. Visual field problems
  3. Headache
  4. Antertior pituitary malfunction

27

What are the relevant investigations for a prolactinoma?

  1. Prolactin concentration
  2. MRI (size of tumour, pituitary stalk/optic chiasm damage)
  3. Visual field check
  4. Pituitary function tests

28

Dopamine agonists are treatment for prolactinoma, what is the most commonly used drug?

Cabergoline

29

What are the benefits of cabergoline in prolactinoma treatment?

  1. Least side effects compared with other drugs
  2. Normalises prolactin in 96%
  3. Can induce tumour shrinkage
  4. Pregnancy rates increase

30

Acromegaly is due to an excess in which hormone?

GH