Lecture 2 - Investigation of endocrine disease Flashcards Preview

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Flashcards in Lecture 2 - Investigation of endocrine disease Deck (27):
1

What are the 3 types of hormone?

Peptide - PCTH, TSH

Steroid - Testosterone, oestradiol, cortisol

Thyroid Based Hormone TSH, T3, T4

2

What hormone does the thymus secrete?

Thymosin - Incr T cell production

3

What hormone does the GI tract secrete?

Grelin. Regulates hunger

4

What hormone does the heart secrete?

BNP - response to stress

5

Give a generic overview of the feedback regulation system

Hypothalamus signals to anterior pituitary

Anterior pituitary releases stimulated hormone to endocrine organ

Endocrine organ releases hormone.

Hormone negatively feedback to anterior pituitary + hypothalamus, switching them off

6

Describe the Hypothalamic-Pituitary-Adrenal axis

o Stress stimulus in amygdala hypothalamus produces CRF
o CRF acts on pituitary gland ACTH released into blood
o ACTH acts on adrenal glands cortisol released stress response
o Cortisol negative feedbacks to pituitary, hypothalamus + amygdala to stop stimulation to produce cortisol

7

What's the difference between a primary and secondary endocrine problem?

Primary - problem with the gland itself

Secondary - problem with the pituitary

8

What are the 2 causes of excessive cortisol production?

Primary problem - adrenal gland overproduces cortisol.

Test - low ACTH, high cortisol

Secondary problem - pituitary overstimulating adrenal glands
Test - high ACTH, high cortisol

9

What else could cause overproduction of cortisol?

Ectopic ACTH - could be caused by tumours of the:
Lung
Islet cell tumour in pancreas
Tumours of the thymus gland

10

What are the 2 causes of insufficient cortisol production?

Primary - hypothalamus is fine but adrenal gland not responding.
Test - High ACTH, low cortisol

Secondary - pituitary not producing ACTH, so low cortisol

11

What could cause secondary cortisol insufficiency

Taking steroids - bc blood cortisol is always high, body stops producing ACTH. When you stop taking steroids, body loses ability to regulate

12

Test for Cushing's (e.g. hypercortisol)

Suppression test - give dexamethasone (steroid - should suppress ACTH)
If steroid doesn't suppress ACTH, it tells you you have too much, but doesn't tell you if its a primary or secondary problem

Measure ACTH levels on day 1. Give dexamethasone and check ACTH levels on day 2 at 9am. If not less than <50nmol/L

13

Test for Addison's (hypocortisol)

Stimulation test - synacthen test. Give ACTH, should cause incr in cortisol.

Measure at 9am

14

Hypothyroidism - what would the test results be for primary/ secondary hypothyroidism

Primary - TSH high, T3/4 low

Secondary - TSH low, T3/4 low

15

Hyperthyroidism - what would the test results be for primary/ secondary hyperthyroidism

Primary - low TSH, high T3/4

Secondary - high TSH, high T3/4

16

What is euthyroid disease?

People don’t have thyroid disease, but have shock, inflammation, infection + cytokine production. Inflammation response.

Cytokines act on hypothalamus – prevents iodine uptake into thyroid cells

Prevents thyroperoxidase activity which makes thyroid hormones

17

Test for euthyroid?

Low T4/3, no TSH

18

What effects hormonal release?

Annual cycles – hair growth

Monthly cycles – menses

Diurnal – cortisol

Rapid amplitude cycles – insulin

Stress related – anterior pituitary hormones

Stimulus related – insulin

19

When should you take a urine sample?

When you have pulsatile secretion (peaks and troughs in secretion)

Analysis fo unstable hormones that break down in the blood

When you want to avoid venipuncture

20

What to look for in pheochromocytoma urine test?

Measure metanephrine + normetanephrine in urine (what catecholamines get broken down into)

21

Clinical features of phaeochromocytoma

Hypertension
Sweating/ pallor
Abdo pain
Headaches

22

Follow up test for phaeochromocytoma

Clonidine suppression test

23

What is an insulinoma + what is it's presentation?

Tumour of the pancreas

Secretes excess insulin

Presents as hypoglycaemic symptoms

24

Test for insulinoma?

Give IV insulin + measure C-peptide.

Exogenous insulin suppresses C-peptide, but it won’t in an insulinoma.

25

Signs and Symptoms of hypoglycaemia

TIRED
Tachycardia
Irritability
Restless
Excessive hunger
Depression/ diaphoresis (sweating

26

Measuring thyroid in the blood

Free hormones are functional

When bound to TBG - inactivated

Immunoassay - take blood test to see how much free t3/4 there is

27

What is the problem with measuring thyroid in the blood?

Excess binding protein binds to T3/4 making it seem like there's less than there is.