LMP301 Lecture 8: Thyroid Disease Flashcards Preview

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Flashcards in LMP301 Lecture 8: Thyroid Disease Deck (82)
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1

What is symptom of goiter?

Enlarged thyroid gland

2

Is goiter due to hypo, hyper, or eu-thyroid?

Can be anything

3

Goiter is due to...

Lack of iodine

4

Thyroid gland secretes...

T3 and T4

5

What is more abundant in the blood, T3 or T4?

T4

6

What makes 2/3 of the circulating T3?

Peripheral tissues (liver, kidney) deiodinate T4

7

What stimulates the production of thyroid hormones?

TSH

8

What is more biologically active, T3 or T4?

T3

9

What is the inactive form of T3?

rT3 (reverse)

10

How is rT3 produced

metabolised from T4
(T4 can make both T3 and rT3)

11

How can local thyroid status be modulated?

Balance production of T3 and rT3

12

Thyroid hormones are needed for...

all tissue maturation and metabolism

13

Precursor for thyroid hormones

tyrosine

14

MIT structure

1 iodide attached to tyrosine

15

DIT structure

2 iodides attached to tyrosine

16

T4 is made up of

DIT + DIT

17

T3 is made up of...

MIT + DIT
T4 - 1 iodine (at first benzene)

18

rT3 is made up of...

T4 - 1 iodine (at second benzene)

19

T4 is also called...

thyroxine

20

Hypothalamus-pituitary-thyroid axis for T3, T4 control

Hypothalamus: TRH
a. pituitary: TSH
Thyroid: TSH binds on TSH receptor -> T4 and T3 production

21

Feedback of thyroid hormones

TSH neg feedback on hypothalamus (short loop feedback)

T4 + T3 neg feedback on hypothalamus, a. pituitary (long loop feedback)

22

How do thyroid hormones travel? Give some examples.

Bound to carrier proteins in plasma (e.g. albumin, TBG)

23

TBG

T4-binding globulin

24

Which thyroid hormones are active?

The ones not bounded to carrier proteins in the plasma

25

% of free T3 + T4

T3: 0.3% of all T3
T4: 0.03% of all T4

26

What may change the concentration of free thyroid hormones?

Changes in the [ ] or affinity of carrier proteins

27

Are FT3 + FT4 better or worse markers of thyroid function? Why?

Better

28

Effects of increasing TBG

More T4 + T3
Same FT4
Same TSH

29

What compounds increase TBG?

- estrogen
- oral contraceptives

30

Effects of decreasing TBG

Less T4 + T3
Same FT4
Same TSH