Chemical pathology 8 - Thyroid Flashcards Preview

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Flashcards in Chemical pathology 8 - Thyroid Deck (16)
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1

What % of T4 is typically bound to TBG?

75%

2

To which proteins can T4 bind?

TBG
TBPA
Albumin

3

Recall the possible aetiologies of primary hypothyroidism

Mnemonic: Hypothyroidism Possible Aetiology
Main causes are:
H = Hashimoto's
P = Post-Grave's disease
A = Atrophic
Other causes (more rare):
Drugs (eg lithium)
Thyroid dysgenesis
Peripheral T3 resistance

4

What is the expected TSH and T4 levels in primary hypothyroidism?

TSH high
T4 low

5

What test should always be done before thyroid-replacement medication is initiated?

ECG - because T4 increases cardiac contractility

6

How does thyroid function change in pregnancy?

In 1st trimester, there is a huse rise in hCG
hCG has the same configuration as TSH - this then stimulates the thyroid gland to produce supra-physiological amounts of thyroxine
However, this is normal in pregnancy, so the woman doesn't become clinically hyperthyroid

7

What type of non-thyroid malignancy can cause thyrotoxicosis?

Malignancy that produces hCG

8

What test is used to detect neonatal hypothyroidism?

Guthrie test on day 2/3 of life

9

What does the term 'sick euthyroid' refer to?

Any severe illness --> reduced T4, increased TSH and decreased T3
This is normal physiology in sepsis

10

Recall 5 differentials for the cause of hyperthyroidism, and how each would appear on a technetium scan

1. Grave's (40-60% of cases) - high uptake
2. Toxic multinodular goitre - high uptake
3. Single toxic adenoma - high uptake
4. Subacute thyroiditis - low uptake
5. Postpartum thyroiditis - low uptake

11

What drugs can be used to treat an overactive thyroid? What is their mechanism of action?

Carbimazole and propylthiouracil
Inhibit TPO

12

What is the main risk of carbimazole and propylthiouracil treatment?

Agranulocytosis

13

Over how long should carbimazole and propylthiouracil treatment be titrated ?

18 months

14

How should papillary thyroid Ca be treated?

Removal of thyroid gland
Then radioiodine treatment
Then give supraphysiological thyroxine (so Ca cells not reactivated)

15

Recall 2 tumour markers for medullary thyroid cancer

CEA and calcitonin

16

Which type of thyroid cancer is associated with Men II?

Medullary

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