Flashcards in Chemical pathology 8 - Thyroid Deck (16)
What % of T4 is typically bound to TBG?
To which proteins can T4 bind?
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)
Peripheral T3 resistance
What is the expected TSH and T4 levels in primary hypothyroidism?
What test should always be done before thyroid-replacement medication is initiated?
ECG - because T4 increases cardiac contractility
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
What type of non-thyroid malignancy can cause thyrotoxicosis?
Malignancy that produces hCG
What test is used to detect neonatal hypothyroidism?
Guthrie test on day 2/3 of life
What does the term 'sick euthyroid' refer to?
Any severe illness --> reduced T4, increased TSH and decreased T3
This is normal physiology in sepsis
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
What drugs can be used to treat an overactive thyroid? What is their mechanism of action?
Carbimazole and propylthiouracil
What is the main risk of carbimazole and propylthiouracil treatment?
Over how long should carbimazole and propylthiouracil treatment be titrated ?
How should papillary thyroid Ca be treated?
Removal of thyroid gland
Then radioiodine treatment
Then give supraphysiological thyroxine (so Ca cells not reactivated)
Recall 2 tumour markers for medullary thyroid cancer
CEA and calcitonin