Flashcards in Endocrine - Online MedEd - thyroid Deck (18):
What does T4 do?
*Can't live without T4
Excess of T4 does what?
Turn off TRH and TSH
Hyperthyroid/thyroxicosis - symptoms
Heat intolerant (feels hot)
Screen hyperthyroid with
TSH, then confirm with free T4
Hyperthyroid, TSH will be low and T4 high
First test of thyroid is always
Central hyperthyroid - pathophys
Elevated TSH drives T4
Know how to interpret Radioactive Iodine Uptake Scan (RAIU)
1) Graves disease - normal thyroid, TSH antibodies are made that activate TSH receptors --> thyroid gets bigger - whole thyroid will light up (TSH receptors everywhere on thyroid)
2) Thyroiditis - preformed T4, some iditis causes thyroid to fracture so now 2 thyroids --> cause transient hypothyroid state --> either thyroid will heal or shrivel up and die --> hashimotos. So in thyroiditis, won't light up on scan
3) Multinodular goiter --> many little lesions are secreting T4, will light up
4) Toxic adenoma --> one big lesion secreting T4, will light up
5) Factitious - exogenous T4 ingested
6) Stroma ovarii - ovarian lesion producing T4, will have a cold thyroid. will need a sestamibi scan of ovaries
Grave's disease - presentation and diagnosis, treatment
Dx: Thyroid stimulating antibodies
Treatment: responds well to medical therapy, PTU and methimazole. Can use radioactive iodine ablation.
But if have exophthalmos and preorbital myxoedema, will need steroid and surgery because medical therapy can worsen
Thyroid storm - presentation
AMS - altered mental status
Thyroid storm - treatment
Temperature under control
1) Propranolol - reduce autonomic symptoms
2) PTU or methimazole
3) Steroid - reduce conversion of T4 to T3
Treatment of hyperthyroid
2) Surgery - generally for Graves disease as radioactive iodine can cause exophthalmos etc.
3) Radioactive iodine - for multi nodular loiter, toxic adenoma, stroma ovarii
*Surgery and radioactive iodine are definitive treatment, whereas medical is to control symptoms
Hypothyroid - symptoms
Cold intolerance - patient feels cold
Lab values for hypothyroid
TSH is high , T4 low
(Unless central lesion, both low)
Treatment of hypothyroid
Causes of hypothyroid
1) Iatrogenic - treated Graves
2) Hashimoto's - get TPO antibodies to confirm
*Doesn't matter too much about cause because same tx...except in...
3) Subclinical hypothyroid - treat if there are symptoms of hypothyroid
Myxoedema coma - what is it?
3) Hypotension (due to drop in weight)