Endocrine - Online MedEd - thyroid

Question 1

What does T4 do?

Answer 1

Movement
Mental
Metabolic active
*Can’t live without T4

Question 2

Excess of T4 does what?

Answer 2

Turn off TRH and TSH

Question 3

TSH inhibits…

Answer 3

TRH

Question 4

Hyperthyroid/thyroxicosis - symptoms

Answer 4

Tachycardia
Diarrhea
Heat intolerant (feels hot)
Increased DTR
Weight loss
Afib

Question 5

Screen hyperthyroid with

Answer 5

TSH, then confirm with free T4

Hyperthyroid, TSH will be low and T4 high

Question 6

First test of thyroid is always

Answer 6

TSH

Question 7

Central hyperthyroid - pathophys

Answer 7

Elevated TSH drives T4

Question 8

Know how to interpret Radioactive Iodine Uptake Scan (RAIU)

Answer 8

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

Question 9

Grave’s disease - presentation and diagnosis, treatment

Answer 9

Exophthalmos
Preorbital myxoedema
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

Question 10

Thyroid storm - presentation

Answer 10

Afib/Shock
Fever
Hypotensive
AMS - altered mental status

Question 11

Thyroid storm - treatment

Answer 11

IVF
Temperature under control
1) Propranolol - reduce autonomic symptoms
2) PTU or methimazole
3) Steroid - reduce conversion of T4 to T3

Question 12

Treatment of hyperthyroid

Answer 12

1) Medical
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

Question 13

Hypothyroid - symptoms

Answer 13

Bradycardia
Constipation
Cold intolerance - patient feels cold
Decreased DTRs
Weight gain

Question 14

Lab values for hypothyroid

Answer 14

TSH is high , T4 low

Unless central lesion, both low

Question 15

Treatment of hypothyroid

Answer 15

Levothyroxine

Question 16

Causes of hypothyroid

Answer 16

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

Question 17

Myxoedema coma - what is it?

Answer 17

1) Coma
2) Hypothermic
3) Hypotension (due to drop in weight)

Question 18

Treatment of myxedema coma

Answer 18

IVF
Blankets
IV T4/T3