Chempath - Thyroid

Question 1

High TSH, Low T4?

Answer 1

Primary hypothyroidism

Question 2

High TSH, normal T4?

Answer 2

Treated hypothyroidism or subclinical hypothyroidism

Question 3

High TSH, high T4?

Answer 3

TSH secreting tumour

Question 4

Low TSH, High T4

Answer 4

Primary hyperthyroidism

Question 5

Low TSH normal T4

Answer 5

subclinical hyperthyroidism

Question 6

Low TSH, low T4

Answer 6

central hypothyroidism

Question 7

Initially high TSH then low TSH, low T3, low T4

Answer 7

Sick euthyroidism

Question 8

Normal thyroxine hormone synthesis?

Answer 8

1. iodine absorbed from GIT and converted to I-
2. I- is taken up by thyroid cells
3. I- –>I2 by TPO
4. I2 is taken up by thyroglobulin
5. Converted to MIT, DIT, T3 and T4
6. T3 and T4 are transported to capillary lumen

Question 9

T3 and T4 - how does it travel in the circulation?

Answer 9

Bound mostly to proteins - TBG, TBPA and albumin

0.03% is free and active!

Question 10

Top 3 causes of hypothyroidism?

Answer 10

1. Primary atrophic hypothyroidism
2. Hashimoto’s thryoiditis
3. Post thyroidectomy/radioiodine

Question 11

Hashimoto’s thyroiditis - what is it? epidemi?

Answer 11

• anti-TPO antibodies –> goitre + plasma cell infiltration of thyroid
• Elderly females.

Question 12

Drugs which induce hypothyroidism?

Answer 12

PTU/CBZ
Lithium
AMiodarone

Question 13

WTF is subclinical hypothyroidism

Answer 13

High TSH and normal T4 (body wrongly thinks T4 levels are low)
Predictor for future primary hypothyroidism, esp if anti-TPO is present

Question 14

WTF is sick euthyroidism? presentation?

Answer 14

A physiological response to severe illness - the thyroid shuts down to reduce basal metabolic rate
Asymptomatic

Question 15

Ix done in suspected hypothyroidism?

Answer 15

TFTs
anti-thyroid antibodies
ECG - as tx can cause MI
Screen for other autoimmune conditions

Question 16

Tx for hypothyroidism? precautions?

Answer 16

Levothyroxine (dose depends on weight)

Must do ECG (excess T4 = risk of AFib and osteopenia)

Question 17

top 3 causes of hyperthyroidism?

Answer 17

1) Graves disease
2) toxic multi nodular goitre
3) toxic adenoma

Question 18

Graves disease - M/F? what type of hyperthyroidism? Cause? presentation?

Answer 18

F:M is 9:1!
High uptake on technetium scan
Anti-TSHR and anti-TPO
Wt loss, diarrhoea, dysmenorrhea, tremor
Exophthalmos, pretibial myxoedema, acropachy

Question 19

3 causes of high uptake hyperthyroidsm

Answer 19

1) Graves disease
2) toxic multi nodular goitre
3) toxic adenoma

Question 20

2 causes of low uptake hyperthyroidism

Answer 20

1) subacute dequiervan’s thyroiditis

2) post partum thyroiditis

Question 21

Features of subacute dequervain’s thyroiditis.

TFTs?

Answer 21

Post-viral
Painful goitre!!!
Initially hyperthyroid, then hypothyroid

Question 22

Important Ix in suspected hyperthyroidism

Answer 22

TFTs
Technetium scan
Anti-thyroid antibodies
Screen for autoimmune antibodies
ECG for concurrent AFib
Bone mineral density

Question 23

Treatment for high uptake hyperthyroidism?

Answer 23

Beta blockers
CBZ or PTU = to block and replace, or titrate
Consider radio iodine and surgery

Question 24

When not to use radio iodine?

Answer 24

If Graves disease with exophthalmos, radio-iodine can make things worse!!

Question 25

Treatment for low uptake hyperthyroidism?

Answer 25

Beta blockers

NSAIDs for De Quervain’s thyroiditis

Question 26

Precautions with PTU and Carbimazole?

Answer 26

1% develop agranulocytosis
warn patients to seek HCP if fever/sore throat
Titrate dose for 18 months

Question 27

3 types of thyroid cancer? most common?

Answer 27

Papillary - most common
Follicular
Medullary

Question 28

Histology and prognosis for most common type of thyroid cancer?

Answer 28

Papillary thyroid cancer

• Psammoma bodies
• v good prognosis!

Question 29

mx of thyroid cancer

Answer 29

Surgery (thyroidectomy)
+/- Radioiodine
Thyroxine (to suppress TSH)

Question 30

Medullary thyroid cancer

• what is it linked to?
• which Ix must you do

Answer 30

linked to MEN2 (phaeo + parathyroid cancer)

- calcitonin and CEA levels