Chempath - Thyroid Flashcards

1
Q

High TSH, Low T4?

A

Primary hypothyroidism

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2
Q

High TSH, normal T4?

A

Treated hypothyroidism or subclinical hypothyroidism

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3
Q

High TSH, high T4?

A

TSH secreting tumour

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4
Q

Low TSH, High T4

A

Primary hyperthyroidism

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5
Q

Low TSH normal T4

A

subclinical hyperthyroidism

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6
Q

Low TSH, low T4

A

central hypothyroidism

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7
Q

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

A

Sick euthyroidism

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8
Q

Normal thyroxine hormone synthesis?

A
  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
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9
Q

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

A

Bound mostly to proteins - TBG, TBPA and albumin

0.03% is free and active!

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10
Q

Top 3 causes of hypothyroidism?

A
  1. Primary atrophic hypothyroidism
  2. Hashimoto’s thryoiditis
  3. Post thyroidectomy/radioiodine
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11
Q

Hashimoto’s thyroiditis - what is it? epidemi?

A
  • anti-TPO antibodies –> goitre + plasma cell infiltration of thyroid
  • Elderly females.
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12
Q

Drugs which induce hypothyroidism?

A

PTU/CBZ
Lithium
AMiodarone

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13
Q

WTF is subclinical hypothyroidism

A

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

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14
Q

WTF is sick euthyroidism? presentation?

A

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

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15
Q

Ix done in suspected hypothyroidism?

A

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

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16
Q

Tx for hypothyroidism? precautions?

A

Levothyroxine (dose depends on weight)

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

17
Q

top 3 causes of hyperthyroidism?

A

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

18
Q

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

A
F:M is 9:1!
High uptake on technetium scan
Anti-TSHR and anti-TPO
Wt loss, diarrhoea, dysmenorrhea, tremor
Exophthalmos, pretibial myxoedema, acropachy
19
Q

3 causes of high uptake hyperthyroidsm

A

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

20
Q

2 causes of low uptake hyperthyroidism

A

1) subacute dequiervan’s thyroiditis

2) post partum thyroiditis

21
Q

Features of subacute dequervain’s thyroiditis.

TFTs?

A

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

22
Q

Important Ix in suspected hyperthyroidism

A
TFTs
Technetium scan
Anti-thyroid antibodies
Screen for autoimmune antibodies
ECG for concurrent AFib
Bone mineral density
23
Q

Treatment for high uptake hyperthyroidism?

A

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

24
Q

When not to use radio iodine?

A

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

25
Q

Treatment for low uptake hyperthyroidism?

A

Beta blockers

NSAIDs for De Quervain’s thyroiditis

26
Q

Precautions with PTU and Carbimazole?

A

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

27
Q

3 types of thyroid cancer? most common?

A

Papillary - most common
Follicular
Medullary

28
Q

Histology and prognosis for most common type of thyroid cancer?

A

Papillary thyroid cancer

  • Psammoma bodies
  • v good prognosis!
29
Q

mx of thyroid cancer

A

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

30
Q

Medullary thyroid cancer

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

linked to MEN2 (phaeo + parathyroid cancer)

- calcitonin and CEA levels