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2ND YEAR SYSTEMS: Diabetes and Endocrinology > Clinical thyroid disease > Flashcards

Clinical thyroid disease Flashcards

1
Q

Primary thyroid disease affects which part of the hypothalamo-pituitary-thyroid axis

A

Thyroid gland itself

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2
Q

Secondary thyroid disease affects which part of the hypothalamo-pituitary-thyroid axis

A

The pituitary

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3
Q

What feedbacks and inhibits the release of TRH from the hypothalamus and TSH from the pituitary

A

T3 and T4

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4
Q

Symptoms of Hypothyroidism (10)

A 
Weight Gain
Lethargy
Feeling cold
Constipation
Heavy periods
Dry Skin/Hair
Bradycardia
Slow reflexes
Goitre
Severe – puffy face, large tongue, hoarseness, coma
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5
Q

Symptoms of Hyperthyroidism (10)

A 
Weight Loss
Anxiety/Irritability
Heat Intolerance
Bowel frequency
Light periods
Sweaty palms
Palipitations
Hyperreflexia/Tremors
Goitre
Thyroid eye symptoms/signs
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6
Q

In primary hypothyroidism what would you expect the levels of TSH and FT4 +FT3 to be like?

A

TSH => high

Free T4 + Free T3 => low

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7
Q

What is Subclinical hypothyroidism?

A

Earlier stage of hypothyroidism

Normal thyroxine levels

Slightly elevated TSH levels

No symptoms

It’s common for the condition to progress to full-blown hypothyroidism.

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8
Q

In secondary hypothyroidism what would you expect the levels of TSH and FT4 +FT3 to be like?

A

Low TSH (pituitary has been affected)

Low T4+T3 in blood as a result

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9
Q

What is the commonest endocrine condition after diabetes?

A

Hypothyroidism

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10
Q

Name 2 congenital causes of primary hypothyroidism (affecting the thyroid)

A

Developmental (agenesis/maldevelopment)

Dyshormonogenesis

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11
Q

How is primary hypothyroidism detected in babies in the UK

A

Through screening

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12
Q

Name 4 causes of acquired primary hypothyroidism

A

Autoimmune thyroid disease (commonest in UK)

Iatrogenic (surgery/operations, post -radioactive iodine, anti-thyroid drugs)

Chronic iodine deficiency (Commonest worldwide)

Post subacute thyroiditis - post partum thyroiditis

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13
Q

Causes of secondary/tertiary hypothyroidism

A

Pituitary / hypothalamic damage e.g

  • pituitary tumour
  • craniopharyngioma
  • post pituitary surgery or radiotherapy
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14
Q

If you have a functioning pituitary what will this mean with a diagnosis of hypothyroidism?

A

TSH will always be elevated due to absence of negative feedback from thyroid hormones (these are low)

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15
Q

What investigations are carried out to diagnose hypothyroidism?

A

Blood tests:

  • TSH/fT4
  • Autoantibodies (thyroid peroxidase antibodies)

FBC
Lipids

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16
Q

Treatment of hypothyroidism

A

Levothyroxine (T4) tablets mainly - 1 x daily for rest of life

Titration method of treatment - start on high dose then reduce by 25mcg if needed

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17
Q

What is the half life of T4?

A

The half life of T4 = 7 days

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18
Q

When are patients brought back to the clinic for follow up blood testing after starting hypothyroidism treatment?

A

test every 6-8 weeks until stable then get them back for annual testing of TSH

Will be able to see if patient is being compliant

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19
Q

If a patient has ischaemic heart disease or is >65 y/o how should they be treated for hypothyroidism

A

Start them at lower dose 25mcg and increase cautiously due to risk of precipitating angina (increases metabolic rate which puts more pressure on the heart)

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20
Q

What is Myxoedema coma

A

Severe hypothyroidism leading to coma

Very rare emergency

may need IV T3

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21
Q

Treatment for subclinical hypothyroidism

A

Repeat tests after 2-3 months for Thyroxide peroxidase antibodies (to see if they have positive result)

Consider thyroid hormone treatment if TSH >10

If TSH >5 + symptoms then trial therapy for 6 months
If no symptomatic improvement stop and do annual monitoring if TPO +

Risk of osteopenia and AF in overtreatment

Treat subclinical hypothyroidism if planning pregnancy (or pregnant)

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22
Q

Define Osteopenia

A

Reduced bone mass of lesser severity than osteoporosis

23
Q

How is Hypothyroidism treated during pregnancy

A

Increased Levothyroxine requirements during pregnancy (by about 25% - monitor closely). Aim to keep TSH in normal range <2.5 mU/l and FT4 in high normal range

Optimise treatment pre-conceptually

Inadequately treated hypothyroidism linked with increased foetal loss and Lower IQ

24
Q

Causes of Goitre (5)

A

Physiological - Puberty, Pregnancy

Autoimmune - Grave’s, Hashimoto’s

Thyroiditis - Acute or chronic

Iodine deficiency (endemic goitre)

Dyshormogenesis

25
Q

What is Hashimoto’s disease

A

destructive thyroiditis – eventually goes on to be hypothyroidism

26
Q

Types of Goitre (4)

A

Multinodular

Diffuse - colloid or simple

Cystic

Tumour - adenoma, carcinoma, lymphoma

Miscellaneous - sarcoidosis, TB

27
Q

Solitary nodule thyroid malignancy risk

A

5% chance of malignancy

increased risk if child, adult <30 or >60, previous head and neck irradiation, pain, cervical lymphadenopathy

28
Q

Investigations for solitary thyroid nodule (3)

A

FNA - classification

Thyroid function test - it could just be a hyperfunctioning nodule

USS - differentiate if benign or malignant

29
Q

From a FNA how is Thyroid cancer classified

A

Thy1 - inadequate

Th2 - benign

Thy5 - Cancer

30
Q

What are the 2 differentiations of thyroid cancer

A

Papillary and Follicular

31
Q

Discuss Papillary thyroid cancer

A

Commonest

Multifocal, local spread to lymph nodes

Good prognosis

32
Q

Discuss Follicular thyroid cancer

A

Usually a single lesion

Metastases to lung/bone

Good prognosis if resectable

33
Q

How is thyroid cancer managed initially

A

The main goal of thyroid cancer treatment is to get rid of all thyroid cells.

Near total thyroidectomy

After patient is given high dose of radioiodine (ablative)

Long term suppressive doses of thyroxine - depending on the cancer stage

34
Q

What results in a poorer prognosis for thyroid cancer diagnosis

A

Age <16 or >45

Tumour size

Spread outside the thryoid capsule and metastases

TNM stage

35
Q

Follow up management for thyroid cancer

A

Thyroglobulin => replaces levels in blood after thyroidectomy + radioiodine

Whole body iodine scanning (following 2-4 weeks of thyroxine withdrawal or recombinant TSH injections)

36
Q

Anaplastic thyroid cancer

A

<5% of thyroid cancers

aggressive, locally invasive

very poor prognosis - doesn’t respond to radioiodine

37
Q

Lymphoma thyroid cancer

A

Rare

May arise from preexisting hashimotos thyroiditis

External RT more helpful, combined with chemotherapy

38
Q

Medullary thyroid cancer

A

Tumour arises from parafollicular C cells

Oftern associated with MEN 2 (phaeochromocytoma = hyperparathyroidism)

Treatment - total thyroidectomy - no role for radioiodine

39
Q

In Hyperthyroidism what would you expect the levels of TSH and FT4 +FT3 to be like?

A

TSH low/suppressed

T3/T4 high

40
Q

Causes of thyrotoxicosis

A

Primary - Grave’s, Toxic multinodular goitre, toxic adenoma

Secondary - pituitary adenoma secreting TSH

Thyrotoxicosis without hyperthyroidism - destructive thyroiditis, excessive thyroxine administration

41
Q

What is thyrotoxicosis

A

Hyperthyroidism is the condition that occurs due to excessive production of thyroid hormones by the thyroid gland.

Thyrotoxicosis is the condition that occurs due to excessive thyroid hormone of any cause and therefore includes hyperthyroidism.

42
Q

What is Grave’s disease

A

Cause of 70-80% of all hyperthyroidism cases

Autoimmune driven condition

thyroid peroxidase Antibodies

TSH receptor Antibodies

43
Q

What is the most common cause of thyrotoxicosis in the elderly?

A

Multi-nodular goitre

44
Q

Subacute (de Quervain’s thyroiditis)

A

Generally younger patient <50

Viral trigger (enteroviruses)

Often recall painful goitre +/- fever/myalgia

erythrocyte sedimentation rate - inflammation

May require short term steroids and NSAIDs

Patient will have a few weeks of thryotoxicosis and then months of hypothyroidism

45
Q

Management of hyperthyroidism

A

3 possible treatments

Radioiodine
Surgery
Drugs

46
Q

What can be used to help with side effects of the treatments of hyperthyroidism

A

Beta blockers - they slow things down

if contraindicated then sometimes use Ca2+ channel blockers

47
Q

What is the main antithyroid drug used in the treatment of hyperthyroidism

A

Carbimazole

48
Q

Which drug is used for hyperthyroidism during pregnancy

A

Propylthiouracil - not used otherwise due to risk of liver toxicity

49
Q

Treatment regime for hyperthyroidism

A

Titration – starting high and then progressively decreasing dose – this method is used more often now as it has fewer side effects. (12-18 months)

Block-replace = give a block of high dose then replace with thyroxine

50
Q

Radioiodine in treatment of hyperthyroidism

A

Can either be given in high dose ablative (more common) or variable calculated

There is a % risk of hypothyroidism after both methods

51
Q

What are used to reduce the risk of thyroid eye disease due to radioiodine?

A

Steroids

52
Q

When should radioiodine not be given

A

Pregnant women
Children under 18
Severe pre-existing eye disease

53
Q

In Subclinical hyperthyroidism what would you expect the levels of TSH and FT4 +FT3 to be like?

A

TSH suppressed

Normal free thyroid hormones

the body perceives you as being in hyperthyroid state so switches off TSH but you aren’t yet

54
Q

When is treatment for subclinical hyperthyroidism considered?

A

If it is persistent especially in elderly or those with increased cardiac risk

treatment = ATD or RAI

2ND YEAR SYSTEMS: Diabetes and Endocrinology (21 decks)

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