[37] Acquired Hypothyroidism Flashcards

1
Q

Is acquired hypothyroidism common?

A

Relatively

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2
Q

What is acquired hypothyroidism?

A

A condition where the thyroid gland makes insufficient thyroid hormone

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3
Q

What is primary hypothyroidism due to?

A

Inadequate function of the gland itself

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4
Q

What is secondary hypothyroidism due to?

A

A problem upstream of the thyroid gland

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5
Q

What problems upstream of the thyroid gland can cause secondary hypothyroidism?

A
  • Inadequate stimulation by TSH from the pituitary gland

- Inadequate release of thyrotropin-releasing hormone from the brain’s hypothalamus

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6
Q

How much more common is primary hypothyroidism than secondary hypothyroidism?

A

1000x

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7
Q

What are the causes of primary hypothyroidism?

A
  • Autoimmune
  • Iodine deficiency
  • Subacute thyroiditis
  • Drugs
  • Post-irradiation
  • Post-ablative
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8
Q

What are the autoimmune causes of primary hypothyroidism?

A
  • Hashimoto’s

- Chronic lymphocytic thyroiditis

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9
Q

Give two examples of drugs that can cause hypothyroidism

A
  • Amiodarone

- Lithium

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10
Q

Give two causes of ablative hypothyroidism

A
  • Radioiodine therapy

- Surgery

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11
Q

What will be found on blood tests in central hypothyroidism?

A
  • Low serum TSH

- Low T4

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12
Q

What are the causes of central hypothyroidism?

A
  • Intracranial tumour/mass
  • Post cranial radiotherapy/surgery
  • Developmental pituitary defects
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13
Q

What is the problem with the diagnosis of acquired hypothyroidism?

A

The symptoms and signs and usually insidious, and can be extremely difficult to diagnose clinically

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14
Q

What is the result of the signs and symptoms of acquired hypothyroidism usually appearing insidiously?

A

A high index of suspicion is required

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15
Q

What are the symptoms of acquired hypothyroidism?

A
  • Dry skin
  • Constipation
  • Delayed puberty/amennorhoea
  • Poor concentration and deterioration in school work
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16
Q

What are the signs of acquired hypothyroidism?

A
  • Cold intolerance
  • Thin, dry hair
  • Bradycardia
  • Cold peripheries
  • Goitre
  • Slow-relaxing reflexes
  • Slipped upper femoral epiphysis
  • Short stature/poor growth
17
Q

What investigations should be done in acquired hypothyroidism?

A
  • Thyroid function tests

- Thyroid antibody screen

18
Q

What might the thyroid antibody screen show in acquired hypothyroidism?

A

Raised antibody titres for;

  • Anti-thyroid peroxidase
  • Anti-thyroglobulin
  • TSH receptor (blocking type)
19
Q

What are the differential diagnoses for acquired hypothyroidism?

A
  • Other causes of short stature
  • Other causes of fall-off in growth
  • Other causes of goitre
20
Q

How is acquired hypothyroidism managed?

A

Oral levothyroxine 25-200micrograms/day

21
Q

What monitoring is required in acquired hypothyroidism?

A

Need to monitor TFTs every 4-6 months during childhood, and monitor growth and neurodevelopment

22
Q

What are the complications of acquired hypothyroidism?

A

Increased risk of developing other autoimmune disorders, e.g. vitiligo, RA