Hypothyroidism

Question 1

Epidemiology

Answer 1

Incidence: 4/1000/yr
Sex: F»M=6:1
Age: >40yrs

Question 2

Symptoms

Answer 2

Lethargy
  Cold intolerance
  ↓ appetite but ↑wt.
  Constipation
  Menorrhagia
  ↓mood

Question 3

Signs

Answer 3

Cold hands
  Bradycardic
  Slow-relaxing reflexes
  Dry hair and skin
  Puffy face
  Goitre
  Myopathy, neuropathy
  Ascites
  Myxoedema
  SC tissue swelling in severe hypothyroidism   Typically around eyes and dorsum of hand

Question 4

Primary causes

Answer 4

Atrophic thyroiditis (commonest UK)
Hashimoto’s thyroiditis
Subacute thyroiditis (e.g. post-partum)
Post De Quervain’s thyroiditis
Iodine deficiency (commonest worldwide)
Drugs: carbimazole, amiodarone, lithium
Congenital: thyroid agenesis

Question 5

Post-surgical causes

Answer 5

Thyroidectomy

Radioiodine

Question 6

Secondary causes

Answer 6

Hypopituitarism (v. rare cause)

Question 7

What is atrophic thyroiditis

Answer 7

Thyroid antibodies +ve: anti-TPO, anti-TSH
Lymphocytic infiltrate → atrophy (no goitre)

Associations:
Pernicious anaemia Vitiligo
Endocrinopathies

Question 8

What is hashimoto’s thyroiditis

Answer 8

TPO +ve
Atrophy + regeneration → goitre
May go through initial thyrotoxicosis phase
May be euthyroid or hypothyoid

Question 9

Investigations and results

Answer 9

↑TSH, ↓T3/T4
  ↑MCV ± normochromic anaemia   ↑ triglyceride + ↑ cholesterol
  Hyponatraemia (SIADH)
  ↑ CK if assoc. myopathy
  Abs: TPO, TSH

Question 10

Treatment

Answer 10

Rx
Levothyroxine
Titrate to normalise TSH
Enzyme inducers ↑ thyroxine metabolism Clinical improvement takes ~2wks
Check for other AI disease: e.g. Addison’s, PA

Question 11

Features of a myxoedema coma

Answer 11

Looks hypothyroid
Hypothermia
Hypoglycaemia
Heart failure: bradycardia and ↓BP Coma and seizures

Question 12

Precipitants

Answer 12

Radioiodine
Thyroidectomy
Pituitary surgery
Infection, trauma, MI, stroke

Question 13

Management

Answer 13

Bloods: TFTs, FBC, U+E, glucose, cortisol
Correct any hypoglycaemia
T3/T4 IV slowly (may ppt. myocardial ischaemia)
Hydrocortisone 100mg IV
Rx hypothermia and heart failure

Question 14

What is congenital hypothyroidism

Answer 14

If not diagnosed and treated within the first four weeks it causes irreversible cognitive impairment

Question 15

Features

Answer 15

Features
prolonged neonatal jaundice
delayed mental & physical milestones
short stature
puffy face, macroglossia
hypotonia

Question 16

When is Cong hypo checked for

Answer 16

Children are screened at 5-7 days using the heel prick test