Hypothyroidism Flashcards

1
Q

outline the typical presentation of hypothyroidism?

A

Hashimotos: cold intolerance, weight gain, C, dry skin, hair loss, hoarseness, mental slowness, depression, irreg cycles, firm diffuse goitre - anti-TPO, anti-tG, AMA - can cause non-megaloblastic anaemia - associated with Non-hodgkin’s lymphoma MAY BE EASILY CONFUSED AS ALZHEIMER’S Myxoedema coma: hypoventilating, hypothermia, hyponatremia, confusion, coma, HF

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2
Q

define hypothyroidism?

A

Clinical syndrome resulting from insufficiency of thyroid hormones

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3
Q

what are the risk factors for hypothyroidism?

A

iodine deficiency

female sex

middle age

family history of autoimmune thyroiditis

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4
Q

what are the causes of acquired primary hypothyroidism?

A

PRIMARY= DECREASED THYROID HORMONE PRODUCTION

Hashimoto’s thyroiditis (autoimmune)

Iatrogenic (post-surgery, radioiodine, hyperthyroid medication, amiodarone or lithium)

Severe iodine deficiency – poor diet in “developing” countries

Iodine excess (Wolff-Chaikoff effect)

Thyroiditis

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5
Q

what are the causes of congenital primary hypothyroidism?

A

Thyroid dysgenesis

Inherited defects in thyroid hormone biosynthesis

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6
Q

what are the causes of secondary hypothryoidism?

A

Pituitary and Hypothalamic Disease - resulting in reduced TSH and TRH and, hence, reduced stimulation of thyroid hormone production

‘Subclinical’ hypothyroidism describes a normal serum T4 with an elevated serum TSH.

Primary myxoedema ( spontaneous atrophic hypothyroidism): idiopathic reduction in the production of thyroid hormones with no goitre

Sick euthyroid syndrome is the presence of low TSH, T3 and/or T4 but with a normal functioning thyroid. It is often seen during a period of illness but recovers when the illness is over. Treatment is supportive.

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7
Q

what is the epidemiology of hypothyroidism?

A

0.1-2% of adults

6 x more common in FEMALES

Most common age of onset > 40 yrs

Iodine deficiency is seen in mountainous areas (e.g. Himalayas)

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8
Q

what are the symptoms of hypothyroidism?

A

INSIDIOUS onset

Cold intolerance –> Erythema ab igne

Lethargy

Weight gain

Reduced appetite

Constipation

Dry skin

Hair loss

Hoarse voice

Mental slowness

Depression

Cramps

Ataxia

Paraesthesia

Menstrual disturbance (irregular cycles, menorrhagia), loss of libidoetc – due to prolactinaemia – get in primary hypothyroidism as increased levels of TRH causes more prolactin release

History of surgery or radioiodine therapy for hyperthyroidism

Personal/family history of other autoimmune conditions (e.g. Addison’s, type 1 diabetes mellitus)

Myxoedema coma (severe hypothyroidism usually seen in the elderly):

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9
Q

what are the features of a myxoedema coma?

A

Hypothermia

Hypoventilation

Hyponatraemia

Heart failure

Confusion - Disorientation in time and place is typical.

Coma

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10
Q

what are the signs of hypothyroidism?

A

Hands

  • Bradycardia
  • Cold hands

Head/Neck/Skin

  • Pale puffy face
  • Goitre
  • Oedema
  • Hair loss
  • Dry skin
  • Vitiligo

Chest

  • Pericardial effusion
  • Pleural effusion

Abdomen

  • Ascites

Neurological

  • Slow relaxation of reflexes
  • Signs of carpal tunnel syndrome
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11
Q

outline the investigations for hypothyroidism?

A
  • serum TSH- elevated
  • serum T4- low
  • May look for autoantibodies after TFTs are abnormal
  • FBC - may show normocytic anaemia - as everything slows down so much and so does the BM production essentially/ can cause non-megaloblastic macrocytic anaemia
  • U&Es - may show low sodium
  • Cholesterol - may be high
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12
Q

what is the key investigation for hypothyroidism?

A

serum TSH- low

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13
Q

what is the management for chronic hypothyroidism?

A

Levothyroxine (25-200 mcg/day)

Average dosage is 125 mcg/d-> adjust dose based on clinical picture and TFTs (aim for a fT4 in upper limits without suppressing TSH)

Symptomatic improvement seen within two weeks of initiating thyroxine therapy. It may take up to six weeks of full treatment for TSH levels to normalise

Elderly pts & pts with IHD should be introduced gradually as -> precipitate in angina and palpitations - titration in small increments every 6 weeks to therapeutic dose and monitor for ischaemic symptoms

Have a blood test (TSH looked at mainly) atleast once a year to check compliance and adequacy of treatment

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14
Q

what should you rule out before starting thryoid hormone replacement?

A

adrenal insufficiency- > can precipitate addisonian crisis

thyroid hormones increase clearance of glucucorticoids

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15
Q

what is the management for a myxoedema coma?

A

Oxygen

Rewarming

Rehydration

IV T4/T3

IV hydrocortisone

Treat underlying cause (e.g. infection)

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16
Q

what are the complications of hypothyroidism?

A

Myxoedema coma

Myxoedema madness(psychosis with delusions and hallucinations or dementia)

Complication of treatment: if give XS amount of thyroxine-> suppresses TSH causing osteopenia and AF

17
Q

summarise the prognosis of patients with hypothyroidism?

A

Lifelong levothyroxine is required

Myxoedema coma mortality = 80%