Hypothyroidism Flashcards
What are the 3 types of hypothyroidism?
Goitrous
Non-goitrous
Self-limiting
What are some causes of goitrous hypothyroidism?
- Hashimoto’s thyroiditis (Chronic thyroiditis)
- Iodine deficiency
- Drugs (e.g. amiodarone, lithium)
- Maternally transmitted (e.g. anti-thyroid drugs)
- Hereditary biosynthetic defects
What are some causes of non-goitrous hypothyroidism?
- Atrophic thyroiditis
- Ablative surgery (e.g. radioiodine, surgery)
- Radiotherapy
- Congenital developmental defect
What are some causes of self-limiting hypothyroidism?
- post-partum thyroiditis
- withdrawal of antithyroid drugs
- subacute thyroiditis
What is Hashimoto’s thyroiditis?
Hashimoto’s thyroiditis is an autoimmune condition causing chronic thyroiditis and therefore hypothyroidism
It results in autoimmune destruction of the thyroid gland, leading to reduced thyroid hormone production
What is the most common cause of hypothyroidism in the Western world?
Hashimoto’s thyroiditis
Who is most at risk of Hashimoto’s thyroiditis?
Younger patients
Females
Family history
What immune components are present in Hashimoto’s thyroiditis?
- CD8+ T cells
- Anti-thyroid antibodies
- Gamma-interferon + Macrophages
- Lymphocytes
What antibodies are found in Hashimoto’s thyroiditis?
- Anti-TPO (Thyroid PeriOxidase)
- Anti-thyroglobulin
What will histological testing show in Hashimoto’s thyroiditis?
Prominent lymphoid infiltrate, containing:
- Lymphocytes
- Plasma cells
- Reactive follicles with germinal centres
There will also be thyroid follicle atrophy, causing the formation of Hurthle cells (Follicular cells that incorrectly regenerate, leading to eosinophilic cytoplasm formation)
May see progressive fibrosis within the glan
What are Hurthle cells?
Follicular cells that incorrectly regenerate, leading to eosinophilic cytoplasm formation)
What are some causes of secondary hypothyroidism?
- Infection
- Malignancy
- Trauma
- Congenital
- Cranial radiotherapy
- Drugs
What are the main symptoms and signs of hypothyroidism?
- Reduced basal metabolic rate
- Slow pulse rate
- Fatigue, lethargy, slow response times and mental sluggishness
- Cold-intolerance
- Tendency to put on weight easily
What is caused by reduced BMR in hypothyroidism?
Reduced basal metabolic weight means there may be hyperlipidaemia and decreased appetite (But still weight gain)
What are some hair and skin symptoms of hypothyroidism?
- Coarse, sparse hair
- Dull, expressionless face
- Periorbital puffiness
- Pale cool skin that feels doughy
- Vitiligo
- Hypercarotenaemia (yellow skin-pigmentation)
What is vitiligo?
Vitiligo is a skin condition that forms as a result of a number of autoimmune conditions
What are some cardiac symptoms of hypothyroidism?
- Cardiac dilatation
- Pericardial effusion
- Worsening of heart failure
- Pitting oedema
What are some gastrointestinal symptoms of hypothyroidism?
- Constipation
- Megacolon
- Intestinal obstruction
- Ascites