What is secondary thyroid disease?
Hypothalmic or pituitary disease
(this will indirectly impact the thyroid)
What is a goitre?
A swelling in the neck from an enlarged thyroid
By what other name is thyrotropin known?
Thyroid stimulating hormone
Which cells secrete TSH?
How are T3/T4 produced?
- Postive stimulus on hypothalamus
- Thyroid releasing hormone secreted
- TRH acts on anterior pituitary
- Thyroid stimulating hormone secreted
- TSH acts on thyroid
- T3/T4 produced
At which pointsin the hypothalmic-pituitary-thyroid axis can T3/T4 self regulate their release?
- Act on hypothalamus to reduce TRH release
- Act on pituitary to reduce TSH release
What are the thyroid hormone levels like in primary hypothyroidism?
Free T3/4 low
What are the thyroid hormone levels like in primary hyperthyroidism?
Free T3/4 high
What are the thyroid hormone levels like in secondary hypothyroidism?
Free T3/4 low
TSH low (or "normal" within the context)
What are the thyroid hormone levels like in secondary hyperthyroidism?
Free T3/4 high
TSH high (or "normal" in the context)
Hypothyroidism is the product of any disorder that results in what?
Insufficient thyroid hormone secretion
What is myxoedema?
Pretibial myxoedema is a rare clinical sign of which condition?
Hypothyroidism is most common in which ethnic background?
Chronic thyroiditis is known by which other term?
What can cause chronic goitrous thyroiditis (Hashimoto's)?
- Iodine deficiency
- Drugs (amiodarone, lithium)
- Maternal transmission (antithyroid drugs)
- Hereditary biosynthetic defects
Non-goitrous primary hypothyroidism is known by which other term?
What may induce non-goitrous primary hypothyroidism?
- Post-ablative therapy (radioiodine, surgery)
- Post-radiotherapy (e.g. lymphoma treatment)
- Congenital developmental defect
Self-limiting primary hypothyroidism may be the result of which 3 main things?
- Withdrawal of antithyroid drugs
- Subacute thyroiditis with transient hypothyroidism
- Post-partum thyroiditis (immediately following birth)
What are some causes of secondary hypothyroidism?
- Cranial radiopathy
What is the most common cause of autoimmune hypothyroidism in the western world?
How is autoimmune (Hashimoto's) thyroiditis characterised?
- Antibodies against thyroid peroxidase (TPO)
- T cell infiltrate and inflammation
Which parts of the body are affected in hypothyroidism?
- Hair and skin
How are the hair and skin affected in hypothyroidism?
- Coarse, sparse hair
- Dull expressionless face
- Periorbital puffiness
- Pale cool skin that feels doughy
- Pitting oedema
How is the cardiovascular system impacted by hypothyroidism?
- Reduced heart rate
- Cardiac dilatation
- Pericardial effusion
- Worsening heart failure
How are metabolic processes affected in hypothyroidism?
- Slowed, decreased appetite, weight gain
How is the GI system affected in hypothyroidism?
- Megacolon and intestinal obstruction
How is the respiratory system affected in hypothyroidism?
- Deep hoarse voice
- Obstructive sleep apnoea
What is macroglossia?
Abnormally enlarged tongue
How is the CNS affected in hypothyroidism?