Hyperthyroidism, Hypothyroidism and Thyroiditis Flashcards
what causes secondary thyroid disease
hypothalamic or pituitary disease
what is thyrotropin
thyroid stimulating hormone
what makes up 80% of TSH
T4- biologically inactive
what plasma proteins does TSH bind to
TBG, albumin, pre albumin
what is TSH released in response to
TRH
what happens to TSH when you are hypothyroid
is increased in attempt to get euthyriod
what is diodination
removal of iodine - T4 into T3
what are hormone levels like in primary hypothyroidism
free T3/4 low
TSH high
what are hormone levels like in primary hyperthyroidism
free T3/4 high TSH low (often 0)
what are hormone levels like in secondary hypothyroidism
free T3/4 low
TSH low/ normal
what are hormone levels like in secondary hyperthyroidism
free T3/4 high
TSH high/ normal
what is myxoedema
either
coma-severe hypothyroidism, a medical emergency
or
swelling of the skin and underlying tissues giving a waxy consistency, typical of patients with underactive thyroid glands.
what is pretibial myxoedema
sign of graves disease (hyperthyroidism) - infiltrative dermopathy resulting in localised lesions of the skin
what ethnicity is hypothyroidism most common in
white populations
what are the causes of primary goitrous hypothyroidism
chronic thyroiditis (hashimotos), iodine deficiency, drug induced (amiodarone, lithium), maternally transmitted (antithyroid drugs e.g. for graves), hereditary biosynthetic defects
what are the causes of primary non- goitrous hypothyroidism
atrophic thyroiditis (untreated hashimotos), post ablative therapy (radioiodine, surgery), post-radiotherapy (lymphoma treatment), congenital developmental defect
what are the causes of primary self limiting hypothyroidism
withdrawal of antithyroid drugs, subacute thyroiditis with transient hypothyroidism, post partum thyroiditis
what is hashimotos disease
autoimmune hypothyroidism - autoimmune destruction of thyroid gland and reduced thyroid hormone production
what characterised hashimotos (antibodies and histologically)
antibodies against thyroid peroxidase (TPO)
T cell infiltrate and inflammation microscopically
what are the clinical features of hypothyroidism in the hair and skin
coarse sparse hair,
dull expressionless face,
periorbital puffiness,
pale cool skin that feels doughy to touch,
vitiligo may be present (another autoimmune disease),
hypercarotenaemia (yellowing of the skin)
what are the clinical features of hypothyroidism in thermogenesis
cold intolerance
what are the clinical features of hypothyroidism in fluid balance
fluid retention- pitting oedema
what are the cardiac clinical features of hypothyroidism
reduced heart rate, cardiac dilatation, pericardial effusion, worsening of heart failure
what are the metabolic clinical features of hypothyroidism
hyperlipidaemia, decreased appetite, weight gain