L14 - Thyroid Flashcards
(40 cards)
What is the function of thyroid hormones?
- Control of metabolism: energy generations and use
- Regulation of growth
- Multiple roles in development
Which thyroid hormone is the most biologically active one?
T3 is the biologically active hormone
What are the different thyroid hormone binding proteins?
- Serum albumin
- TBG (thyroxine binding globulin)
- Transthyretin
Which thyroid hormone has a greater percentage of being free?
T4 = 0.03% T3 = 0.3%
What would thyroid function tests show for hyperthyroidism?
- LOW serum TSH (thyroid stimulatinf hormone)
- HIGH serum free T4
- HIGH serum free T3
What would thyroid function tests show for hypothyroidism?
- HIGH serum TSH (thyroid stimulating hormone)
- LOW serum free T4
- LOW serum free T3
Which gender is thyroid disease more prevalent in?
- Hyperthyroidism
- Hypothyroidism
- Goitre
Female more common than men
What are the different possible aetiologies of hyperthyroidism?
- Graves’ hyperthyroidism (AI disorder)
- Toxic nodular goitre (single or multinodular)
- Thyroiditis (silent, subacute): inflammation
- Exogenous iodine (external origin)
- Factitious (taking excess TH)
- TSH secreting pituitary adenoma
- Neonatal hyperthyroidism
What are some symptoms of HYPERthyroidism?
- Tachycardia
- Heat sensitivity
- AF
- Shortness of breath
- Tremor
- Myopathy (muscle weakness)
- Weight LOSS
- INC appetite
What is Graves’ disease?
- AI disorder
- Most prevalent AID in UK and US
- Pathogenetic antibodies to TSH receptor on thyroid follicular cells (long acting thyroid stimulators)
- Interplay between genetic and environmental factors
- Environmental factors include: gender, stress, infection, pregnancy or drugs
What are some symptoms of graves disease?
- Anxiety and irritability
- Heat sensitivity
- Weight loss despite normal eating habits
- Goitre (enlargement of thyroid gland)
What are the different possible extra-thyroidal manifestations of the eye from Graves’ disease?
- Lid lag/ retraction
- Conjunctival oedema
- Periorbital puffinesss around the eye
- Proptosis (bulging)
- Ophthalmoplegia (weakness of eye muscles)
What are the different possible extra-thyroidal manifestations of the skin from Graves’ disease? (Dermopathy)
- Pretibial myxoedema
- Acropachy
What is pretibial myxoedema?
- Localised lesions of the skin
- Pretibial meaning myxoedema on the shins (result in swelling and lumpiness)
- Myxoedema is the deposition of hyaluronic acid
What is acropachy?
- Thickening of extremities
- Swelling and clubbing of fingers and toes
- Periostitis (inflammation of periosteum; the CT surrounding bone); most commonly the metacarpal bones
What causes neonatal hyperthyroidism?
- TSH-R antibodies cross the placenta
- Need to control hyperthyroidism in mother during pregnancy
- Mother has or had Graves’ disease
What are the different treatment options for HYPERthyroidism?
- Antithyroid drugs to block hormone synthesis
- Surgical removal of thyroid
- Radioiodine (131I) therapy
What are some of the different anti-thyroid drugs (thionamides)
- CARBIMAZOLE (methimazole)
2. PROPYLTHIOURACIL
How does propylthiouracil work?
Block iodine incorporation and organification through inhibition of thyroperoxidase
What would you need to consider before giving thionamide therapy?
- Rapid control, well tolerated
- Side effects
- Rash, joint pains, sickness
- Agranulocytosis: no WBC, infection risk
- Liver disease - Low cure rate
- (30-40% lower in men)
What would surgery involve when treating hyperthyroidism?
Total thyroidectomy: removal of whole thyroid gland
What are the complications of total thyroidectomy?
- Hypothyroidism
- Hypoparathyroidism: problems with calcium
- Recurrent laryngeal nerve damage
- Bleeding
- Thyroid storm: release of high concentrations of TH in circulation
What would radioactive iodine treatment for hyperthyroidism involve?
- Capsule (fixed dose)
- Highly effective (85% cure)
- Usually pre-treatment with drugs
- May worsen eye disease (treat with steroids)
What are the possible risks of giving iodine-131?
- Hypothyroidism (~60%)
- Cancer
- Infertility
- Teratogenesis (contra-indicated in pregnancy and breastfeeding - congenital malformations are produced in the embryo or foetus)