define
overactive thyroid gland due to excess production of T3 and T4
causes
most= Grave's hyperfunctioning nodules tumours TSH secreting adenomas thyroiditis ectopic production (struma ovarii) factitious (exogenous intake)
define thyrotoxicosis
physiological state where tissues are exposed to excess thyroid hormone caused by anything
hyperthyroidism is caused by only the thyroid gland
thyrotoxicosis causes associated with hyperthyroidism
excessive thyroid stimulation e.g. Grave’s, Hashitoxicosis, thyrotropinoma (TSHoma), thyroid cancer and choriocarcinoma
thyroid nodules with autonomous function e.g. multinodular goitre or toxic solitary nodule
thyrotoxicosis causes not associated with hyperthyroidism
- thyroiditis e.g. subacute, post-partum and drug-induced
- exogenous thyroid hormones e.g. over treatment with levothyroxine and thyrotoxicosis factitia
- ectopic thyroid tissue e.g. metastatic thyroid carcinoma and struma ovarii (teratoma containing thyroid tissue)
presentation of thyrotoxicosis
- cardiac= palpitations, AF, HF
- sympathetic= tremour, sweating
- CNS= anxiety, nervous, irritable, insomnia
- GI= frequent, loose stools
- vision= lid retraction, double vision (diplopia) and proptosis (Grave’s)
- brittle, thin hair
- rapid finger nail growth
- light bleeding and less frequent periods
- proximal muscle weakness
- increased BMR, weight loss despite increased appetite
- thermogenesis: intolerance to heat and excess sweating
define Grave’s disease
this is an AI with antibodies to the TSH receptor, thyroid peroxisomes and thyroglobulin
who is Grave’s disease more common in>?
women 20-40/50
presentation of Grave’s
- hyperthyroidism with diffuse enlargement of the thyroid
- bruit over large goitre (hypervascularity)
- eye disease (smoking) e.g. exophthalmos (fibroblasts expressing TSH receptor). TRAb driven pathology
- pretibial myxoedema- orange peel
- clubbing (thyroid acropachy)
BUZZWORDS= eye change, gritty eyes and smooth velvety skin
eye disease management in graves
mild= topical lubricants severe= steroids, radiotherapy and surgery
diagnosis of Grave’s
- low TSH and high T3/4
- autoantibodies e.g. thyroid stimulating immunoglobulin, thyroid growth stimulating immunoglobulin
- TSH binding inhibitor immunoglobulins (episodes of hypofunction)
- TSH receptor antibody (TRAb)
- other antibodies e.g. anti-TPO and anti-Tg
- hypercalcaemia and high ALK (increased bone turnover and associated osteoporosis)
- leukopenia, often related to treatment (ATD-induced agranulocytosis)
mechanism of management for Grave’s disease
block TPO thyroid hormone synthesis
management of Grave’s
- carbimazole
- propylthiouracil (PTU) only 1st line in first trimester (10x less potent than carbimazole
- beta blockers for symptomatic management (first line propranolol)
mechanism of action of PTU
inhibits DIO1 which lowers T4 to T3 conversion
adverse of carbimazole
aplasia cutis in early pregnancy
adverse of PTU
liver failure
risks in ATDs?
generally well-tolerated but some have allergic reaction, liver problems and risk of agranulocytosis (if this happens ATDs cannot be used again- risk highest in first 6 weeks, no evidence for monitoring FBC)
when to stop ATDs
stop if fever, oral ulcer or oropharyngeal infection
management for relapsed Grave’s and nodular thyroid disease
radioiodine
if managing with radioiodine with eye disease what must be used?
steroid cover
risks in RAI
hypothyroidism
when is thyroidectomy used?
when RAI is contraindicated
surgical risks of thyroidectomy
recurrent laryngeal nerve palsy
hypothyroidism
hypoparathyroidism
define thyroid storm (crisis)
this is a medical emergency due to hyperthyroidism
