hypo and hyper thyroid Flashcards
what is thyrotoxicosis?
the clinical, physiological and biochemical state arising when tissues are exposed to excess thyroid hormone
what is hyperthyroidism?
refers specifically to conditions in which overactivity of the thyroid gland result in thyrotoxicosis
30 y/o women presents with heat intolerance, itchy skin and weight loss despite a bigger appetite. She is found to be anti-TSH positive - diagnosis?
What would you expect her TFTs to look like?
Grave’s disease
anti-TSH antibody = thyroid stimulating immunoglobulin (acts in same way as TSH)
low TSH and high fT4/3
(T4 always raised, T3 may be raised or normal)
What are some Grave’s specific signs and at which point in the disease progression would they occur?
Exophthalmus (1-2yrs post-diagnosis; can also precede it)
Pre-tibial myxoedema (1-2yrs after diagnosis)
Diffuse swelling/enlargement of thyroid
Thyroid acropatchy (finger clubbing)
Why are the eyes affecting in Grave’s?
the tissue & muscles around the eyes have similar receptors to TSH receptors so are stimulated by TSI; this leads to water build-up + retro-orbital swelling; collagen fibres are deposited -> loss of function + lack of eyeball movement
What does a thyroid bruit reflect?
defective of a hyper vascular thyroid; auscultate in Grave’s - not heard in other goitrous conditions
List some other lab abnormalities seen in Grave’s disease.
hypercalcaemia & high ALP (high bone turnover; assoc. with osteoporosis)
leucopenia (low WCC) - mild
TSH receptor antibody (TRAb); if raised titre is found, no need to image the gland
what is the treatment for thyroid eye disease?
mild -> topical lubricants
severe -> steroids/surgery (poor evidence for radiotherapy)
Older lady presents with an asymmetrical nodular lump in her neck. She seems agitated and she says she lost weight recently as well as feeling like she is having chest palpitations. Differential & tests?
toxic multi nodular goitre TRAb negative high fT4/3 and low TSH scintigraphy -> high uptake thyroid USS
thyroid crisis is typical in which patients?
normal hyperthyroid patients with an acute illness/infection or recent thyroid surgery
A middle aged female presents with bilateral plaque formation on her anterior shins which are non-pitting and “orange peel” looking. Diagnosis?
grave’s disease
What is the 1st line anti-thyroid drug and how does it work?
Carbimazole - inhibits TPO (thyroid/iodine peroxidase) thereby blocking thyroid hormone synthesis
What is the 1st line anti-thyroid drug during 1st trimester of pregnancy?
Propylthiouracil (PTU) - 10x less potent than carbimazole inhibits DI01 (reduces T4->T3 conversion)
What is the treatment for Grave’s?
dose titration carbimazole for 12-18 months or block & replace (6 months)
what are the side effects of anti-thyroid drugs?
1-5% develop allergic type reactions (rash, urticaria, arthralgia)
PTU - cholestatic jaundice, raised liver enzymes, fulminant hepatic failure
0.1-0.5% of patients develop agranulocytosis (ATDs can’t be used again)
What is fulminant hepatic failure?
encephalopathy + jaundice <2weeks in previously normal liver
When is the risk highest for developing agranulocytosis after starting anti-thyroid drugs? What should you tell the patient about it?
first 6 weeks highest risk
warn patient verbally & in writing to stop drug & have urgent FBC in event of fever, oral ulcer or oropharyngeal infection
Why do beta blockers have a place in hyperthyroidism treatment?
b-adrenoceptor blockaded decreases activity of sympathetic nervous system (thyroid hormones increase no. of adrenaline & NA receptors)
useful for immediate relief of thyrotoxic symptoms
Which beta-blocker is 1st choice in hyperthyroid?
propranolol - has added benefit of inhibition of DIO1
When do you have to be cautious with use of beta-blockers?
in asthmatics since risk of provoking bronchospasm; CCBs can be used instead, e.g. diltiazem
