hyperthyroidism Flashcards
what is hyperthyroidism?
over-production of the thyroid hormones by the thyroid gland
what are the thyroid hormones?
triiodothyronine (T3) and thyroxine (T4)
what is meant by thyrotoxicosis?
effects of an abnormal and excessive quantity of thyroid hormones in the body
what is meant by primary hyperthyroidism?
- due to thyroid pathology
- the thyroid is behaving abnormally and producing excessive thyroid hormones
what is meant by secondary hyperthyroidism?
- due to the pathology in the hypothalamus or pituitary
- pituitary produces too much thyroid stimulating hormone
- the hyperthalamus produces too much thyroid releasing hormone
what is meant by subclinical hyperthyroidism?
- where thyroid hormones T3 and T4 are normal and TSH is suppressed
- absent or mild symptoms
what is graves disease?
- autoimmune condition
- TSH receptor antibodies cause primary hyperthyroidism
- the antibodies are produced by the immune system
- they stimulate TSH receptors on the thyroid
- this is the most common cause of hyperthyroidism
what is plummers disease and whats it also known as?
- toxic multinodular goitre
- where nodules develop on the thyroid gland
- these are unregulated in the thyroid axis so produce excessive thyroid hormones
- most common in patients over 50 years
what is exophthalmos, what’s another name for it and what causes it?
- proptosis
- bulging of the eyes
- caused by graves disease
- inflammation, swelling and hypertrophy of the tissue behind the eyeballs force them forward, causing them to bulge out their sockets
what is pretibial myxoedema and what causes it?
- skin condition caused by deposits of glycosaminoglycans under the skin on the anterior aspect of the leg
- gives skin a discoloured, waxy, oedematous apearence over this area
- specific to graves
is a reaction to the TSH antibodies
what are the 3 symptoms specific to graves disease?
exophthalmos / proptosis
pretibial myxoedema
goitre
what is goitre?
- neck lump caused by the swelling of the thyroid gland
what are the causes of hyperthyroidism and what is the nemonic to remember this?
GIST
Graves disease
Inflammation (thyroiditis)
Solitary toxic thyroid nodule
Toxic multinodular goitre
What is thyroiditis and its initial and delayed effects?
- inflammed thyroid gland
- initial hyperthyroidism
- followed by hypothyroidism
what are the causes of thyroiditis?
- de quervains thyroiditis
- hashimotos thyroiditis
- postpartum thyroiditid
- drug-induced thyroiditis
what is the universal presentation of hyperthyroidism?
- anxiety and irritability
- sweating and heat intolerance
- tachycardia
- weight loss
- fatigue
- insomnia
- frequent loose stools
- sexual dysfunction
- brisk reflexes on examination
what are the specific features of graves, relating to the presence of TSH receptor antibodies?
- diffuse goitre (without nodules)
- graves eye disease, including exophthalmos
- pretibial myxoedema
- thyroid acropachy (hand swelling and finger clubbing)
in what situation may nodules be palpable?
in patients with toxic multinodular goitre
what is solitary toxic thyroid nodule and treatment?
- a single abnormal thyroid nodule acts alone, releasing excessive thyroid hormone
- usually benign adenomas
- treatment involves surgical removal
what is de quervains thyroiditis and whats another name for it?
- subacute thyroiditis
- condition causing temporary inflammation of thyroid gland
what are the 3 phases of de quervains thyroiditis?
- thyrotoxicosis
- hypothyroidism
- return to normal
what does the initial thyrotoxic phase of de quervains thyroiditis involve? (4)
- excessive thyroid hormones
- thyroid swelling and tenderness
- flu-like illness (fever, aches and fatigue)
- raised inflammatory markers (CRP and ESR)
what is the treatment for de quervains thyroiditis?
- its a self-limiting condition so supportive treatment is usually all that is necessary
-NSAIDs - for pain and inflammation
- beta blockers - for hyperthyroidism
- levothyroxine - for hypothyroidism
what is thyroid storm and what does it present with?
- more severe and rare presentation of hyperthyroidism
- also known as thyrotoxic crisis
presentation:
- fever
- tachycardia
- delirium
what are some treatment options for those with hyperthyroidism?
- first-line - carbimazole
- second-line - propylthiouracil
- radioactive iodine
- beta blockers
- surgery
what is the first-line drug for hyperthyroidism and describe how it works?
- Carbimazole
- Blocks synthesis of T4
- Normal thyroid function after 4-8 weeks (euthyroidism)
- Side Effects: agranulocytosis, liver function
- beta blocker (eg: propanolol) alongside for rapid symptom relief
whats the second-line method of treatment for hyperthyroidism, how is it used and why is it not preferred?
- Propylthiouracil
- Prevents T4->T3 conversion
- Small risk of severe hepatic reaction, including death
what does radioactive iodine treatment involve?
- drinking a single dose of radioactive iodine
- the thyroid gland takes this up
- the emitted radiation destroys a proportion of the thyroid cells
- the reduction in cells leads to a decrease in thyroid hormone production
- remissio can take 6 months after which the thyroid is underactive
- means long term levothyroxine is required
what are the strict rules of levothyroxine?
- women must not be pregnant or breastfeeding and must not get pregnant within 6 months of treatment
- men must not father children within 4 months of treatment
- limit contact with people after the dose, especially children and pregnant women
describe how beta-blockers are used in hyperthyroidism treatment?
- they block the adrenalin-related symptoms of hyperthyroidism
- propanolol is the usual drug as it non-selectively blocks adrenergic activity
- useful in patients with thyroid storm - doesnt treat the underlying problem
explain what surgeries are available and what is the concequence of them?
- removing whole thyroid gland
- removing only the toxic nodules
- patients will be hypothyroid after so will require life-long levothyroxine
Diagnosis of hyperthyroidism (4)
First line: TFT (thyroid function test)
- Anti-TSH receptor antibodies positive in Graves’
- Anti TPO antibodies in 80% of cases (but much more in hypo)
- Thyroid ultrasound
- technicium scan
Epidemiology and risk factors of hyperthyroidism (3)
- Middle aged women
- Family history
- Autoimmune diseases
General signs of hyperthyroidism (5)
- Postural tremor
- Palmar erythema
- Hyperreflexia
- Goitre
- Lid lag and retraction
Graves’ specific hyperthyroid signs (3)
- Exophithalmos or ophthalmoplegia (bulging eyes, eye paralysis)
- Pretibial myxedema (purple/redness) due to deposits of mucin under the skin (may also be seen in Hashimoto’s)
- Thyroid acropachy (clubbed fingers)
How to stop patients from becoming hypothyroid after hyperthyroidism treatment
Give them levothyroxine
Pathophysiology of Graves’ disease (2)
- Immune system produces TSH receptor antibodies that mimic TSH and stimulate the TSH receptors on the thyroid
- Increased T3 increases metabolic rate, CO, bone resorption and activates the sympathetic nervous system
Risk factors of hyperthyroidism (5)
- Smoking
- Stress
- HLA-DR3
- Female 20-40 years
- Other autoimmune diseases
Symptoms of hyperthyroidism (4)
- Heat intolerance and sweating
- Weight loss
- Palpitations
- Oligomenorrhoea
Symptoms of thyroid storm (4)
- NDV (Newcastle Disease Virus)
- Abdo pain
- Jaundice
- Confusion, delirium or coma
Tell me about De Quervain’s thyroiditis (2)
- Follows a viral prodrome and can also present with a transient thyrotoxic state
- Painful goitre with raised inflammatory markers. Usually self limiting
Tell me about Radioactive iodine treatment for hyperthyroidism (3)
- First line definitive treatment for Grave’s disease and toxic multinodulae goitre
- Destroys excess thyroid tissue
- It is kind of dangerous so avoid people, especially pregnant women and kids for a period of time
TFTs for hyperthyroidism (2)
- Low TSH, high T4 = primary hyperthyroidism (Graves’)
- High TSH, high T4 = secondary hyperthyroidism OR thyroid hormone resistance
What is toxic multinodular goitre? (also known as Plummer’s disease)
Nodules develop on the thyroid gland and produce excessive thyroid hormone
What to do after euthyroidism is achieved in hyperthyroid treatment (4)
Maintenance carbimazole using either:
- Titration block regimen
- Block and replace regimen
Complete remission achieved after 18 months of treatment (remission rate 50%)
Who would you not want to give carbimazole to?
Women wanting to get pregnant as it’s teratogenic (causes fetal abnormalities)
solidatory toxic nodule treatment
Technician scan and radioactive iodine RAI
Surgery
what scans can be used to view the thyroid?
- ultra sound
- 99mTechnicium pertechnetate
- CT
how betablockers work
Peripheral effects
Reduce T4 to T3 conversion peripherally
thyroid storm treatment
prothiuuricil 200-300 mg 6 hourly via NGT
Potassium iodide
Propranolol
Steroids
name some drugs which can affect the thyroid
Amiodarone
Lithium
Immune Therapies
most important symptom to council patient on when taking carbamizole or prouricil
Agranulocytosis
anti-tsh receptor positive
graves
atrial fibrillation
well known complication
what drug for first trimester pregnancy
prothilthiourcil
propranolol
used for post partum hypertension
which drug can be used in pregnancy
prothiouricil
