Hyperthyroidism Flashcards
What is hyperthyroidism?
Clinical effects from overactive thyroid => releasing excess thyroid hormone due to gland hyper function
Who does it affect?
Females > males 5:1
Between 20-40 years of age
What are the symptoms of hyperthyroidism?
Weight loss
Increased appetite, thirst
Diarrhoea
Over-active, sweating, heat intolerance
Palpitations, tremor
Irritability, labile mood, restlessness
Oligomenorrhoea ± infertility ; loss of libido
Goitre
Rarely: itching, urticaria, chorea, panic, alopecia
What are the signs of hyperthyroidism?
Fine tremor* ; hyperkinesis*
Tachycardia* or AF*
Warm, sweaty peripheries*
Systolic hypertension
Cardiac failure
Exophthalmos** ; lid lag and stare* ; lid retraction
Conjunctival oedema ; periorbital oedema
Goitre*
Weight loss
Proximal myopathy ; proximal muscle wasting ; palmar erythema
Graves dermopathy**
- = signs of greater discriminative value
- = signs specific to graves’ disease
What are the causes of hyperthyroidism?
- Graves’ disease
- Toxic multi nodular goitre
- Toxic adenoma
- Ectopic thyroid tissue
- Exogenous i.e. iodine excess
- Others:
=> Subacute de Quervain’s thyroiditis - self limiting post viral with painful goitre + high temp ± raised ESR. Treat with NSAIDs.
=> Drugs i.e. amiodarone, lithium (hypo more common)
=> Postpartum
What is the most common cause of hyperthyroidism?
Describe how it causes hyperthyroidism?
Who does it affect?
Grave’s disease = most common cause of hyperthyroidism
Graves’ disease is an autoimmune condition.
=> IgG antibodies bind to g-protein coupled thyrotropin receptors in the thyroid gland leading to excess thyroid hormone production and smooth thyroid enlargement
=> IgG antibodies mimic TSH - these TSH receptor antibodies are specific for Grave’s
=> Assoc. with HLA-B8, DR3, DR2
=> Assoc. with other autoimmune conditions i.e. pernicious anaemia, vitiligo, myasthenia gravis, addison’s
=> Triggers: stress, infection, childbirth
=> commonly affects women > men 9:1 ; between 40-60yrs
How does solitary toxic adenoma/nodule cause hyperthyroidism?
Solitary toxic adenoma/nodule = 5% of total hyperthyroidism cases
=> solitary nodules producing T3/T4
=> isotope scan: nodule is ‘hot’ ; rest of the gland suppressed
How does toxic multi-nodular goitre cause hyperthyroidism?
=> Seen commonly in elderly women & iodine deficient areas
=> Nodules that secret thyroid hormone
=> Surgery indicated if compression from enlarged thyroid resulting in
How does ectopic thyroid tissue cause hyperthyroidism?
Metastatic follicular thyroid cancer
or
Ovarian teratoma with thyroid tissue
Hyperthyroidism:
Elderly: common presentation with AF, other tachycardias or heart failure => thyroid function test mandatory in anyone with AF
Children: excessive height or growth rate or behavioural problem i.e. hyperactivity
INFO CARD
What investigations are needed to diagnose hyperthyroidism?
- Serum TSH is suppressed
- Raised free T3 or T4
- TSH receptor stimulating antibodies (TSHR-Ab) - specific for Graves’
- Isotope scan if cause is unclear - detects nodular disease
- If ophthalmopathy: test visual fields, acuity, eye movements
- Mild normocytic anaemia, mild neutropenia in Graves ; raised ESR, calcium, LFT
How do you manage hyperthyroidism with medication?
Beta blocker i.e. propranolol for symptom control
=> many hyperthyroid manifestation mediated via sympathetic system
Anti-thyroid drugs:
2 strategies both equally effective
I. Titration e.g. Carbimazole 20-40mg daily for 4wks then reduce according to thyroid function test every 1-2months
II. Block & replace: Carbimazole 40mg daily to completely suppress thyroid gland + levothyroxine 100ug to replace thyroid hormone
=> maintain course for 12-18mths in Graves’
=> 50% relapse & may require iodine therapy or surgery
How and when do you manage hyperthyroidism with radioactive iodine and surgery?
Consider surgery or radioiodine if: Recurrent hyperthyroidism after drugs, Persistent drug side-effects, Poor compliance or Patient choice
Consider surgery if:
Large goitre which is unlikely to remit after anti-thyroid medication
=> Iodine accumulates in the thyroid and destroys the gland by local radiation - may take several months to be effective
=> Iodine contraindicated in pregnancy and lactation
=> Total thyroidectomy : risk of damage to recurrent laryngeal nerve (hoarse voice) and hypoparathyroidism
Patient will become hypothyroid after surgery and likely to after iodine therapy too => thyroid replacement therapy
What is the major side effect of drug therapy in hyperthyroidism?
Agranulocytosis
=> patients warned to seek immediate attention if:
unexplained fever or sore throat
What are the complications of hyperthyroidism?
Heart failure (thyrotoxic cardiomyopathy - risk high in elderly)
Angina
AF
Osteoporosis
Ophthalmopathy
Gynaecomastia
Thyroid storm
What is thyroid storm / crisis?
How do you treat it?
Rare complication => rapid deterioration of hyperthyroidism with hyperpyrexia, severe tachycardia, extreme restlessness, cardiac failure and liver dysfunction.
=> Mortality of 10%
=> Precipitated by stress, infection, surgery or radio-iodine therapy but careful management avoids this
Treatment is urgent => propranolol in full dose with potassium iodide, anti-thyroid drugs and corticosteroids
=> suppresses manifestation of hyperthyroidism + supportive therapy
What is ophthalmopathy aka Graves’ orbitopathy aka thyroid eye disease?
Retro-orbital inflammation and lymphocyte infiltration => swelling of the orbit
Seen in 25-50% of people with Graves’ disease
Main risk factor = smoking
Eye disease = may be first presenting sign in Graves + can be worsened by treatment i.e. radioactive iodine
What are the symptoms of thyroid eye disease?
Eye discomfort
Grittiness
Increased tear production
Photophobia
Diplopia
Reduced acuity
Afferent pupillary defect may mean optic nerve compression
What are the signs of thyroid eye disease?
Exophthalmos = protruding eyes
Proptosis = eyes protruding beyond the orbit
Conjunctival oedema
Corneal ulceration
Papilloedema
Loss of colour vision
Ophthalmoplegia due to muscle swelling & fibrosis
How do you manage thyroid eye disease?
Stop smoking
Treat hyper/hypothyroidism
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