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
