Hyperthyroidism Flashcards
What is primary thyroid disease?
Disease affecting the thyroid gland itself
Is primary thyroid disease always associated with a goitre?
No
Primary thyroid disease is most likely due to what type of disease?
Autoimmune
What will the TSH and free T3/4 levels be in primary hyperthyroidism?
TSH- low
Free T3/4- high
What causes secondary thyroid disease?
Hypothalamic or pituitary disease
What will the TSH and free T3/4 levels be in secondary hyperthyroidism?
TSH- high or ‘normal’
Free T3/4- high
Define thyrotoxicosis?
The clinical, physiological and biochemical state which arises when the tissues are exposed to too much thyroid hormone
Define hyperthyroidism?
Refers to the conditions in which overactivity of the thyroid gland leads to thyrotoxicosis
What are examples of thyrotoxicosis which ARE associated with hyperthyroidism?
Grave’s disease, toxic multi nodular goitre
What are examples of thyrotoxicosis which ARE NOT associated with hyperthyroidism?
Inflammation, thyroid treatment, ectopic production
What effect does hyperthyroidism have on thermogenesis?
Heat intolerance
What cardiac features can hyperthyroidism have?
Palpitations (AF), cardiac failure
Hyperthyroidism increases the activity of the sympathetic nervous system, what 2 clinical symptoms does this cause?
Increased sweating and tremor
What CNS effects does hyperthyroidism cause?
Anxiety, irritability, sleep disturbance
What GI effect does hyperthyroidism cause?
Diarrhoea
What are some vision problems that hyperthyroidism causes?
Lid retraction, double vision
What visual problem is specific to Grave’s disease?
Proptosis
What hair and nail changes does hyperthyroidism cause?
- Thin, brittle hair
- Fast growing nails
What effect does hyperthyroidism have on the menstrual cycle and periods?
Change in pattern of menstrual cycle
Lighter and less frequent periods
What effect does hyperthyroidism have on the muscles? Where specifically?
Weakness- specifically in the thighs and upper arms
What effect does hyperthyroidism have on appetite and weight?
Increased appetite and weight loss
What type of disease is Grave’s?
Autoimmune
In Grave’s, there are polymorphisms in genes associated with what? What are some examples of these genes?
T cell function- CTLA-4 and PTPN- 22
85% of hyperthyroidism is due to what?
Grave’s disease
Which sex is affected more by Grave’s disease? How much more likely is this sex to suffer from the disease?
Women- 10 times more likely
What age group does Grave’s disease affect?
20-50
Sisters and children of women with Grave’s disease have what chance of getting a thyroid autoimmune condition?
5-8%
What social factor can make Grave’s disease more severe and harder to treat?
Smoking
What will thyroid function tests for Grave’s disease show?
Increased T3/4, decreased TSH
Grave’s disease is associated with what MSK condition?
Osteoporosis
Increased bone turnover in osteoporosis does what to calcium and ALP levels
Raises them
What is the major auto-antibody associated with Grave’s disease?
TRAb (TSH receptor antibody)
What is diagnostic of Grave’s disease, without imaging?
Clinical signs and positive TRAb test
What antibodies may be present in Grave’s disease besides TRAb?
Anti-TPO
Anti-thyroglobulin
What are 4 clinical signs, specific to Grave’s disease?
- Pretibial myxoedema
- Finger clubbing
- Thyroid bruit
- Grave’s eye disease
Grave’s eye disease affects around 20% of sufferers and has a strong association with what?
Smoking
What is responsible for driving the pathology of Grave’s eye disease?
TRAb
How is thyroid eye disease treated?
If mild- topically
If severe- steroids, radiotherapy, surgery
What is the classic triad of Grave’s disease?
Hyperthyroidism with a goitre, eye changes and pretibial myxoedema
In what two groups of people is toxic multi nodular goitre more common?
Elderly and iodine deficient
What will thyroid function tests for toxic multi nodular goitre show?
- TSH low
- Free T3/4 high
Will there be autoantibodies in toxic multi nodular goitre?
No
What investigations can be performed for toxic multi nodular goitre?
- Iodine uptake scan
- US (+/- FNA)
When does surgery become the first line treatment for a patient with toxic multi nodular goitre?
If the patient is showing compression symptoms e.g. dyspnoea or dysphagia
What is the first line treatment for toxic multi nodular goitre?
Radioiodine
What are examples of inflammatory causes of thyrotoxicosis?
- Subacute DeQuervain’s
- Post-partum
- Drug induced (e.g. amiodarone)
What are two examples of exogenous thyroid hormones causing thyrotoxicosis?
- Overtreatment with thyroxine
- Thyrotoxicosis factitia
What are two examples of ectopic thyroid production?
Metastatic thyroid carcinoma
Other carcinoid tumours
What problem in the brain can cause thyrotoxicosis?
TSH secreting pituitary adenoma
What is a thyroid storm?
Emergency severe hyperthyroidism
What symptoms are present in a thyroid storm?
Respiratory and cardiac failure, hyperthermia and exaggerated reflexes
Who is a thyroid storm typically seen in?
Hyperthyroid patients with an acute illness or following thyroid surgery
How should you treat a thyroid storm?
Iodine, glucocorticoids, PTU, beta blockers, fluids and monitoring
What is the mechanism of anti-thyroid drugs?
Inhibit TPO
What is the first line drug for thyrotoxicosis? How often is it given?
Carbimazole once a day
What is the risk of carbimazole during pregnancy?
Risk of aplasia cutis in early pregnancy
What is the second line drug for thyrotoxicosis?
Propylthiouracil (PTU)
When does PTU become the first line drug for thyrotoxicosis?
During the first trimester of pregnancy
How often is PTU taken?
Twice daily
How does PTU work?
Inhibits DI01 which decreased T4-T3 conversion
There is a very low risk of what organ failure with PTU?
Liver
What is the first line treatment for Grave’s Disease?
Drugs
What are the two methods of giving drugs in Grave’s Disease?
Dose titration (12-18 months) Block and replace (6 months but higher recurrence)
What is the treatment for recurrent Grave’s disease?
Radioiodine or surgery
What are some generic complications of anti-thyroid drugs?
- Allergic reactions
- Cholestatic jaundice
- Increased liver enzymes
- Fulminant hepatic failure
What is the major side effect of anti-thyroid drugs? What should patients be warned to look out for?
Agranulocytosis- stop the drug and get FBCs if there is fever, oral ulcers or oropharyngeal infections
What specific drug is used for symptomatic relief during the first few weeks of treatment?
Propranolol
Is there a risk of cancer with radio iodine?
No
Is radio iodine safe in pregnancy?
No
Aside from pregnancy, when else should radio iodine not really be used?
- Thyroid eye disease (except with steroid cover)
- Those with young children (contact precautions)
What downside can happen to patients following radio iodine treatment?
They become hypothyroid and have to take thyroxine
When is a thyroidectomy used?
When radioiodine is contraindicated
What are the risks of a thyroidectomy?
Recurrent laryngeal nerve palsy, hypothyroidism, hypoparathyroidism