HYPERTHYROIDISM Flashcards
What is the cause behind Graves’ Disease?
Autoimmune antibodies bind to and stimulate the TSH receptor in thyroid causing hyperthyroidism and smooth goitre
What are some additional symptoms which may be seen in Graves
Exophthalmos - antibodies binding to muscles behind eye
Pretibial myxoema (hypertrophy) - swelling that occurs on the shins of patients
What should you see on a radioiodine uptake scan of a thyroid of a patient with Graves?
Diffuse goitre of moderate size and uniform/symmetrical radioiodine uptake
Describe and explain what Plummer’s disease is
Toxic nodular goitre
Not autoimmune (no antibodies)
Benign adenoma which is overactive in making thyroxine
What does a patient with Plummer’s disease/ toxic nodular goitre thyroid look like?
Increased thyroxine causes less TSH and the non-nodular parts become smaller and smaller causing unsymmetrical thyroid goitre
What are the effects of thyroxine on the SNS?
Sensitises beta 3 adrenergic receptors to ambient levels of adrenaline and noradrenaline. Thus sympathetic activation
What are some symptoms of hyperthyroidism?
Weight loss (despite increased appetite) Breathlessness Palpitations Tachycardia Sweating Heating intolerance Diarrhoea Lid lag
What is a thyroid storm?
Hyperthyroidism when patients are extremely sick and don’t see doctor until later
50% mortality if left untreated
What are the symptoms of a thyroid storm?
2 or more of the following symptoms:
- hyperpyrexia > 41 Celsius
- accelerated tachycardia
- cardiac failure
- delirium/frank psychosis
- hepaticellular dysfunction; jaundice
What are the treatments for hyperthyroidism?
Thyroidectomy
Radioiodine
Drugs
What are the 4 classes of drugs used in treatment for hyperthyroidism?
Thionamides (anti-thyroid) e.g. propylthiouracil, carbimazole
Potassium Iodide
Radioiodine
Beta-blockers - helps with symptoms by blocking SNS
When is potassium iodide used and why?
Used before surgery because it decreases gland vascularity and thus risk of blood loss - only works for 10 days
Thyroid storm
How do thionamides work?
Reduce T3/T4 synthesis by inhibiting thyroid peroxidase thus preventing iodination
How long does it take for the effects of thionamides?
6 weeks since there is still stored thyroxine which is used. It just means new T3/T4 won’t be made. Give beta-blockers in meantime as effect is instant
What are 2 adverse effects of thionamides?
Agranulocytosis (reduction in granulocytes) rarely occurs on withdrawal of drug
Rashes - common
After how long should you aim to stop anti-thyroid drug treatment?
18 months
Why is KI given to hyperthyroid patients and what occurs when you give it?
Inhibits H2O2 generation and iodination of thyroglobulin
Hyperthyroid symptoms reduce in 1-2 days
Vascularity and gland size reduce in 10-14 days
What are the risks of a thyroidectomy?
Voice change
Loss of parathyroid glands
Who should not have radioiodine?
Pregnant women and children
What is 99-Tc-pertechnetate?
Cheap version of radioiodine
What is viral (de Quervain’s) thyroiditis and what does it cause?
Viral infection of thyroid, causes:
- painful dysphagia
- hyperthyroidism
- pyrexia (fever)
- thyroid inflammation
- tender to touch
What can you expect to see in radioiodine scan for a patient with viral thyroiditis?
Nothing because there is no iodine uptake since the thyroid cells have been hijacked and instead of making thyroxine they make viruses.
Describe the medical course a patient with viral thyroiditis can expect
Initial hyperthyroidism as stored thyroxine is released
4 weeks later hypothyroid as thyroxine stores exhausted
After further month resolution and patient becomes euthyroid again.
If a patient has viral thyroiditis should you give thyroid replacement treatment?
No as that will complicate it, best let it run its course
Difference between postpartum thyroiditis and viral thyroiditis?
Similar but in postpartum no pain/tenderness and only occurs after pregnancy
