Hyperthyroidism Flashcards
What are examples of primary causes of hyperthyroidism?
Grave’s disease= AI Ab which mimic TSH and increase stimulation of TSH receptors
Thyroiditis= inflammation associated with viral infection
Toxic multinodular goitre= nodules form on surface of thyroid gland which work independently to the normal negative feedback mechanisms
What are secondary causes of hyperthyroidism?
Drug induced= iodine/amiodarone/Lithium
Pituitary adenoma
Exogenous thyroid hormone release= ovarian germ cell tumour
What is thyrotoxicosis?
What are the possible causes of thyrotoxicosis?
Abnormally excessive concentration of thyroid hormone in body
Grave’s disease
Toxic multinodular goitre
Solitary toxic thyroid nodule
Thyroiditis (De Quervain’s/Hashimotos/drug-induced/postpartum)
Thyroid storm
What signs and symptoms are universal in hyperthyroidism?
(Things speeding up) Anxiety + irritability Sweating Heat intolerance Tachycardia Weight loss Fatigue Frequent loose stools Amenorrhea/oligomenorrhea Sexual dysfunction
What causes Grave’s disease?
How might someone with Grave’s disease present?
TSH receptor antibodies= mimic TSH and increase stimulation of thyroid
(SPECIFIC FEATURES OF GRAVE’S)
Diffuse goitre w/o nodules
Exophthalmos= due to inflammation, swelling and hypertrophy of tissue behind the eye in response to TSH receptor antibodies
Pretibial myxoedema= mucin deposits (appear waxy) on anterior part of leg due to reaction to TSH receptor antibodies
Grave’s eye disease= itching/watery/gritty
What are toxic multinodular goitres and why do they form?
What group of patients is toxic multinodular goitre almost always associated with?
Nodules producing excessive TH independent of negative feedback mechanism
Form due to relative iodine deficiency causing increased TSH drive causing increased thyroid growth-> leads to nodule formation
Nodules develop autonomous tissue which becomes the DOMINANT nodule due to the surround thyroid tissue not receiving as much TSH due to negative feedback processes stimulated by autologous TH production
Patients over 50-> tends to be gradual onset of thyrotoxicosis
What is De Quervain’s thyroiditis?
How does it differ from other causes of hyperthyroidism?
Viral infection presenting with neck pain, fever, tenderness, dysphagia and hyperthyroidism features
It is SELF-LIMITING
-has hyperthyroid phase followed by hypothyroid phase due to negative feedback and only requires supportive treatment for symptomatic relief
What is a thyroid storm?
How might someone experiencing a thyroid storm present?
Rare severe presentation of hyperthyroidism which requires monitoring and more intensive supportive treatment
Pyrexia
Tachycardia
Delirium
What investigations would you do in someone suspected of thyrotoxicosis?
TFT
-looking for high T4 and low TSH
Antithyroid peroxidase antibodies (anti-TPO)
-will be present in Graves
Antithyroglobulin antibodies
-will be raised in Graves
TSH receptor antibodies
-present in Graves disease
US
-looking for nodules
Radiosotope scan
- increase uptake in areas which have increased production of thyroid hormone
- diffuse high uptake= Grave’s
- focal high uptake= toxic multi nodular or adenomas
- cold areas= thyroid cancer
What would you expect the TFTs to be in thyrotoxicosis and why?
What is the exception to this presentation and why?
Raised free T4= measure of raised thyroid hormone
Low TSH due to negative feedback processes due to pituitary detecting high serum concentration of T3/T4
Exception= pituitary adenoma where producing own TSH so will be high
What imaging can be done to investigate possible hyperthyroidism?
US
- useful for thyroid nodules i.e. uninodular or multinodular
- distinguishing between cyst and solid nodule
Radioisotope scan
- radioactive iodine given IV or orally
- iodine uptake increases when thyroid cells are more active (hyperthyroidism)
- radioactive iodine gives of gamma rays which can be detected i.e. increased activity = increased gamma rays
How can hyperthyroidism by managed medically?
Carbimazole= 1st line
-anti-thyroid drug to try and return thyroid function and hormone levels back to normal
Propylthiouracil (PTU)= 2nd line
- anti-thyroid drug
- used in pregnancy or thyroid storm
- 2nd due to small risk of severe hepatic reaction
Beta-blockers= propranolol (non-selective)
-symptomatic control by managing the adrenaline-related symptoms associated with hyperthyroidism
Radioactive iodine
- emits radiation into thyroid gland to destroy portion of thyroid cells= decreases thyroid hormone production
- can cause hypothyroidism-> require levothyroxine after
What are the different options after patient has reached normal thyroid function (u-thyroid) on carbimazole?
Dose can be titrated so normal level maintained
-want to try and get patient on lowest dose possible
Block all production and patient given levothyroxine instead
How can hyperthyroidism be managed surgically? What needs to be done before surgery can be carried out?
Remove the entire thyroid or remove nodules
Need to be u-thyroid before surgery to prevent thyroid storm
