Hyperthyroidism Flashcards
What are the signs + symptoms?
Brittle hair/hair loss
Reduced focus
Enlarged thyroid
Increased metabolism (weight loss)
Diarrhoea
Muscle weakness
Sweating
What can be a result of hyperthyroidism?
Graves’ disease
Nodular disease
Thyroiditis
What is Graves’ disease?
Eyelids retract
Bulging eyes
Redness
What is nodular disease?
Thyroid grows nodules
Single or multinodular goiter
Women over 60
What is thyroiditis?
Inflammation of thyroid follicles
What is thyroiditis caused by?
Infection, trauma, drug induced or autoimmune
= T3/T4 leak from inflamed cells
How do you diagnose?
Symptoms
TFTs
- TSH
- FT4
- FT3
TRABs
What does TFT show if hyperthyroidism of thyroidal origin?
TSH low
BUT FT4 + FT3 raised
What does a definitive diagnosis require?
2 sets of TFTs taken at least 6 weeks apart
What does TFT show if hyperthyroidism of extrathyroidal origin (pituitary/hypothalamic disease)?
TSH raised
FT3 + FT4 raised
What is thyroiditis confirmed with?
TRABs
What do you conduct if TRABs test comes back negative?
Radioactive iodine uptake scanning
What are the aims of treatment?
Acute = manage symptoms
Chronic = effectively supress thyroid hormone
What are the choices for treatment?
Antithyroid drugs
Radioactive iodine
Thyroidectomy
What is 1st line for Graves’ disease if likely to go into remission?
Thionamides
Carbimazole
What is 1st line for Graves’ disease if unlikely to go into remission?
Radioactive iodine
What is 1st line for Graves’ disease if concerns regarding compression/malignancy?
Thyroidectomy
What is 1st line for multinodular goitre?
Radioactive iodine
2nd line = thionamides/thyroidectomy
What is 1st line for single nodular?
Radioactive iodine/surgical intervention
2nd line = thionamides
What is 1st line in pregnancy?
Thionamides/propylthiouracil
2nd line = thyroidectomy
What is contraindicated in pregnancy + breastfeeding?
Radioactive iodine
= potentiate thyroid hormone release = precipitate thyroid crisis = teratogenic
What is 1st line for children with Grave’s disease?
Thionamides/carbimazole
What is 1st line for children with MNG/SN?
Thionamides
Long term = risk/benefits of radioactive iodine/thyroidectomy
What are the most common antithyroid (thionamides) drugs?
Thionamides
Carbimazole (1st line unless pregnant)
Propylthiouracil
How long does it take to see therapeutic effect with thionamides?
6-8 weeks
What are the choices for regime with thionamides?
Titration
OR
Block + replace = high dose = destroy + terminate thyroid hormone = given alongside with levothyroxine
What is carbimazole?
Pro-drug undergoes hepatic metabolism
= problem with liver?
How long does carbimazole take to show therapeutic effect?
4-8 weeks
What is the mechanism of action of carbimazole?
Inhibition of organification of iodine + thyroglobulin + coupling of iodothyronine residues
= supress synthesis of thyroid hormones
What is the initial dose of carbimazole?
20-60mg daily dose in divided doses
How often should TFTs be checked with carbimazole?
Every 6-8 weeks
What happens once thyroid levels are within reference range, carbimazole?
Choose either “titration” or “block + replace” + continue for 12-18 months
What is the titration for carbimazole?
5-15mg OD
Regular TFTs
What is block + replace for carbimazole?
High starting dose till production suppressed
Levothyroxine alongside
What are the side effects of carbimazole?
Macropapular rash
Bone marrow suppression
What do you do is patient develops macropapular rash?
Generic antihistamine
What do patients on carbimazole need to look out for?
Signs + symptoms of blood dyscrasis - FATAL
What are the signs + symptoms of blood dyscrasias?
ANY SYMPTOMS = STOP MEDICATION
Sore throat
Bruising
Bleeding
Mouth ulcers
Fever
Malaise
What should be done to prevent blood dyscrasias?
Full blood count every 6 months
What are the contraindications of carbimazole?
Severe hepatic impairment
pre-existing blood disorders
History of pancreatitis (check amylase)
What is the counselling for carbimazole?
Need for additional medications for symptoms
6-8 weeks to work
Urgency of reporting symptoms of blood dyscrasias
Start contraception = teratogenic
Intensify effects of warfarin
What is the mechanism of action of propylthiouracil?
Inhabitation of enzyme peroxidase
What is propylthiouracil used for?
2nd line for contraindications/side effects/with carbimazole/pregnancy
What are the side effects of propylthiouracil?
Macropapular rash
Severe hepatic reaction
Bone marrow suppression
What are the contraindications of propylthiouracil?
Hepatic impairment
Pre-existing blood disorders
History of pancreatitis
What is the monitoring for propylthiouracil?
Every 6 weeks (TSH, T4, T3) till in reference range
THEN every 3 months until complete
What is the aim of radioactive iodine?
Resolve hyperthyroidism without post-ablation hypothyroidism
What are the physician choices for radioactive iodine?
Fixed dose
Adjusted dose dependent on size of thyroid
Adjusted dose to administer specific dose of radiation
What problem with radioactive iodine?
Radioactive for up to 6 weeks
14 days after = no close contact
Avoid contact with pregnant women + children for 24 days
How long must thionamides be stopped before radioactive iodine?
1 week prior
How long will radioactive iodine take to have an effect?
2-3 months
What happens in severe cases?
Antithyroid medications restarted 3 days post op
Normally safe not to restart
What is the monitoring for radioactive iodine?
Measure TSH every 6 weeks until within reference range
Stop antithyroid medication once in range
When is a thyroidectomy vital?
Symptoms of windpipe compression
What is the surgical intervention of SND?
Partial or hemi-thyroidectomy
What is the surgical intervention of MND?
Dependent on nodule effected
What must you start post-thyroidectomy?
1.6mcg/kg levothyroxine immediately after
What is a hyperthyroid crisis?
Manifestation of thyrotoxicosis = overproduction of thyroid hormones
What are the symptoms of thyroid crisis?
Hyperthermia
Dehydration
Tachycardia (>140bpm)
Atrial dysrhythmias
Hypotension
Sweating
N/V/D/abdominal pain
Confusion/agitation
What are the 4 mechanisms of treatment for thyroid crisis?
Inhibition of thyroid hormone synthesis
Inhibition of thyroid hormone release
Inhibition of peripheral action of excess thyroid hormone
Supplementary management
What is used for inhibition of thyroid hormone synthesis for thyroid crisis?
20-30mg carbimazole every 4-6hrs
Oral/NG/rectal
What is used for inhibition of thyroid hormone release for thyroid crisis?
Iodine
BUT need to leave at least an hour between anti thyroid medication + iodine
What is used for the inhibition of peripheral hormone action for thyroid crisis?
Propranolol IV 1-2mg every 15mins until HR controlled
MAX 10mg
Cardioselective if COPD or asthma
What is used for supplementary management for thyroid crisis?
Paracetamol = antipyretic effects
Cholestyramine 4g every 6-12hrs = enhance thyroid hormone excretion