Hyperthyroidism Flashcards
Which antibodies might be present in thyroid disease?
Anti-thyroid peroxidase (anti-TPO) antibodies
Anti-thyroglobulin antibodies
TSH receptor antibodies
When might anti-TPO antibodies be present?
Grave’s disease
Hashimoto’s thyroiditis
When might anti-thyroglobulin antibodies be present?
Grave’s disease
Hashimoto’s thyroiditis
Thyroid cancer
–> may be present in normal individuals so measuring them is of limited use
When might TSH receptor antibodies be present?
They are the cause of Grave’s Disease
Which modalities of imaging are used in thyroid disease?
US of thyroid
Radioisotope scan
When is US useful for thyroid disease?
Diagnosing thyroid nodules
- distinguishing between cysts (fluid filled) + solid nodules
Guiding biopsy of a thyroid lesion
When is a radioisotope scan used in thyroid disease?
Investigating hyperthyroidism + thyroid cancers
How does a radioisotope scan work?
Patient given radioactive iodine orally or IV
The most active the thyroid cells, the faster the iodine is taken up
Gamma camera used to detect gamma rays emitted from the radioactive iodine
–> functional thyroid information
What might be seen on radioisotope scan indicating what pathology?
Diffuse uptake –> Grave’s
Focal high uptake –> toxic multi nodular goitre + adenomas
Cold areas (low uptake) –> thyroid cancer
What are the causes of primary hyperthyroidism?
Grave's disease Toxic multinodular goitre Solitary toxic thyroid nodule Thyroiditis: - De Quervain's - Hashimoto's - postpartum - drug-induced
What is Grave’s disease?
Autoimmune condition
TSH receptor antibodies mimic TSH
Most common cause of hyperthyroidism
What is toxic multi nodular goitre?
aka Plummer’s disease
Nodules on thyroid gland that act independently of the normal feedback system –> continuous production of excessive thyroid hormone
What are the universal features of hyperthyroidism?
Anxiety + irritability Sweating + heat intolerance Tachycardia Weight loss Fatigue Frequent loose stools Sexual dysfunction
What are the unique features of Grave’s disease?
(due to TSH receptor antibodies)
- diffuse goitre (without nodules)
- Graves eye disease
- bilateral exophthalmos
- pretibial myxoedema
What is pretibial myxoedema?
Deposits of mucin under the skin on anterior leg –> discoloured, waxy, oedematous appearance
What are the features of toxic multi nodular goitre?
Goitre with firm nodules
Patients over 50
Second more common cause of thyrotoxicosis (after Grave’s)
What are the features of a solitary toxic thyroid nodule?
Single abnormal nodule releasing thyroid hormone
Usually a benign adenoma
Treated with surgical removal of the nodule
What are the features of De Quervain’s thyroiditis?
Viral infection with:
- fever
- neck pain + tenderness
- dysphagia
- features of hyperthyroidism
- -> followed by hypothyroid phase
How is De Quervain’s thyroiditis treated?
NSAIDs for pain + inflammation
Beta-blockers for symptomatic relief of hyperthyroidism
(self-limiting)
What is thyroid storm and what are the presenting features?
Rare presentation of hyperthyroidism, aka thyrotoxic crisis
- pyrexia
- tachycardia
- delirium
What is the first line treatment for hyperthyroidism?
Carbimazole
How is the dose or carbimazole adjusted?
Once patient has normal thyroid hormone levels, continue on maintenance carbimazole and either:
- titrate dose to maintain normal levels
- dose is sufficient to block all production + patient takes levothyroxine (block + replace)
Do patients need to take carbimazole long term?
Patients can usually stop after 18 months of treatment
What is the second line antithyroid drug?
Propylthiouracil
- small risk of severe hepatic reactions so carbimazole is preferred
What are the other options for management of hyperthyroidism?
Radioactive iodine
Surgical removal of thyroid gland or toxic nodules
How does radioactive iodine work?
Patient drinks single dose of radioactive iodine
Taken up by thyroid + emitted radiation destroys a proportion of the thyroid cells
–> decrease in hormone production
May be left hypothyroid (need to take levothyroxine)
What are the rules around radioactive iodine?
Must not be pregnant, and cannot get pregnant for 6 months after treatment
Must avoid contact with children + pregnant women for 3 weeks (depends on dose)
Limit contact with anyone for several days after treatment
Which drug might be used to treat the symptoms of hyperthyroidism?
Beta-blockers –> propranolol
- block adrenaline related symptoms
- particularly useful in thyroid storm
