Endocrine - Hyperthyroidism Flashcards
What is Thyrotoxicosis?
Excessive quantity of thyroid hormones
What is primary hyperthyroidism?
Thyroid pathology causing excessive thyroid hormone
High T3/4
Low TSH
What is secondary hyperthyroidism?
Pathology in hypothalamus or pituitary
High TSH
High T3/4
What is subclinical hyperthyroidism?
T3 and T4 are normal
TSH is low
What is Grave’s disease?
TSH receptor autoantibodies
Stimulates TSH receptors to release thyroid hormones
What is a toxic multinodular goitre?
AKA Plummer’s disease
Nodules develop on thyroid gland causes continuous production of excessive thyroid hormones
What causes exophthalmos in Grave’s disease?
Cytokine production due to autoantibodies
Cytokines stimulate synthesis of glycosaminoglycans (GAGs) by fibroblasts
GAGs attract water
Causes periorbital oedema, proptosis and swelling extraocular muscles
What is pretibial myxoedema caused by?
Deposits of glycosaminoglycans under skin on anterior aspect of the leg
Specific to Grave’s disease reaction to TSH receptor antibodies
Can also occur in Hashimoto’s thyroiditis but much rarer
What can cause hyperthyroidism?
Grave’s disease
Thyroiditis
Solitary toxic thyroid nodule
Toxic multinodular goitre
What are some causes of thyroiditis?
De Quervain’s thyroiditis
Hashimoto’s thyroiditis
Postpartum thyroiditis
Drug-induced thyroiditis
How does hyperthyroidism present?
Anxiety and irritability
Sweat and heat intolerance
Tachycardia
Weight loss
Fatigue
Insomnia
Sexual dysfunction
What specific features are caused by Grave’s disease?
Diffuse goitre
Exophthalmos
Pretibial myxoedema
Thyroid acropachy (hand swelling and finger clubbing)
What is a solitary toxic thyroid nodule?
Single abnormal thyroid nodule releases excessive thyroid hormone
Nodules are benign adenomas
Surgical removal to treat
What is De Quervain’s Thyroiditis?
AKA subacute thyroiditis
Condition causing temporary inflammation of the thyroid gland
Three phases:
- Thyrotoxicosis
- Hypothyroidism
- Return to normal
What does the initial thyrotoxic phase involve?
Excessive thyroid hormones
Thyroid swelling and tenderness
Flu-like illness
Raised inflammatory markers (CRP and ESR)
How do you treat De Quervain’s thyroiditis?
NSAIDs
Beta blockers for symptoms of hyperthyroidism
Levothyroxine for symptoms of hypothyroidism
What is a thyroid storm/ thyrotoxic crisis?
Severe presentation of hyperthyroidism with
- Fever
- Tachycardia
- Delirium
May need fluid resuscitation, anti-arrhythmics and beta blockers
How do you manage hyperthyroidism?
First-line
Carbimazole 12-18 months
After 4-8 weeks thyroid levels will be normal
Carbimazole is continued on maintenance and either:
- Carbimazole dose titrated to maintain normal levels
- Higher dose to block all production and levothyroxine given (block and replace)
Second-line
Propylthiouracil
Small risk of severe liver reactions so carbimazole is preferred
What can carbimazole cause?
Acute pancreatitis
What can carbimazole and propylthiouracil cause?
Agranulocytosis with extremely low WBC
Sore throat key sign of agranulocytosis
How does radioactive iodine treatment work?
Thyroid takes up radioactive iodine
Emitted radiation destroys proportion of thyroid cells
Reduction in number of cells decreasing thyroid production
Remission can take 6 months
Why do you give long-term levothyroxine after radioactive iodine treatment?
Thyroid becomes underactive
What strict rules are there with radioactive iodine treatment?
- Women must not be pregnant or breastfeed and get pregnant within 6 months of teatment
- Men cannot father children within 4 months
- Limit contact with people after the dose
Why is propranolol preferred to bisoprolol for treating adrenaline-related symptoms of hyperthyroidism?
Non-selectively blocks adrenergic activity
Bisoprolol is more selective
Particularly useful for thyroid storm management
What is the final treatment option for hyperthyroidism?
Thyroidectomy
Patients require life-long levothyroxine after
