Hyperthyroidism & Subclinical Hyperthyroidism Flashcards
What is the most common cause of thyrotoxicosis?
Grave’s disease (50-60%)
What are the most common causes of thyrotoxicosis?
- Graves’ disease
- Toxic nodular goitre
- Subacute (de Quervain’s) thyroiditis (self limiting)
- Post-partum thyroiditis (Usually self limiting - may requre intervention)
- Acute phase of Hashimoto’s thyroiditis (later results in hypothyroidism)
- Toxic adenoma (Plummer’s disease)
- Amiodarone therapy
What gender and age group is Grave’s disease most commonly seen?
- Women aged 30-50 years
What are some features of Grave’s disease that aren’t seen in other causes of thyrotoxicosis?
- Eye signs (30% of patients): Exopthalmos, ophthalmoplegia.
- Pretibial myxoedema
- Thyroid acropachy (clubbing)
What autoantibodies are raised in Grave’s disease?
Anti-TSH receptor stimulating antibodies (90%)
Anti-thyroid peroxidase antibodies (50%)
NOTE: these are expensive and generally not used but only used in pregnant women.
What are the majority of autoantibodies are seen in what autoimmune thyroid conditions?
Autoimmune hyperthyroidism - Grave’s disease - Anti-TSH receptor stimulating antibodies
Autoimmune hypothyroidism
-
Hashimoto’s Thyroiditis (most common cause in the west with Iodine rich diets)
- (Hyperthyroidism –> hypothyroidism) - Anti-thyroid peroxidase antibodies
What 2 drugs can cause hyperthyroidism?
Lithium
Amiodarone
What radiology test can be done in hyperthyroidism if the diagnosis is in doubt?
- Consider iodine uptake scan
- Low uptake suggests thyroiditis (which is usually self-limiting)
- High uptake suggests Graves’ disease
- Patchy uptake can suggest a nodule.
Describe the treatment strategies for Grave’s disease?
- Propanolol - to initially block adrenergic effects.
-
Anti-thyroid drug- Block & Titrate (Relpase rate 50%)
- Start Carbimazole at 40mg and gradualy reduce whilst maintaining euthyroidism.
- Typically continued for 8 to 12 months.
- Fewer side effects than those on block-and-replace regimes.
-
ATD - Block-and-replace (Relpase rate 50%)
- Start Carbimazole at 40mg.
- Thyroxine is added when the patient is euthyroid.
- Treatment is typically for 6 to 9 months.
- Radioiodide therapy (Usually for relapsed Grave’s disease)
- Surgery
What is a complication of carbimazole therapy?
Agranulocytosis
- Give all patients starting antithyroid drugs written information about agranulocytosis
- they must seek an urgent FBC in the event of sore throat or fever.
What are the contraindications for radioiodine therapy?
- Contraindications include pregnancy (should be avoided for 4-6 months following treatment) and age < 16 years.
- Thyroid eye disease is a relative contraindication, as it may worsen the condition.
After how many years will the majority of patients require thyroxine supplementation after having had radioiodide therapy?
5 years
How do you know if someone has subclinical hyperthyroidism.
- Normal T4/T3
- Low TSH.
What are the causes of Subclinical hyperthyroidism?
- Multinodular goitre, particularly in elderly females
- Excessive thyroxine may give a similar biochemical picture
What medical conditions can subclinical hyperthyroidism lead to?
- AF
- Osteoporosis
- Increases likelihood of dementia
