Grave's Disease Flashcards
What is Grave’s disease?
Graves’ disease is an autoimmune thyroid condition associated with hyperthyroidism.
Briefly describe the pathophysiology of Grave’s disease
Graves’ disease is an autoimmune condition.
The aetiology of thyroid hormone overproduction is stimulation of the thyroid by TSH receptor antibodies. Thyroid-stimulating immunoglobin (TSI) antibody binds to TSH and acts as an analogue.
Briefly describe Grave’s orbitopathy
Clinically present in around 25% of patients and is usually mild.
Upper eyelid retraction is present in over 90% of cases. The presence of upper eyelid retraction with thyroid dysfunction, exophthalmos/optic neuropathy, and/or extraocular muscle involvement is diagnostic of Graves’ orbitopathy.
What risk factors are associated with Grave’s disease?
- Family history
- Female sex
What are the signs of Grave’s disease?
- Diffuse goitre
- Orbitopathy
- Moist, velvety skin
What are the symptoms of Grave’s disease?
- Heat intolerance
- Sweating
- Weight loss
- Palpitations
- Irritability
- Scalp hair loss
- Muscle weakness
What are the clinical features of Grave’s orbitopathy?
- Eye irritation, photophobia or excessive watering of the eyes
- Redness of the eyes or eyelids and/or lid swelling
- Change in the appearance of the eye or eyelids:
- Eyelid retraction
- Lid lag
- Proptosis
- Persistent double vision in any direction of gaze
- Unexplained deterioration in visual acuity
What investigations should be ordered for Grave’s disease?
- TSH
- Serum free or total T3
- Serum free or total T4
- Calculation of total T3/T4 or T3/T4 ratio
- TSH receptor antibodies (TRAb)
Why investigate TSH? And what may this show?
- Initial screening test
- Suppressed
Why investigate serum free or total T3? And what may this show?
- Elevated free T3 and suppressed TSH suggest hyperthyroidism, even if the free T4 is normal. Order if TSH suggests hyperthyroidism but free T4 is normal, to differentiate clinical hyperthyroidism (T3 toxicosis) from subclinical hyperthyroidism.
- Elevated
Why investigate serum free or total T4? And what may this show?
- A normal level in the presence of low TSH is suggestive of subclinical hyperthyroidism or T3 toxicosis. An elevated level in the presence of a low TSH indicates overt hyperthyroidism. Order the test initially for diagnosis and also along with serum TSH for monitoring therapy.
- Elevated, except in T3 toxicosis or subclinical disease
Why investigate calculation of total T3/4 or T3/T4 ratio? And what may this show?
- May be helpful in distinguishing thyroiditis from Graves’ disease and toxic nodular goitre when the radioiodine uptake test is contraindicated (e.g., in pregnancy or lactation). A high T3/T4 ratio is suggestive of Graves’ disease rather than thyroiditis.
- Likely to be high compared with thyroiditis
Why investigate TSH receptor antibodies (TRAb)? And what may this show?
- It is used as a diagnostic test for Graves’ disease, particularly in questionable cases. Positive in 95% of patients with Graves’ disease.
- Positive
Briefly describe the treatment of Grave’s disease
Antithyroid drugs, radioactive iodine, and surgery are all effective and relatively safe options for treating Graves’ hyperthyroidism.
Beta-adrenergic blockers are used until specific therapy normalises peripheral thyroid hormone levels.
Briefly describe the use of antithyroid drugs in Grave’s disease
Antithyroid drugs are used in two ways:
- For a prolonged period of time (typically 12-18 months) to control the hyperthyroidism with the hope that the underlying autoimmune process will go into remission
- As adjunctive therapy to normalise thyroid function before surgery or radioiodine (when necessary)
These drugs block thyroid hormone synthesis. The group includes carbimazole, thiamazole, and propylthiouracil (PTU).