Definition:
This is the commonest cause of hyperthyroidism and is due to autoimmune process in which serum IgG antibodies bind to the thyroid TSH receptors and produce stimulation of thyroid hormone production, behaving like TSH.
Clinical features
Increased size and secretion of thyroid gland
GIT features include weight loss despite normal or increased appetite
Diarrhea
Anorexia
Vomiting
CVS
Palpitation
Sins tachycardia
Atrial fibrillation
Respiratory features
Increased pulse pressure
Dyspnea on exertion
Neuromuscular features
Nervousness
Irritability
Emotional liability
Tremor of hand
Muscle weakness
Dermatological features
Increased sweating
Palmar erythema
Pigmentation
Finger clubbing periorbital myxedema
Ocular
Exophthalmos
Corneal ulceration
Excessive lacrimation
Grittiness
Lid retraction
Lid lag
Chemosis
Ophthalmoplegia
Diplopia
Papilledema
Loss of visual acuity
Other
Heat intolerance
Fatigue
Thirst
Lymphadenopathy
Treatment
- Antithyroid drugs
- Subtotal thyroidectomy
- Radioactive iodine
Methimazole
An active derivative metabolite of carbimazole and propylthiouracil .these drugs act by reducing the synthesis thyroid hormone by inhibiting the iodinization of thyroxin.
Dose: 30-40 mg of methimazole or 300-400 mg of PTU are given until patient is euthyroid.
Improvement occurs in few weeks to months and then lower the dose that maintain euthyroidism and drug should be continued for 12-18 months.
Adverse effects:
Skin rash, agranlocytosis
Subtotal thyroidectomy
Peoperatve preparation
Operation in a thyrotoxic patient risk the thyroid storm so first treat the patient with antithyroid drugs to return them to euthyroid state before surgery.
Pros
Increase success rate
Rapid cure of hyperthyroid state
Cons
Hospitalization
Surgical and anesthesia side effects
Complications
Hypothyroidism
Recurrent laryngeal nerve paralysis
Postoperative bleeding
Radioactive iodine
A singe dose of iodine 131 I cause a decrease function and size of thyroid gland in 6-12 weeks.
Approx 75 % of patients are made euthyroid by a single dose. Eventually, almost all patients cured in this way.
Cons
Multiple doses may be needed
Hypothyroidism