Hyperthyroidism is a condition in which an overactive thyroid gland is producing an excessive amount of thyroid hormones that circulate in the blood. Graves' disease, multinodular goiter (TMNG), inflammation of the thyroid gland (thyroiditis) and excessive iodine intake are the most common cause of hyperthyroidism.

Risk Factors

• Female sex

• Age 20–50 years (Graves’ common)

• Family history of thyroid disease

• Autoimmune disorders

• Postpartum period

• Excess iodine exposure (contrast, medications e.g amiodarone)

• Previous thyroid nodules

• Smoking (especially Graves’ ophthalmopathy)

Signs and Symptoms

General

• Weight loss despite increased appetite

• Heat intolerance

• Excess sweating

• Fatigue

Neurological

• Tremors

• Anxiety, irritability

• Hyperreflexia

• Insomnia

Skin and Hair

• Smooth velvety skin

• Fine hair

• Hair thinning

Cardiovascular

• Palpitations

• Tachycardia

• Atrial fibrillation

• Systolic hypertension

Gastrointestinal

• Frequent bowel movements

• Diarrhoea

Thyroid

• Enlarged thyroid gland (goitre)

Specific to Graves’ disease

• Eye signs (ophthalmopathy)

• Pretibial myxedema (rare)

Diagnostic Criteria

Hyperthyroidism should be suspected in patients presenting with:

• Tremors

• Excessive sweating

• Smooth velvety skin

• Fine hair

• Rapid heart rate

• Enlarged thyroid gland

• Frequent bowel movement

Definitive diagnosis:

• ↓ TSH (suppressed)

• ↑ Free T4 and/or T3

Investigations

• Baseline complete blood count, including white count with differential, and a liver profile (bilirubin and transaminases)

• Differential white blood cell count should be obtained during febrile illness and at the onset of pharyngitis in all patients taking antithyroid medication. Routine monitoring of white blood counts is not recommended

• Test for THS and T4

• When thyrotoxicosis is confirmed, if cause is not known request thyroid uptake scan

Note: Management of hyperthyroidism depends on the cause

Management

Note: Management of hyperthyroidism depends on the cause

Toxic Multinodular Goitre or Thyroid Antibody Positive

Patients with overtly Toxic multinodular goitre or Thyroid antibody are treated with either:

• Radio iodine (131-I) therapy

• Thyroidectomy

Note: Long term, low-dose carbimazole should not be used for either conditions except in some elderly

Surgery

• Patients with overt hyperthyroidism should be rendered euthyroid prior to the procedure with carbimazole pre-treatment (15–40 mg daily, divided into 2–3 doses a day for 4–8 weeks then a maintenance dose of 5–15 mg, taken once daily) with or without beta–adrenergic blockade (e.g. propranolol 1–40 mg every 6 hours). Preoperative iodine should not be used in this setting.

• Following thyroidectomy for Toxic multinodular goitre, it is suggested that serum calcium or intact parathyroid hormone levels be measured, and that calcitriol and oral calcium supplementation (maximum 1,200 mg of calcium per day in two divided doses) be administered based on these results.

• Following surgery for Toxic multinodular goitre, thyroid hormone replacement should be started at a dose appropriate for the patient’s weight (0.8 µg/lb or 1.7 µg/kg) and age, with elderly patients needing somewhat less. TSH should be measured every 1–2 months until stable, and then annually.

Radioiodine

• Radioactive iodine therapy should be used for retreatment of persistent or recurrent hyperthyroidism following inadequate surgery for Toxic multinodular goitre or Thyroid antibody.

Refers to picture 1: Graves hyperthyroidism

Beta Blockers

Beta Blockers are used for excessive sympathetic symptoms:

• Atenolol (PO) 50–100 mg daily

Factors Which Favour Use of Antithyroid Medicines

• High likelihood of remission (patients, especially females, with mild disease, small goitres, and negative or low-titre TSH-receptor antibody)

• Elderly or others with comorbidities increasing surgical risk or with limited life expectancy or unable to follow radiation safety regulations

• Previously operated or irradiated necks

• Moderate to severe active Graves’ ophthalmopathy

Radioactive Iodine (Pre-operative Use)

• Potassium iodide (B) should be given in the immediate preoperative period as 5–7 drops (0.25–0.35 mL) Lugol’s solution (8 mg iodide/drop) or 1–2 drops (0.05–0.1 mL) saturated solution of potassium iodide (50 mg iodide/drop) three times daily mixed in water or juice for 10 days before surgery

Factors Which Favour Use of Radioiodine

• Individuals with comorbidities increasing surgical risk

• Patients with previously operated or externally irradiated necks

• Lack of access to a high-volume thyroid surgeon

• Contraindications to antithyroid medicines use

• Females who are not pregnant and are not planning a pregnancy in the future (4–6 months) following radioiodine therapy

Surgery

• Consider the following factors

• Symptomatic compression or large goitres

• Low uptake of radioactive iodine

• Thyroid malignancy is documented or suspected or large non-functioning nodule

• Coexisting hyperparathyroidism requiring surgery

• Females planning a pregnancy in <4–6 months

• Patients with moderate to severe active Graves’ ophthalmopathy

• If a patient with Grave’s disease becomes hyperthyroid after completing a course of carbimazole, consideration should be given to treatment with radioactive iodine or thyroidectomy.

• Low-dose carbimazole treatment for longer than 12–18 months may be considered in patients not in remission prefer this approach but evidence is that remission rate in adults is not improved by a course of medicines longer than 18 months

• Whenever possible, patients with Grave’s disease undergoing thyroidectomy should be rendered euthyroid with carbimazole.