Hyperthyroidism

• 1st line treatment for graves disease is carbimazole

  Re-check bloods in 2-3 weeks

  Carbimazole is highly teratogenic so patient must be on contraception

  Once euthyroidism is achieved, carbimazole can be titrated or swap to a block and replace regime
• Radioiodine is a definitive management for graves disease and toxic multinodular goitre. Not suitable in pregnancy or malignancy.

  Female patients must be advised against becoming pregnant within 6 months and men against fathering children for the next 4 months

  Can result in hypothyroidism
• Thyroidectomy is indicated in cases of thyroid malignancy or where a goitre is causing compression of surrounding structures

  Will need to be on life long thyroid hormone replacement therapy - levothyroxine
• A serious complication of thyrotoxicosis is the onset of a thyroid storm, which involves excessive adrenergic activity secondary to thyrotoxicosis. 
• Clinical features of a thyroid storm may include:

  • Palpitations
  • Tachycardia (often greater than 140 beats per minute)
  • Tremor
  • Nausea and vomiting
  • Abdominal pain
  • Reduced level of consciousness
  • Confusion/agitation
  • Seizures

  Thyroid storm is associated with high mortality.
• Cardiac complications of thyrotoxicosis:

  • Atrial fibrillation
  • Heart failure
  • Angina
• A thyroid storm can be a result of untreated/undertreated hyperthyroidism, or it can be a result of an intercurrent illness
• Treatment of a thyroid storm:

  • Anti-thyroid treatment - propylthiouracil PO/NG/PR
  • After 4 hours give Lugol's solution- iodine solution
  • IV injection propranolol
  • IV hydrocortisone followed by prednisolone - prevents peripheral conversion of T4 to T3
• Thyrotoxicosis is the clinical manifestation of excess thyroid hormone action at the tissue level due to inappropriately high circulating thyroid hormone concentrations.

  Hyperthyroidism is a subset of thyrotoxicosis, referring specifically to excess thyroid hormone synthesis and secretion by the thyroid gland. 
• The most common cause of thyrotoxicosis is Graves’ disease, an autoimmune condition that results in excess endogenous production of thyroid hormones.
• Graves’ disease is the most common cause of thyrotoxicosis and hyperthyroidism. This is an autoimmune condition mediated via anti-TSH-Receptor (anti-TSHR) autoantibodies.

  These autoantibodies bind to TSH-receptors on the thyroid gland and stimulate increased production of T3 and T4 from the thyroid gland, resulting in thyrotoxicosis.
• Graves disease typically presents in patients between the ages of 40 and 60, and is much more common in female patients. Graves’ disease is also strongly associated with other auto-immune conditions including type 1 diabetes mellitus, Addison’s disease and vitiligo
• Toxic multinodular goitre (TMG) is caused by the development of physiologically active nodules on the thyroid gland, which are capable of secreting thyroid hormones. These nodules are not responsive to circulating TSH concentrations and so, eventually cause thyrotoxicosis. It is the second most common cause of hyperthyroidism and commonly affects older patients.
• Excess serum iodine concentrations can also cause thyrotoxicosis. This is because thyroid hormone production is dependent upon iodine, so increased serum iodine concentrations allow increased production of the hormones.

  Iodine excess can occur following the use of contrast media for imaging modalities or via the contamination of food
• Iatrogenic causes of thyrotoxicosis include the drugs amiodarone and levothyroxine.

  Amiodarone contains iodine and increases iodine levels
• Viral infections can predispose to a phenomenon known as ‘subacute De Quervain’s thyroiditis’. This can cause a transient rise in thyroid hormone production due to inflammation of the thyroid gland and subsequent excessive excretion of thyroid hormones into the circulation. subacute De Quervain’s thyroiditis presents with a painful lump in the neck.

  Patients may subsequently develop hypothyroidism if the thyroid gland tissue is damaged by the inflammation.
• Postpartum thyroiditis presents with a transient acute phase of thyrotoxicosis, followed by a period of hypothyroidism. This can occur 2 – 6 months following birth or miscarriage.
• Typical symptoms of thyrotoxicosis include:

  • Recent unintended weight loss
  • Increased appetite
  • Diarrhoea
  • Heat intolerance (patients may appear underdressed for the weather)
  • Over-activity and restlessness
  • Tremor
  • Palpitations
  • Irritability
  • Muscle weakness
  • Loss of libido
  • Oligomenorrhoea
• Clinical features of thyrotoxicosis may include:

  • Thin and brittle hair
  • Warm and moist skin
  • Irregular or fast heart rate
  • Fine tremor
  • Brisk reflexes
  • Palmar erythema
  • Lid lag and lid retraction
  • Goitre (enlargement of the neck due to an enlarged thyroid gland)
• There are some clinical features of thyrotoxicosis which are specific to Graves’ disease, due to the presence of the anti-TSHR autoantibodies.

  Clinical features of Graves’ disease may include:

  • Graves ophthalmopathy - exophthalmos, conjunctival injection and aching in the back of the eye
  • Thyroid acropachy
  • Pretibial myxoedema
• Thyroid function tests in primary hyperthyroidism:

  • Decreased TSH
  • Increased T3 and T4
• If thyrotoxicosis is due to a rarer pituitary cause:

  • Increased TSH
  • Increased T3 and T4
• The presence of thyroid autoantibodies suggests there is an underlying autoimmune disease causing thyrotoxicosis. The presence of anti-TSHR antibodies is highly suggestive of Graves’ disease.
• Anti-TPO and anti-Tg antibodies also suggest an autoimmune cause of hyperthyroidism but will also be positive in Hashimotos disease
• Carbimazole is first line drug treatment for hyperthyroidism

  Propylthiouracil is first line in pregnancy

  Patients who are on these drugs and develop a sore throat they need an urgent FBC to check for agranulocytosis - white blood cell suppression
• Thyroid hormones are produced from the follicular cells of the thyroid gland
• Doppler ultrasound may be used to image the thyroid gland to confirm the presence of a goitre and identify any nodules
• After euthyroidism is achieved, a trituration block regime or block and replace regime is used
• Radioiodine is a definitive management option for Graves disease and toxic multinodular goitre

  If radioiodine is deemed unsuitable for patients with Graves’ disease (e.g. due to pregnancy or malignancy), block and replace therapy is typically used as a second-line management option.

  If radioiodine is deemed unsuitable for patients with a toxic multinodular goitre, thyroid surgery is used as a second-line management option.
• Thyroidectomy is indicated in cases of thyroid malignancy, or where a thyroid goitre is causing compression of surrounding structures. Thyroidectomy may also be considered if other treatment options are unsuitable or unsuccessful - will need to be on long term thyroid hormone replacement
• Beta-blockers (commonly propranolol) are indicated in the management of thyrotoxicosis to provide symptomatic relief from the typical adrenergic symptoms (palpitations, tachycardia, tremor)
• Radioactive iodine should not be used for graves disease if there is associated graves eye disease - can make worse