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Hyperthyroidism

Jan 14, 20243 min read

Hyperthyroidism is a medical condition characterized by excessive production of thyroid hormones by the thyroid gland. There are various underlying causes of hyperthyroidism, with the most common being Grave’s disease.

Hyperthyroidism is increased thyroid hormone synthesis and secretion from the thyroid gland. Thyrotoxicosis is the clinical syndrome of excess circulating thyroid hormones irrespective of source. Hyperthyroidism is a subset of thyrotoxicosis

Causes/Factors

GIST mnemonic

  • Graves’ disease - Inflammation (thyroiditis)
  • Solitary toxic thyroid nodule. Usually benign adenomas that require surgical removal
  • Toxic multinodular goitre

Info

Thyroiditis can often cause an initial period of hyperthyroidism followed by hypothyroidism.

Symptoms

  • Anxiety and irritability
  • Sweating and heat intolerance
  • Tachycardia
  • Weight loss
  • Fatigue
  • Insomnia
  • Frequent loose stools
  • Sexual dysfunction
  • Brisk reflexes on examination

Signs

  • Enlarged Thyroid Gland (Goiter): The thyroid gland may be visibly larger than normal, causing swelling in the front of the neck.
  • Tachycardia: Abnormally fast heart rate.
  • Exophthalmos: In Grave’s disease, patients may have protruding or bulging eyes due to immune system attack on the eye tissues.
  • Pretibial myxoedema discoloured waxy appearance over this area - specific to Grave’s disease

Diagnostic Tests

  • Thyroid Function Tests: Blood tests to measure levels of thyroid hormones (T3 and T4) and thyroid-stimulating hormone (TSH).
  • Radioactive Iodine Uptake (RAIU): Measures how much iodine the thyroid gland absorbs to determine its activity.
  • Thyroid Ultrasound: Imaging test using sound waves to visualize the size and structure of the thyroid gland.
  • Antibody Tests: To detect antibodies associated with Grave’s disease.

Radioactive iodine

  • Increased homogenous uptake - Grave’s disease
  • Area of intense uptake interspersed with reduce activity - toxic nodular goitre
  • Faint diffuse uptake - De Quervain’s Thyroiditis
  • No uptake at all - inflammatory conditions
  • Single hot node with the rest of the gland suppressed - toxic adenoma

Management

  • Carbimazole is the first line anti-thyroid drug. Two treatment options:
    1. The Carbimazole dose is titrated to maintain normal levels
    2. A higher dose blocks all production and Levothyroxine is added and titrated to effect
    3. Risk of agranulocytosis and acute pancreatitis

Warning

The MHRA issued a warning in 2019 about the risk of acute pancreatitis in patients taking Carbimazole. In exams, look out for a patient on Carbimazole presenting with symptoms of pancreatitis (e.g., severe epigastric pain radiating to the back).

  • Propylthiouracil is second line and works in the same way. Small risk of severe liver reaction.

Both can cause agranulocytosis - this makes people vulnerable to infection. A Sore throat is a key presenting feature. Need an urgent FBC and aggressive treatment.

  • Beta blockers - propanolol is usual as its non-selectively blocks adrenergic activity.

Surgery is definitive option - removing the whole thyroid gland and starting life-long Levothyroxine

Complications/Red Flags

  • Thyroid Storm: It is a rare and more severe presentation of hyperthyroidism with fever, tachycardia and delirium. It can be life-threatening and requires admission for monitoring.
  • osteoporosis: Long-term hyperthyroidism can lead to Bone loss and an increased risk of fractures.
  • Heart Problems: Untreated hyperthyroidism can strain the heart, leading to heart rhythm abnormalities and potential Heart Failure.
  • Pregnancy Complications: Hyperthyroidism during Pregnancy requires careful management to prevent harm to both the mother and the baby.

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