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Thyrotoxicosis

Background knowledge ๐Ÿง 

Definition

  • Thyrotoxicosis refers to the clinical syndrome of excess thyroid hormones in the bloodstream.
  • Most commonly due to hyperthyroidism but can occur without increased thyroid gland activity.

Epidemiology

  • Prevalence: 2-5% of the UK population.
  • More common in women (5-10:1 female to male ratio).
  • Incidence increases with age.

Aetiology and pathophysiology

  • Graves’ disease (most common cause).
  • Toxic multinodular goitre.
  • Toxic adenoma.
  • Thyroiditis (subacute, postpartum).
  • Excessive thyroid hormone intake (exogenous).
  • Amiodarone-induced thyrotoxicosis.

Types

  • Overt thyrotoxicosis: Clinical and biochemical hyperthyroidism.
  • Subclinical thyrotoxicosis: Low TSH with normal free T4 and T3 levels.
  • Thyroid storm: Severe, life-threatening thyrotoxicosis.

Clinical Features ๐ŸŒก๏ธ

Symptoms

  • Weight loss despite increased appetite.
  • Heat intolerance and excessive sweating.
  • Palpitations.
  • Nervousness, irritability, and anxiety.
  • Tremor.
  • Fatigue and muscle weakness.
  • Increased bowel movements or diarrhoea.

Signs

  • Tachycardia or atrial fibrillation.
  • Warm, moist skin.
  • Goitre.
  • Lid lag and lid retraction.
  • Hyperreflexia.
  • Proximal muscle weakness.
  • Eye signs in Graves’ disease:
    • Proptosis.
    • Periorbital oedema.

Investigations ๐Ÿงช

Tests

  • Thyroid function tests (TFTs): Low TSH, high free T4 and T3.
  • TSH receptor antibodies (TRAb) for Graves’ disease.
  • Thyroid peroxidase antibodies (TPOAb) and thyroglobulin antibodies (TgAb) for autoimmune thyroiditis.
  • Radioactive iodine uptake scan to differentiate causes.
  • Ultrasound of thyroid for structural assessment.
  • ECG if arrhythmia is suspected.

Management ๐Ÿฅผ

Management

  • Antithyroid drugs (carbimazole or propylthiouracil).
  • Radioactive iodine therapy.
  • Surgical intervention (thyroidectomy) in selected cases.
  • Beta-blockers (e.g., propranolol) for symptomatic relief.
  • Monitor TFTs regularly to adjust treatment.
  • Patient education and support.

Complications

  • Thyroid storm.
  • Atrial fibrillation.
  • Osteoporosis.
  • Heart failure.
  • Graves’ orbitopathy.
  • Hypothyroidism post-treatment.

Prognosis

  • Most patients respond well to treatment.
  • Risk of recurrence in Graves’ disease.
  • Lifelong monitoring may be necessary.
  • Potential for long-term complications if not adequately managed.

Key points

  • Early diagnosis and treatment are essential.
  • Thorough clinical assessment and appropriate investigations.
  • Individualized treatment plans.
  • Regular follow-up to monitor response and adjust therapy.
  • Educate patients about their condition and treatment options.

References

  • NICE Guidelines: Hyperthyroidism (https://www.nice.org.uk/guidance/ng145) NICE Guidelines
  • British Thyroid Association: Management of Thyrotoxicosis (https://www.british-thyroid-association.org) BTA Guidelines

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