What is thyrotochisis?

Thyrotoxicosis: Definition and Management

Thyrotoxicosis refers to a clinical syndrome resulting from excessive circulating thyroid hormones, which may or may not be due to overproduction by the thyroid gland itself. It typically follows a triphasic pattern of initial hyperthyroidism, followed by hypothyroidism, and eventual restoration of normal thyroid function in many cases 1.

Types and Causes

• Thyrotoxicosis can result from hyperthyroidism (overproduction of thyroid hormones) or from inflammation of the thyroid gland (thyroiditis) with release of preformed hormones 1, 2
• Common causes include:
  • Thyroiditis (autoimmune, viral, radiation-induced, traumatic, or drug-induced) 3
  • Graves' disease (most common form of hyperthyroidism) 2
  • Toxic nodular goiter 2
  • Excessive ingestion of thyroid hormones ("thyrotoxicosis factitia") 4
  • Iodine-induced hyperthyroidism from contrast agents or medications 4
  • Drug-induced thyroiditis (amiodarone, immune checkpoint inhibitors, interleukin-2, interferon-alfa, lithium, tyrosine kinase inhibitors) 1, 4

Clinical Presentation

• Symptoms may include:
  • Weight loss, palpitations, heat intolerance, tremors, anxiety, diarrhea 5
  • Paradoxically, fatigue can be a prominent symptom despite the hypermetabolic state 6
  • In thyroiditis, anterior neck pain may be present (subacute thyroiditis) or absent (painless thyroiditis) 1
  • Exophthalmos and eyelid retraction may be present in Graves' disease 5

Diagnostic Approach

• Laboratory findings typically show:
  • Low or suppressed TSH 6
  • Elevated free T4 or T3 levels 5
  • In subclinical hyperthyroidism, TSH is suppressed with normal free T4 and T3 6
• Additional testing may include:
  • Thyroid antibodies (TPO, TRAb, TSI) to differentiate between thyroiditis and Graves' disease 5, 6
  • Radioactive iodine uptake scan (RAIUS) or Technetium-99m thyroid scan to distinguish hyperthyroidism from thyroiditis 5
  • Thyroid ultrasound to evaluate for nodules 7

Management

• Treatment depends on the underlying cause:

  • For thyroiditis-induced thyrotoxicosis:

    • Conservative management is usually sufficient as it's self-limiting 5
    • Non-selective beta blockers (preferably with alpha receptor-blocking capacity) for symptomatic relief 5
    • NSAIDs or corticosteroids for painful thyroiditis 1
    • Monitor thyroid function every 2-3 weeks as hypothyroidism may develop after the thyrotoxic phase 5

  • For Graves' disease or toxic nodular goiter:

    • Antithyroid drugs (12-18 month course for Graves' disease) 2
    • Radioactive iodine or surgery for toxic nodules or goiters 2
    • Beta blockers for symptom control 5

Follow-up and Monitoring

• Repeat thyroid function tests every 2-3 weeks during the acute phase 5, 6
• Monitor for progression to hypothyroidism, which commonly occurs 1-2 months after the initial thyrotoxic phase in thyroiditis 5, 6
• Consider levothyroxine therapy if hypothyroidism develops and is symptomatic or persistent 8
• Endocrinology consultation is recommended for all cases of confirmed thyrotoxicosis 5

Potential Complications and Pitfalls

• Thyroid storm is a rare but life-threatening complication requiring immediate treatment 4
• Iatrogenic thyrotoxicosis from medications requires identification and management of the offending agent 4
• Patients with adrenal insufficiency and thyrotoxicosis should receive steroid treatment before addressing thyroid dysfunction to avoid precipitating an adrenal crisis 7
• Thyroiditis is often misdiagnosed as Graves' disease, leading to inappropriate treatment with antithyroid drugs 1, 8