Hyperthyroidism

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Background

  • Hyperthyroidism: Excess circulating hormone resulting from thyroid gland hyperfunction
  • Thyrotoxicosis: Excess circulating thyroid hormone originating from any cause

Causes

Primary Hyperthyroidism

  • Graves disease (toxic diffuse goitre)
    • Most common cause of hyperthyroidism (85% of cases)
    • Autoantibodies bind to TSH receptor and stimulate thyroid hormone production and release [1]
    • Associated with diffuse goitre, ophthalmopathy, local dermopathy
    • Strong genetic relationship, often found with other autoimmune disorders [2]
  • Toxic multinodular goitre
    • 2nd most common cause
    • Multiple autonomously functioning nodules [3]
    • Milder, more gradual disease than Graves' hyperthyroidism
  • Toxic nodular (adenoma) goitre
    • Single hyperfunctioning nodule
    • Similar presentation to multinodular goitre, but less common [4]


Secondary Hyperthyroidism

  • Thyrotropin-secreting pituitary adenoma
  • Thyroiditis
    • Hashimoto thyroiditis
      • Autoimmune disorder
      • Thyroid antibodies and lymphocytic infiltration [5]
      • Painless goitre
      • Initially gland is overactive (hyperthyroidism state) followed by hypothyroidism
    • Subacute painful thyroiditis (de Quervain thyroiditis)[6]
      • May be caused by viral infection
      • Viral prodrome followed by anterior neck pain
      • Tender thyroid (palpation, head movement, swallowing)
      • 50% have symptoms of hyperthyroid lasting 3 - 6 weeks
      • 1/3 have hypothyroidism for up to 6 months
    • Subacute painless thyroiditis [7]
      • Small, non-tender goitre
      • Mild symptoms
      • Autoimmune
    • Postpartum thyroiditis [8]
      • 3 phases:
        • Thyrotoxic phase 2 -6 months postpartum (20-30% have only this phase)
        • Hypothyroid phase lasting 2 -3 months (but may be permanent) (40% have this phase only)
        • Euthyroid phase within first postpartum year
      • Some women develop permanent hypothyroidism
      • 70% recurrence in subsequent pregnancies
    • Suppurative thyroiditis [9]
      • Rare
      • Life-threatening
      • Infection usually bacterial, but can be parasitic, mycobacterial, or fungal
      • Usually have pre-existing thyroid disorder and immune compromise
    • Radiation thyroiditis

Other causes:

  • Apathetic thyrotoxicosis (elderly, masking comorbidities)
  • Metastatic thyroid cancer
  • Iodine-induced thyrotoxicosis
  • Amiodarone-induced thyroiditis [10]
    • Possible mechanisms:
      • Drug-induced destructive thyroiditis
      • Hyperthyroidism caused by iodine load (amiodarone contains a large amount of iodine)
    • Drug-induced thyroiditis may also occur with interleukin-2, interferon alpha, lithium, tyrosine kinase inhibitors, HAART
  • Molar pregnancy

Clinical Features

Constitutional signs:

  • Lethargy
  • Diaphoresis
  • Weakness
  • Fever
  • Heat intolerance
  • Weight loss

Neuropsychiatric:

  • Emotional lability
  • Fine tremor
  • Anxiety
  • Muscle wasting
  • Confusion
  • Hyperreflexia
  • Coma
  • Periodic paralysis
  • Psychosis

Ophthalmologic:

  • Diplopia
  • Lid lag
  • Eye irritation
  • Exophthalmos
  • Ophthalmoplegia

Endocrine:

  • Neck fullness/tenderness (thyroid gland)

Cardiorespiratory:

GI:

Reproductive:

  • Oligomenorrhea
  • Gynecomastia
  • Telangiectasia

Gynecologic:

  • Menorrhagia
  • Sparse pubic hair

Hematologic:

  • Anemia
  • Leukocytosis

Dermatologic:

  • Hair loss
  • Pretibial myxedema
  • Warm, moist skin
  • Palmar erythema
  • Onycholysis

Apathetic hyperthyroidism: (elderly patients)[11]

  • Placid apaethetic facies
  • Depression
  • Lethargy
  • Muscular weakness and wasting
  • Excessive weight loss
  • Cardiac dysrrhythmias
  • Absent or small goiter
  • Absence of ocular symptoms
  • Agitation and confusion

Differential Diagnosis (Tachycardia)

Evaluation

Workup

  • TSH (↓)
  • Free T4 (↑)
  • Free T3 (↑)

Management

  • If asymptomatic or mild symptoms, no treatment required in ED
  • If symptomatic, consider Thyroid storm

Disposition

  • If asymptomatic or no thyroid storm, discharge with outpatient follow-up.
  • Admit for significant symptoms or thyroid storm.

See Also

References

  1. Thiessen, M. (2018). Thyroid and Adrenal Disorders. Rosen's emergency medicine: Concepts and clinical practice (9th ed.). Philadelphia, PA: Elsevier/Saunders
  2. Thiessen, M. (2018). Thyroid and Adrenal Disorders. Rosen's emergency medicine: Concepts and clinical practice (9th ed.). Philadelphia, PA: Elsevier/Saunders
  3. Thiessen, M. (2018). Thyroid and Adrenal Disorders. Rosen's emergency medicine: Concepts and clinical practice (9th ed.). Philadelphia, PA: Elsevier/Saunders
  4. Thiessen, M. (2018). Thyroid and Adrenal Disorders. Rosen's emergency medicine: Concepts and clinical practice (9th ed.). Philadelphia, PA: Elsevier/Saunders
  5. Thiessen, M. (2018). Thyroid and Adrenal Disorders. Rosen's emergency medicine: Concepts and clinical practice (9th ed.). Philadelphia, PA: Elsevier/Saunders
  6. Thiessen, M. (2018). Thyroid and Adrenal Disorders. Rosen's emergency medicine: Concepts and clinical practice (9th ed.). Philadelphia, PA: Elsevier/Saunders
  7. Thiessen, M. (2018). Thyroid and Adrenal Disorders. Rosen's emergency medicine: Concepts and clinical practice (9th ed.). Philadelphia, PA: Elsevier/Saunders
  8. Thiessen, M. (2018). Thyroid and Adrenal Disorders. Rosen's emergency medicine: Concepts and clinical practice (9th ed.). Philadelphia, PA: Elsevier/Saunders
  9. Thiessen, M. (2018). Thyroid and Adrenal Disorders. Rosen's emergency medicine: Concepts and clinical practice (9th ed.). Philadelphia, PA: Elsevier/Saunders
  10. Thiessen, M. (2018). Thyroid and Adrenal Disorders. Rosen's emergency medicine: Concepts and clinical practice (9th ed.). Philadelphia, PA: Elsevier/Saunders
  11. Rehman SU et al. Thyroid Disorders in Elderly Patients. South Med J. 2005;98(5):543-549.