MetroHealthAnesthesiaAnesthesia and Hyperthryoidism

Etiology
    Graves' disease
    toxic multinodular goiter
    thyroiditis
    TSH-secreting pituitary tumor
    functioning thyroid adenoma
    overdose of thyroid replacement hormone
Clinical Manifestations
  • weight loss
  • heat intolerance
  • muscle weakness
  • diarrhea
  • hyperactive reflexes
  • nervousness
  • Graves' disease: fine tremor, exophthalmos or goiter
  • tachycardia, atrial fibrillation, congestive heart failure
  • elevated serum total thyroxine, triiodothyronine and/or free thyroxine
Thyroid tests
  • T4
    • elevated in 90% of hyperthyoroid patients
    • low in 85% of hypothyroid patients
  • T3 elevation helps confirm hyperthyroidism
  • T3 falsely low (decreased peripheral conversion from T4) in
    • hepatic cirrhosis
    • uremia
    • malnutrition
  • TSH
    • elevation (plus low T4, T3) confirms primary hypothyroidism
    • low TSH and T4 indicates secondary hypothyroidism
  • thyroid scan shows normally functioning thyroid tissue
  • ultrasound differentiates cystic from solid masses
  • antibodies to thyroid components elevated in Hashimoto's thyroiditis
Medical Treatment
    Inhibit hormone synthesis (propylthiouracil, methimazole)
    Prevent hormone release (potassium, sodium iodine)
    Mask signs of adrenergic overactivity (propranolol)
    Destroy thyroid cell function (radioactive iodine)
Anesthetic Considerations

Preoperative
    Postpone elective surgery until patient euthyroid
    Normal thyroid function studies
    Resting heart rate < 85
    Continue antithyroid medications and beta-blockers through day of surgery
    Emergency case: control hyperdynamic circulation with esmolol infusion
Intraoperative
    Closely monitor
      Cardiovascular function
      Temperature
      Eyes (exophthalmos of Graves' disease)
    Thyroid surgery, consider:
      Elevation of head of bed 10-20 degrees
      Armoured endotracheal tube passed beyond goiter
    Avoid stimulation of sympathetic nervous system
    Thiopental good induction agent (antithyroid activity at high doses)
    Beware chronic hypovolemia -> induction hypotension
    Accelerated drug biotransformation
    No change in MAC
    Increased incidence of myopathies and myasthenia gravis
Postoperative



Send Comments to Greg Gordon MD, gjg@po.cwru.edu
Department of Anesthesiology
The MetroHealth System
2500 MetroHealth Drive
Cleveland, Ohio 44109-1998
Phone: (216) 778-4801
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