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Hyperthyroidism : Thyroid Storm


Case Synopsis

A 32-year-old woman undergoes emergent general anesthesia maintained with 1.2% isoflurane for fixation of a compound humeral fracture. Preoperative history is significant for anxiety and intolerance to heat. Physical examination is noteworthy for periorbital swelling; warm, moist skin with sweaty palms; and a noticeable midline lower neck mass consistent with an enlarged thyroid. Thirty minutes after induction, sinus tachycardia (128 beats per minute) with premature atrial contractions, arterial hypertension (195/100 mm Hg), and hyperpyrexia (core temperature 37.9° C despite a cool operating room environment) are noted. However, physical examination reveals the absence of muscle rigidity. The hemodynamic changes persist despite increasing the depth of anesthesia to 2% isoflurane supplemented with incremental doses of intravenous sufentanil.

Acknowledgment

The authors wish to thank Dr. Pam Roberts for her contribution to the previous edition of this chapter.

Problem Analysis

Definition

Normal regulation and activity of thyroid hormone are summarized in the chapter on hypothyroidism. Increased circulating thyroid hormones lead to a hypermetabolic state. The following definitions apply to clinical syndromes of hyperthyroidism:

  • True hyperthyroidism is thyroid gland hyperactivity with increased synthesis and secretion of thyroid hormone.

  • Thyrotoxicosis refers to the clinical and biochemical manifestations of excess thyroid hormone. It affects 2% of women and 0.2% of men in the general population. Causes include thyroid gland hyperactivity, ectopic thyroid hormone synthesis, and iatrogenic causes.

  • Thyrotoxic crisis or thyroid storm is a life-threatening complication of hyperthyroidism characterized by a severe, sudden exacerbation of thyrotoxicosis. Patients with uncontrolled hyperthyroidism presenting for surgical or trauma care are at considerable risk of developing thyrotoxicosis. Therefore it is critical that anesthesiologists carefully assess patients who may be at risk of thyroid storm before proceeding with anesthesia and surgery ( Table 11.1 ).

    TABLE 11.1
    Diagnostic Criteria for Thyroid Storm
    From Burch HB, Wartofsky L: Life-threatening thyrotoxicosis. Thyroid storm. Endocrinol Metab Clin North Am 22(2):263-277, 1993.
    Criteria Points Criteria Points
    Thermoregulatory Dysfunction Gastrointestinal-Hepatic Dysfunction
    Temperature (° F)

    • Manifestation

    • 99.0–99.9

    		5

    • Absent

    		0

    • 100.0–100.9

    		10

    • Moderate (diarrhea, abdominal pain, nausea/vomiting)

    		10

    • 101.0–101.9

    		15

    • Severe (jaundice)

    		20

    • 102.0–102.9

    		20

    • 103.0–103.9

    		25

    • ≥104.0

    		30
    Cardiovascular Central Nervous System Disturbance
    Tachycardia (beats per minute) Manifestation

    • 100–109

    		5

    • Absent

    		0

    • 110–119

    		10

    • Mild (agitation)

    		10

    • 120–129

    		15

    • Moderate (delirium, psychosis, extreme lethargy)

    		20

    • 130–139

    		20

    • Severe (seizure, coma)

    		30

    • ≥140

    		25
    Atrial fibrillation

    • Absent

    		0

    • Present

    		10
    Congestive heart failure Precipitant history

    • Absent

    		0 Status

    • Mild

    		5

    • Positive

    		0

    • Moderate

    		10

    • Negative

    		10

    • Severe

    		20
    Scores totaled
    >45 Thyroid storm
    25–44 Impending storm
    <25 Storm unlikely

  • Thyrotoxicosis factitia refers to thyrotoxicosis without true hyperthyroidism (e.g., intentional ingestion of synthetic thyroid hormone, ectopic thyroid hormone production) and is associated with decreased endogenous synthesis of thyroid hormone.

Recognition, Risk Assessment, and Implications

History

Patients with undiagnosed hyperthyroidism often have a history of anxiety (occasionally progressing to psychosis or even coma), significant recent weight loss, heat intolerance, gastrointestinal disturbances (diarrhea, nausea, vomiting, abdominal pain), unexplained fever, muscle weakness, and tremor. Presentation is different in younger and older patients. Younger patients present with classic adrenergic symptoms (e.g., tachycardia, restlessness, or tremor). Older patients present with apathetic symptoms, such as depression, fatigue, and weight loss, and may not have adrenergic signs or symptoms. Thyroid storm is usually precipitated by a stressful event such as surgery, childbirth, infection, myocardial infarction, diabetic ketoacidosis, or major trauma.

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