Abstract
Hyperthyroidism is a common clinical problem associated with thyroid gland hyperactivity. Complications include thyrotoxicosis and thyroid storm. Radioiodine uptake can help distinguish the disorders associated with thyrotoxicosis. Multiple stresses can trigger thyrotoxicosis or thyroid storm in a patient with hyperthyroidism. Treatment consists of general supportive measures, control of autonomic dysfunction, blocking peripheral conversion of T 3 to T 4 , decreasing thyroid hormone production, and possibly removing thyroid hormone from the circulation.
Keywords
hyperthyroidism, thyrotoxicosis, 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:
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True hyperthyroidism is thyroid gland hyperactivity with increased synthesis and secretion of thyroid hormone.
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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.
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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
Criteria
Points
Criteria
Points
Thermoregulatory Dysfunction
Gastrointestinal-Hepatic Dysfunction
Temperature (° F)
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Manifestation
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99.0–99.9
5
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Absent
0
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100.0–100.9
10
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Moderate (diarrhea, abdominal pain, nausea/vomiting)
10
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101.0–101.9
15
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Severe (jaundice)
20
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102.0–102.9
20
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103.0–103.9
25
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≥104.0
30
Cardiovascular
Central Nervous System Disturbance
Tachycardia (beats per minute)
Manifestation
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100–109
5
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Absent
0
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110–119
10
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Mild (agitation)
10
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120–129
15
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Moderate (delirium, psychosis, extreme lethargy)
20
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130–139
20
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Severe (seizure, coma)
30
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≥140
25
Atrial fibrillation
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Absent
0
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Present
10
Congestive heart failure
Precipitant history
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Absent
0
Status
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Mild
5
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Positive
0
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Moderate
10
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Negative
10
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Severe
20
Scores totaled
>45
Thyroid storm
25–44
Impending storm
<25
Storm unlikely
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