A 28-year-old woman, G1P0 at 24 weeks gestation, is evaluated in the surgical recovery uni… — USMLE Step 2 CK

A $28$ -year-old woman, G $1$ P $0$ at $24$ weeks gestation, is evaluated in the surgical recovery unit for sudden-onset agitation and severe palpitations. She underwent an uncomplicated subtotal thyroidectomy $18$ hours ago for medically refractory Graves disease. Her preoperative regimen included propylthiouracil and propranolol, but she admits to missing multiple doses in the two weeks preceding surgery due to severe nausea. Her temperature is $39.4^{\circ}\text{C}$ ( $102.9^{\circ}\text{F}$ ), pulse is $158/\text{min}$ and irregularly irregular, blood pressure is $165/70\text{ mm Hg}$ , and respirations are $24/\text{min}$ . Physical examination reveals marked diaphoresis, a fine resting tremor, and a clean, intact cervical incision without swelling or erythema. The lungs are clear to auscultation bilaterally, and the abdomen is soft and nontender. Fetal heart tracing is reassuring. ECG demonstrates atrial fibrillation with a rapid ventricular response. Which of the following is the most appropriate next step in the management of this patient?

A
Chest radiography and administration of incentive spirometry
B
Initiation of intravenous broad-spectrum antibiotics and blood cultures
Administration of intravenous propranolol, hydrocortisone, and propylthiouracilAnswer
D
Reassurance and continued observation for normal physiologic changes
E
Delay of therapy pending serum thyroid-stimulating hormone and free T4 levels

Answer

Administration of intravenous propranolol, hydrocortisone, and propylthiouracil

This patient is experiencing thyroid storm, a life-threatening thyrotoxic crisis typically triggered by a major stressor such as surgery, infection, or trauma. In this case, thyroid surgery in an inadequately prepared patient (due to nonadherence to preoperative antithyroid medications) precipitated the storm by causing a massive release of stored thyroid hormone into the bloodstream. The classic presentation includes hyperpyrexia, severe tachycardia (often complicated by atrial fibrillation), agitation, and profound diaphoresis. Thyroid storm is a clinical diagnosis and a medical emergency. Treatment must be initiated immediately with beta-blockers (e.g., propranolol) to control sympathetic overactivity, thionamides to block new hormone synthesis, and corticosteroids (e.g., hydrocortisone) to inhibit peripheral conversion of T

4

to T

3

and treat potential relative adrenal insufficiency. Although methimazole is typically preferred for hyperthyroidism in the second and third trimesters of pregnancy due to hepatotoxicity concerns with propylthiouracil (PTU), PTU remains the thionamide of choice in thyroid storm for ALL patients, including pregnant women. This is because PTU uniquely decreases peripheral T

4

to T

3

conversion in addition to halting new hormone synthesis.

Step-by-Step Solution

Analyze the postoperative vital signs and timeline.

The patient presents with extreme hyperpyrexia (

39.4^{\circ}\text{C}

), severe tachycardia with atrial fibrillation (

158/\text{min}

), diaphoresis, and marked agitation just

18

hours following a subtotal thyroidectomy.

To differentiate between normal postoperative recovery, early surgical complications, and systemic crises.

Synthesize the clinical findings with the patient's preoperative history.

The patient had poorly controlled Graves disease prior to surgery due to medication nonadherence. The physical manipulation of the thyroid gland during surgery caused a massive release of stored thyroid hormone, precipitating a thyrotoxic crisis (thyroid storm).

To establish the primary diagnosis driving the hemodynamic and neurologic instability.

Determine the most appropriate immediate medical intervention, accounting for the patient's pregnancy.

The patient requires immediate blockade of sympathetic hyperactivity, inhibition of new hormone synthesis, and cessation of peripheral T

4

to T

3

conversion. The correct regimen is a beta-blocker (propranolol), a thionamide (propylthiouracil), and a corticosteroid (hydrocortisone).

To halt the life-threatening physiologic effects of massive thyroid hormone release. Propylthiouracil is specifically chosen over methimazole here, despite the second-trimester pregnancy, due to its ability to block peripheral conversion.

Key Concept

Diagnosis and management of postoperative thyroid storm

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