New Nationwide Data on Thyroid Storm: Rare but Deadly Emergency

Nancy A. Melville

January 11, 2019

Thyroid storm, though rare, occurs in approximately one of six patients hospitalized with a principal diagnosis of thyrotoxicosis, but the condition is associated with a mortality rate as much as 12-times higher than thyrotoxicosis without thyroid storm, according to new research.

"Providers caring for patients in urgent care, emergency rooms, and/or hospitals should be aware of the high morbidity and mortality of thyroid storm," first author Rodolfo J. Galindo, MD, an assistant professor of medicine and clinical researcher in the Division of Endocrinology at Emory University School of Medicine, in Atlanta, Georgia, told Medscape Medical News

"Collaborative efforts are needed to design standardized, evidence-based strategies — not just expert opinion recommendations — to diagnose and treat these patients," he stressed.

Thyroid storm, a severe form of thyrotoxicosis, is a potentially life-threatening thyrotoxic crisis; however, understanding of the rare condition, including incidence and mortality rates, is primarily based on single-center case series that are not very current.

The new study, published online in Thyroid, is the first nationwide analysis of hospitalized patients with thyroid storm in the United States. Galindo and colleagues conducted a longitudinal analysis using data from the National Inpatient Sample (NIS).

Galindo believes a patient registry is now needed to properly track cases of thyroid storm nationwide and inform future treatment recommendations. Meanwhile, physicians can use the Burch-Wartofsky Point Scale to help distinguish uncomplicated thyrotoxicosis from "impending" or established thyroid storm, he says.

And furthermore, "Clinicians, including emergency medicine specialists, hospitalists, and/or internists, should be adequately trained on the use of supportive care and thionamide drugs in patients with severe hyperthyroidism, and advised on consulting endocrinology specialists in a timely manner, since delaying treatment can lead to increased morbidity and mortality," he urged.

Around 15% of Severe Hyperthyroidism Cases Have Thyroid Storm

Thyroid storm is an acute, life-threatening, hypermetabolic state induced by excessive release of thyroid hormones in individuals with thyrotoxicosis. Thyroid storm may be the initial presentation of thyrotoxicosis in undiagnosed children, particularly in neonates, although the condition is rare in children.

Because thyroid storm is almost invariably fatal if left untreated, rapid diagnosis and aggressive treatment are critical. Diagnosis is primarily clinical, and no specific laboratory tests are available.

In the new study, among 121,384 hospital discharges with thyrotoxicosis identified between 2004 and 2013, 19,723 (16.2%) were diagnosed with thyroid storm, with overall incidence rates ranging between 0.57 and 0.76 cases per 100,000 people in the US per year, and between 4.8 and 5.6 per 100,000 hospitalized patients per year.

Hospital mortality rates were significantly higher in those with thyroid storm compared to those with thyrotoxicosis but without thyroid storm (1.2-3.6% vs 0.1-0.4%; P  < .01) and the average length of stay was also longer with thyroid storm (4.8-5.6 vs 2.7-3.4 mean days; P < .001).

The patient characteristics among those with thyrotoxicosis, regardless of whether they had thyroid storm or not, were similar, with the majority being middle aged and white, and about 76% were female.

There were no significant differences in mortality rates between ethnic groups; however, Hispanics and African Americans were more likely to be diagnosed with thyrotoxicosis complicated by thyroid storm compared with whites (20.8% vs 18.7% vs 13.7%, respectively; P < .0001).

Patients with thyroid storm were also more likely to have a history of Graves' disease (51.1% vs 41.4%; P < .001) and a history of noncompliance to medications (15.4% vs 5.9%; P < .001)

After multivariate adjustment, younger age and a Charlson Comorbidity Index score of less than 3 were associated with lower risk of mortality with thyroid storm (P < .05).

Costs, But Not Cases, On the Rise

Although the incidence of thyroid storm does not appear to be on the rise, costs associated with the condition have been progressively rising since 2007, with the mean hospitalization costs per admission, adjusted for inflation, increasing from $9942 to $12,661 in patients with thyrotoxicosis with thyroid storm from 2004 to 2013 (P < .001).

"From a policy perspective, these findings are remarkable, since the incidence, mortality, and length of stay trends of thyroid storm were stable over the study period," the authors write.

Factors that could have contributed to the increased cost could include those associated with the cardiovascular comorbidities of thyroid storm, they speculate.

In the study, those with thyroid storm had higher rates of associated cardiovascular conditions, including ventricular arrhythmias (2.5% vs 1.2%; P < .001), cardiac arrest episodes (1.3% vs 0.1%; P < .001), heart failure (19.4% vs 10.3%; P < .001), and acute coronary syndromes (1.8% vs 0.7%; P < .001).

Patients with thyroid storm also had higher rates of acute respiratory failure during hospitalization (5.9% vs 0.8%; P < .001) versus those without thyroid storm.

"It is suspected that the higher rate of acute severe cardiopulmonary conditions and the need for more invasive cardiac procedures and mechanical ventilation, which usually require admissions to coronary or intensive care units, may have impacted the increase in cost," the authors explain.

Call to Action for Thyroid Storm Patient Registry

Galindo noted that the hospital mortality rates of up to 3.6% for thyroid storm are lower than the approximately 8% to 10% in previous reports; however, the differences may reflect differing treatment settings.

"The present study represents data from academic and nonacademic, urban and rural hospitals throughout the United States, while previous reports were limited to tertiary academic centers where the acuity and mortality may be expected to be higher," he said.

Nevertheless, with such high morbidity and mortality rates, better documentation of thyroid storm is needed — beyond what can be offered in the NIS database, Galindo asserted.

"The database used [NIS] can provide us with valuable information to understand the clinical burden and the impact on the healthcare system of this condition in the United States. However, it was not developed as a research tool," he explained.

"Thus, we [propose] a call for action to create a prospective patient registry, including clinical, laboratory, and treatment data, to inform future evidence-based management recommendations for this condition."

Until then, Galindo reiterated that clinicians can use the Burch-Wartofsky Point Scale to help differentiate uncomplicated thyrotoxicosis from thyroid storm.

Galindo has reported no relevant financial relationships.

Thyroid. Published online December 18, 2018. Abstract

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