Table 2.

Summary of Nationwide Surveys in Japan

• Tentative diagnostic criteria, based mainly on patients in the literature, were initially developed for nationwide surveys of thyroid storm (TS).

• Nationwide surveys in the period from 2004 to 2008 were conducted in 2009 to obtain epidemiological data, including a five-year estimate of TS incidence in Japan, clinical features, and prognosis.

• The incidence rate is estimated to be 0.20 persons per 100,000 population per year in Japan, accounting for 0.22% of all thyrotoxic patients and 5.4% of hospitalized thyrotoxic patients.

• Graves' disease (GD) was the most common cause of thyrotoxicosis among patients with TS. In 45% of cases, the duration between TS onset and the initial diagnosis of GD was less than one year. Approximately 20% of patients developed TS before they received antithyroid drug (ATD) treatment.

• Factors classically considered to trigger TS were present in 70% of patients with TS. The most common trigger of TS was the irregular use or discontinuation of anti-thyroid medication. The second most common trigger was infection.

• The mortality rate of patients with definite or suspected TS was 10.7% (38/356). Individually, the mortality rates for definite and suspected cases were 11.0% and 9.5%, respectively.

• The most common causes of death in the 356 patients with TS were multiple organ failure (MOF) and congestive heart failure (CHF).

• Disease severities as assessed using Acute Physiology and Chronic Health Evaluation (APACHE) II and Sequential Organ Failure Assessment (SOFA) scores were significantly correlated with mortality.

• Glasgow Coma Scale (GCS) score and blood urea nitrogen (BUN) level were associated with irreversible damages in survivors.

• Serum thyroid hormone concentrations were similar among patients with TS patients but no TS. Several patients with TS had normal serum fT3 levels, increased serum fT4 levels, and suppressed serum TSH levels. FT3 and the fT3/fT4 ratio inversely correlated with disease severity.

• Compared with our initial diagnostic criteria, the only change in the final version of our diagnostic criteria for TS was the addition of serum bilirubin concentration >3 mg/dL.

• Most patients (78.1%) received methimazole (MMI). There were no significant differences in mortality or disease severity between patients treated with MMI and those receiving propylthiouracil (PTU).

• Mortality was significantly higher in patients treated with the non-selective beta-adrenergic receptor antagonists (beta-AAs) propanol than in patients treated with other types of beta-AAs.