Thyrotoxic storm

Although a rare presentation of the exaggerated manifestations of thyrotoxicosis, thyrotoxic storm is arguably the most serious complication of hyperthyroidism because of its high mortality rate. An accurate estimation of its incidence is impossible to determine because of considerable variability in the criteria for its diagnosis. The syndrome does appear to be significantly less common today than in the past, perhaps because of earlier diagnosis and treatment of thyrotoxicosis, thereby precluding its progression to the stage of crisis. Nevertheless, the syndrome may occur in 1–2% of hospital admissions for thyrotoxicosis. In such patients, it is not usually possible to distinguish those with thyrotoxic storm from those with uncomplicated thyrotoxicosis simply on the basis of routine function tests. Rather, the clinical diagnosis is based on the identification of signs and symptoms which are seen typically in thyrotoxic storm and which suggest decompensation of a number of organ systems. Some of these typical or cardinal manifestations include fever (temperature usually above 38.5°C), tachycardia out of proportion to the fever, central nervous system signs varying from confusion to apathy and even coma, and gastrointestinal dysfunction, which can include nausea, vomiting, diarrhoea, and, in severe cases, jaundice. A semiquantitative scale (Table 3.3.3.1) has been developed to aid in diagnosis (1). The earliest possible diagnosis and subsequent implementation of treatment are required to avoid a fatal outcome. Even with early diagnosis, death can occur, and reported mortality rates have ranged from 10% to 75% in hospitalized patients (1–3).