In patients who are hyperthyroid, any condition that results in significant physiological stress can precipitate a thyroid storm; examples include infections, diabetic emergencies, pulmonary embolism, surgery, trauma, and childbirth. In addition, the untimely withdrawal of antithyroid medications can lead to rebound thyrotoxicosis; and the use of radioactive iodine can lead to a massive release of thyroid hormones from the thyroid follicles, precipitating thyroid storm.

A wide range of neuropsychiatric symptoms may occur. These include anxiety, hyperirritability, emotional lability, confusion, apathy, and coma. Rarely, dramatic psychotic symptoms, such as delusional parasitosis, can occur. The pathophysiology is complex; however, thyroid hormones are known to influence neurotransmitter release and hormone activation.

Gastrointestinal (GI) symptoms include jaundice, abdominal pain, and diarrhea. Jaundice is due to liver dysfunction; this may be due to acompanying autoimmune disease, or heart failure causing hepatic congestion and reduced blood flow. In patients who are purely hyperthyroid (i.e., without other complications), the pathophysiology of the liver dysfunction is unclear. Diarrrhea is due to increased motility, malabsorption, and increased adrenergic activity.