thyroid crisis the exacerbation of symptoms of hyperthyroidism; severe thyrotoxicosis; can follow shock or injury or thyroidectomy; marked by rapid pulse (140-170/minute), nausea, diarrhea, fever, loss of weight, extreme nervousness, and a sudden rise in the metabolic rate; coma and death may occur; occasionally the entire clinical picture is that of profound prostration, weakness, and collapse, without the phase of muscular overactivity and tachycardia. SYN: thyroid storm.