Hypothyroidism is a common disease among subjects with Down syndrome. Here, we provide a case report in which sudden behavioral changes in a patient with Down syndrome led to the detection of hypothyroidism in a preoperative examination. The patient was a 37-year-old woman with Down syndrome and intellectual disabilities. She required sedation or general anesthesia during dental treatment because of a noncooperative status. She had been given a prescription for a psychotropic drug because she had suddenly become agitated one month before the preoperative examination. However, she did not respond to the medication. Since we suspected underlying hypothyroidism, we performed a thyroid hormone test and discovered a significantly elevated TSH value of 170.9 μg/ml (normal range, 0.5-5.0 μg/ml), a low FT4 level of 0.36 ng/ml (normal range, 0.9-1.7 ng/ml), and a low FT3 level of 1.37 ng/ml (normal range, 2.3-4.0 ng/ml). Thus, she has been diagnosed as having hypothyroidism and was prescribed levothyroxine sodium. After six months, she achieved a euthyroid status. We then performed dental treatment under intravenous sedation with propofol and midazolam. No problems were detected during the overall perioperative process.
When behavior changes are recognized in patients with Down syndrome, the possibility of depression, the regression of social and communication skills, or Alzheimer disease should be considered. In addition, the possibility of physical problems, such as hypothyroidism, should also be taken into consideration. However, distinguishing these diseases based on clinical symptoms alone can be difficult because of overlapping symptoms. Consequently, the exclusion of hypothyroidism should be a top priority. Patients with Down syndrome who have not received periodic screening for hypothyroidism via blood tests should be given a thyroid function test prior to undergoing general anesthesia and sedation.
