Misdiagnosis of thyroid disorders in down syndrome: time to re-examine the myth?

There is a reported association between thyroid disorders and Down syndrome, but is this association based on valid and reliable research evidence? We evaluated thyroid function test results of 110 healthy adults with Down syndrome to determine biochemical thyroid status. Approximately two thirds were biochemically euthyroid when assessed by standard reference ranges for the general population. We believe that there is a need for revalidation of "normal" thyroid function tests parameters when applied to the Down syndrome population and that persons with Down syndrome are possibly being misdiagnosed and inappropriately treated for a nonexistent medical disorder.