Five cases of absence of iodide concentrating mechanism.

Five cases, 2 males and 3 females, with absence of iodide concentrating mechanism are reported. Three of the five subjects are siblings and the eldest sister has no symptom to account for the cretinism. All 5 cases have improved clinically following the administration of potassium iodide and 4 cases are still in a euthyroid state without any adverse effects during a half to more than 4 years. This study suggests that the absence of iodide concentrating mechanism might be erroneously diagnosed as athyroidal cretinism or adolescent non-toxic diffuse goitre, and may at times not show any clinical symptoms.