“Cryptothyroidism,” the Major Cause of Sporadic “Athyreotic” Cretinism

Abstract

Seven patients with consecutively diagnosed “sporadic athyreotic cretinism” were scintiscanned after administration of 131I to determine whether or not any iodineaccumulating tissue was present and whether, if present, it was ectopic, as has been found in some patients by McGirr and Hutchison and others. In 6 of the 7 patients a small rest of radioactivity was found at a high ectopic site despite 24-hr thyroidal 131I uptakes of less than 10% in all patients. There was no evidence of this tissue on physical examination of the pharynx or tongue. Both the most severely affected patients and 2 with the onset after 1 yr of age showed such rests, although on scintiscans the frontal area of the active tissue was slightly larger in the latter. The relation of this finding to the pathogenesis of infantile and juvenile hypothyroidism and to endemic cretinism is discussed. By analogy with cryptorchidism, the term “cryptothyroidism” is suggested as an appropriate designation for this anomaly.