PATHOGENESIS OF A CASE OF CONGENITAL GOITER WITH ABNORMALLY HIGH LEVELS OF SPI AND WITH MONO- AND DIIODOTYROSINE IN THE SERUM*

Abstract

RECENT studies have demonstrated the importance of enzymatic defects in the pathogenesis of congenital goiter (1–10). Such defects may be associated with the presence of abnormal constituents in the peripheral blood. Most recently, Stanbuiy and coworkers (7–10) observed 3 patients with congenital goiter and low levels of serum organic iodine, in whom mono- and diiodotyrosine constituted the bulk of the circulating organic iodine. They found a defect in dehalogenation of mono- and diiodotyrosine, both within the gland and peripherally. Two of the 3 patients were siblings, and 2 of these 3 were cretinous as well as goitrous. The present report concerns a patient with congenital goiter, also with mono- and diiodotyrosine in the blood, but with a seemingly different type of defect as the cause—namely possible failure of coupling of diiodotyrosine. The patient, a 5-year-old colored girl, had a goiter which was large and very vascular upon examination, a serum precipitable-iodine level of approximately 25 μg. per 100 ml., and mild hypothyroidism as estimated by body height and by the stage of epiphyseal maturation upon roentgen 4 examination (see Case Report in Appendix).Partition of the serum by paper chromatography after labelling with I¹³¹ revealed roughly equal activities of mono- and diiodotyrosine, triiodothyronine and thyroxine,¹ as well as inorganic iodide in somewhat larger amount. These results were confirmed by chemical analysis of the several fractions from the chromatogram. Despite the finding of iodotyrosines in the serum, dehalogenase activity in the gland and peripherally was observed to be approximately normal by the techniques used by Stanbury and collaborators.²