UPTAKE OF I131-l-TRIIODOTHYRONINE IN VARIOUS ERYTHROCYTE ABNORMALITIES

Abstract

This study was undertaken to determine whether the erythrocyte uptake of I¹³¹-l-triiodothyronine is affected by various erythrocyte abnormalities and whether consistent variations occur in association with several abnormal hematologic conditions. Plasma protein-bound iodine levels were determined in most cases in an attempt to rule out unsuspected thyroid disease. Normal I¹³¹-l-triiodothyronine uptake Aalues ranged from 10.58 to 18.34 per cent. In 3 cases of sickle-cell trait, normal values were observed, whereas in 2 pregnant patients with the trait, uptake values were low. Normal uptakes were also recorded in 1 case of sickle-cell anemia, 1 of sickle-cell thalassemia and 3 of thalassemia trait. Varying results were obtained in 9 cases of hemolytic anemia; in 2 cases associated with acute leukemia the uptakes were elevated despite very low hematocrits; in 3 cases associated with Hodgkin's disease, normal uptakes were noted in 2 and an increased uptake in 1; values were normal in a case of congenital spherocytic hemolytic anemia and elevated in a case of congenital hemolytic anemia with unusual inclusion bodies. Uptakes were elevated in 6 of 8 cases of polycythemia vera, and the value was high-normal in the seventh. Although variations in hematocrit have been shown to affect erythrocyte uptake, this factor did not account for the elevations in this group. No correlation between erythrocyte uptake of I¹³¹-l-triiodothyronine and hematocrit could be made in the cases of polycythemia vera or in the cases of hemolytic anemia with elevated uptake values.