Thyroid radioiodine uptakes and scans in euthyroid patients

A substantial increase in the dietary iodide intake in many communities has caused a major increase in the total iodide pool in the body and a consequent decrease in the normal thyroid radioiodine uptake. Because of the pronounced regional variations in iodide supplementation of food, and because the effects of this additional dietary intake on radioiodine uptake are so large, a redefinition of the normal range of thyroid radioiodine uptake values in patients seen at this institution was thought to be indicated. The results of 6-hour and 24-hour thyroid radioiodine uptake studies in 44 euthyroid subjects, with scan data on the 20 who were studied with 123-I, are consistent with other reports indicating that the current normal thyroid radioiodine uptake values are lower than those accepted several years ago.