CORRELATION OF THE 24-HOUR RADIOIODINE UPTAKE OF THE HUMAN THYROID GLAND WITH THE SIX- AND EIGHT-HOUR UPTAKES AND THE “ACCUMULATION GRADIENT”

Abstract

The correlation of the accumulation gradient, 6-hour, and 8-hour uptake with the 24-hour uptake of radioactive I by the thyroid gland was investigated in euthyroid human subjects. A close correlation was found between all four functions. If y is taken to represent the 24-hour uptake and x the various other functions, relatively precise formulae can be constructed by means of which the 24-hour uptake can be calculated from any of the other functions and vice versa. Thus, y = 31.2x - 3.62x2 [plus or minus] 0.141y is the formula for the accumulation gradient, y = 1.67x[plus or minus] 0.129y is the formula for the 6-hour uptake, and y = 1.43x[plus or minus] 0.134y is the formula for the 8-hour uptake. These correlations hold even when the thyroid gland is suppressed by exogenous thyroid hormone. The data presented here may be of value in future investigations of thyroid physiology in euthyroid subjects. It is suggested that far less correlation would be expected in thyrotoxic subjects.