Usefulness of125I column triiodothyronine test, “Trilute”, measuring thyroid function indirectly by indicating the available thyroxine binding globulin sites was evaluated. Fundamental studies— Incubation time: This kit was considered to be convenient to determine many specimens at a time as there was no effect of incubation time on the results. Incubation temperature: Determination should be carried on at the room temperature of 25°C or higher, as the deviation by temperature correction is small at this temperature. A satisfactory reproducibiliy of the kit was obtained in measuring the sera from the subjects with various thyroid functions and from the pregnant women. Clinical studies— In normal subjects, the Trilute value ranged 38.14 to 65.70, without overlap with those of hyperthyroid and pregnant, but with considerable overlap with that of hypothyroid. A good correlation was observed between the values of Triosorb resin sponge uptake and that of Trilute. The values of Tetrasorb and Trilute were significantly correlated, with a exception of pregnant women, who showed higher value of Tetrasorb and lower value of Trilute. The Trilute test could be carried on simply and easily, with careful pipetting 0.05ml of serum specimen and with controlling the incubation temperature around 25°C, and was found to be useful routine examination of thyroid function.
Usefulness of Tetralute kit for measuring total serum thyroxine was evaluated. The characteristics and advantages of this method, compared with other in vitro thyroxine measurements were as follows. 1) Virtually all thyroxine is extracted from the serum by placing it in a strong alkaline Sephadex G-25 column. This procedure can be carried on easily in a short time. 2) Only 0.1 ml of serum specimen is used in this measurement. 3) Such an effect of the differences in incubation time or incubation temperature on the results as seen in methods using resin, was not observed. 4) As the most linear and accurate range of the standard curve was between 2.5 and 10.0μg thyroxine iodine per 100 ml, it was necessary to determine the specimens by increasing the amount of serum with lower concentration of thyroxine iodine than 2.5μg per 100 ml and by decreasing the amount of serum with higher concentration of thyroxine iodine than 10.0μg per 100 ml. 5) A satisfactory reproducibility of the kit was obtained in measuring the serum from the subjects with various thyroid functions and from the pregnant women. 6) The values of the thyroxine iodine concentration (μg/100 ml) ranged 5.53±1.30 in normal subjects, 15.40±3.77 in patients with hyperthyroidism, 1.64±1.21 in patients with hypothyroidism, and 8.07±1.87 in pregnant women. A good correlation between the value of Tetrasorb and that of Tetralute was observed. From these observations, it was concluded that the Tetralute test was useful screening technique for thyroid function with its simplicity and accuracy, although it was troublesome to change the volume of specimens with lower or higher concentration of thyroxine iodine than 2.5 or 10.0μg/100 ml.
Gel filtration with thin layer made of Sephadex was applied to the purity test of 3 kinds of radiopharmaceuticals containing iodinated (125Ior131I) high molecular substances. Sephadex G-50, Superfine was used to make thin layer for iodinated (125I) insulin solution and iodinated (131I) polyvinylpyrrolidone injection, and Sephadex G-200, Superfine was used for iodinated (125I) IgE solution, according to the molecular weights of these radiopharmaceuticals. Drops of these radiopharmaceuticals were spotted on wet thin layer plates and developed by declining technique with water for 1.5-5 hours. The distribution of radioactivities on these chromatograms was measured, and a sharp peak corresponding to the pure iodinated (125Ior131I) substance was observed in each case. So, this gel filtration procedure was regarded as a suitable method for purity test of these radiopharmaceuticals, detecting radioactivities due to possible degradation product and free iodine.