Determination of thyroxine concentration in rat blood using radio immunological kits designed to determine the level of hormone in human blood

Abstract

The relationship between the matrix effect and radioimmunoassayed concentrations of total T₄ in the blood of rats was studied. T4 was measured 4 times in 59 rats: by the initial and modified RIO-T4-PG and RIA-T4-STkits (Minsk). The modification consisted in the following: standard solutions were prepared on rat serum free from T4. The levels of T4 measured by the original and modified kits correlated. For RIO-T4-PG the correlation coefficient p = 0.9809 and regression equation is у = 0.64x+5.087, and for RIA-T4-ST p = 0.9802 and у = 0.875x-l. 712. Hence, for real concentrations, measurements of T₄ by both original kits give underrated values, but the fluctuations of T4 in the control rats appreciably surpassed this underrating. We conclude that the above mentioned commercial kits for measuring T₄ can be usedfor measuring the hormone concentration in the rat blood, provided the appropriate reference groups are available.