[Standardized radioimmunologic determination of T 3]

A method for detection of total T3 in sera is described. Reagents, incubation conditions and two methods of separation of free from bound hormone (charcoal and PEG) have been accurately studied. Particular attention has been paid to the reagent preparation and to the stability of lyophilized products over time. The results obtained show that: 1) ANSA works better than Merthiolate as splitter of TBG-T3 binding. 2) Measurements performed changing incubation temperature gave results not significantly different. 3) The separation method does not affect results. The method is extremely rapid, 1 h of incubation at 37degreesC or 4 h at 4degreesC. The calibration curve is expressed as a ratio of the activity bound to a different concentration of hormone and is described by a linear function with a correlation coefficient higher than 0.995. Clinical results are in accordance with those reported by the literature.