A 3,3',5'-triiodothyronine (reverse T3) radioimmunoassay.

In this paper are reported the results obtained by a simple, reproducible and sensitive rT3 RIA, in unextracted serum, using the PEG separation technique. The linear correlation coefficient of the results obtained from extracted and unextracted sera, in a population of 60 adults and 35 child controls was 0.984, with a minimal spread of the data.