1972 Volume 21 Issue 8 Pages 487-491
A Res-O-Mat ETR test is used for an in vitro measurement of free thyroxine index which has been otherwise determined by calculation from the results of T3-test and T4-test.
Res-O-Mat ETR tests were measured in 120 sera from the euthyroid patients, patients with thyroid dysfunction or with TBG abnormality.
The reproducibility test with the same sera was satisfactory.
Res-O-Mat ETR test showed almost the same accuracy as T4-test or T3-test did in serum from the patient without TBG abnormality. In the sera with TBG abnormality, this test represents the thyroid function more accurately than T4-test or T3-test.
Results of this test and free thyroxine index calculated from the results of T4-test and T3-test, show a good linear correlation.