Clinical application and mechanization of a simple and inexpensive method for estimating T 3 uptake in serum.

This very inexpensive method of estimating T(3) uptake, already described (Walther, 1971), uses only 0.1 ml of patient's serum and discriminates between thyrotoxicosis and myxoedema much better than the resin sponge method. It can readily be mechanized and the ;free thyroxine index' derived has normal limits of 3.0 to 8.0.