‘IODINE IN BLOOD AND THYROID VII. AN ANALYTICAL PROCEDURE FOR USE WITH SMALL SAMPLES: Pa&itai&CoL0OICAL RANGE OF CONCENTRATIONS

In studies of the metabolism of iodine, particularly in relation to endocrine function, it has become clear (1, 2, 3) that the function of the thyroid gland can be measured with considerable confidence by the newer methods of micro-analysis for iodine. Unfortunately, at the present time, the best methods avail.. able require 6 to 10 cc. of serum or plasma. This amount, although a great improvement on former methods, nevertheless limits seriously the use of iodine analysis. This is true because duplicate analyses are essential and it is difficult to obtain the requisite amounts of 25 to 40 cc. of whole blood repeatedly from ‘wen an adult patient; and also because the methods are useless for experimen-tation with small animals. In consequence, despite the demonstration (2) that the function of the thyroid can be measured satisfactorily by blood analysis, the method is not generally used either in the clinical or in the experimental laboratOry. In order to implement our present knowledge and make it available for general use it will be necessary to devise methods which employ amounts of serum o