Frequently the physician reads of some new laboratory procedure that is not adapted for the average clinical laboratory and yet is of such practical significance to his daily work that it immediately becomes a part of his diagnostic armamentarium. Such is the case of the testing for aminoaciduria, the interpretation of which is reported on page 1571 of this issue of The Journal.
The losses of amino acids, per se, in the urine have not been shown to be of sufficient magnitude to produce amino acid deficiencies under ordinary dietary conditions. Aminoaciduria results from disturbances of the metabolism of amino acids. It can equally result from defects in the renal tubular reabsorption of the same amino acids; and, in regard to this latter phase, etiology would include many types of renal injury caused by inborn errors of cell metabolism, toxic agents, or vitamin deficiency states. In other words, studies revealing