The total nonprotein nitrogen of the blood has not been studied in children, so far as we are aware, and the urea of the blood has been determined only by the somewhat crude hypobromite method, to which, as Rowntree and Fitz1 have shown, an error of from 10 to 60 per cent. attaches. We have therefore thought it worth while to investigate the blood in this respect, in various diseases of childhood and in healthy children. We have also investigated the phenolsulphonephthalein excretion, using the method of Rowntree and Geraghty. Owing to the small material available, the series is far from complete.
The term "nonprotein nitrogen" is synonymous with incoagulable nitrogen, rest or waste nitrogen and retention nitrogen, and designates the nitrogen of those substances remaining after the removal of the proteins. It includes the urea, creatinin, amino-acids, uric acid, and ammonia of the blood.
—For the nonprotein
TILESTON W, COMFORT CW. THE TOTAL NONPROTEIN NITROGEN AND THE UREA OF THE BLOOD, AND THE PHENOLSULPHONEPHTHALEIN EXCRETION IN CHILDREN. Am J Dis Child. 1915;X(4):278-287. doi:10.1001/archpedi.1915.04110040051005