COMPARATIVE VALUES OF INDIGOCARMIN AND BLOOD BIOCHEMICAL TESTS: IN THE ESTIMATION OF KIDNEY FUNCTION

A comparison of the value of indigocarmin and the various blood biochemical tests with any idea as to which may be the most accurate or reliable in the determination of kidney function is probably, ona priorigrounds, doomed to failure. Indigocarmin is, as we all know, a dye employed to test the ability of the kidneys, in health or disease, to excrete an artificially introduced foreign substance—a so-called test of elimination. The blood biochemical tests, three of which we have elected to study in comparison, urea nitrogen, total nonprotein nitrogen, and creatinin, are determinations of the nitrogen content of the blood in one combination or another, which is held in the blood normally or in excess in the event of disease, especially of the kidneys, therefore, so-called tests of retention. Harrison1has found the provocative urea concentration most useful. He says that the "urea concentration factor" indicates that