The early recognition of functional impairment of the kidney, which will sooner or later terminate in uremia, is one of the most important problems in the diagnosis and treatment of the various forms of renal disease. Recent progress in chemical analysis of the blood has been great, particularly with regard to the accumulation of nitrogen waste products as a sign of renal insufficiency. Yet often one will be disappointed in diagnosis and prognosis if too much stress is laid on the nonprotein nitrogen, the urea nitrogen, the uric acid or the creatinine readings of the blood.
For one may find excessive amounts of these substances in patients who die of myocardial insufficiency, and in whom, apart from passive congestion, the kidneys show no anatomic changes. If such patients recover, improvement of the function of the heart also quickly ameliorates the chemical condition of the blood. In cases of pneumonia or