BETA - OXYBUTYRIC ACID - DIABETES.
A formal test for oxybutyric acid need be made only when certain provisional tests have furnished a presumption of the presence of this substance. The presence of the acid is rendered probable : 1. When Fehling's titrate method gives evidence of the presence of considerably larger amounts of sugar than does the polarization test. Grape sugar rotates the plane of polarization to the right, oxy butyric acid to the left; when, therefore, oxybutyric acid is present in considerable a part of the dextrorotatory power of the grape sugar is nullified, or it may even be that there is so much oxybutyric acid that the plane of polarization is actually rotated to the left.
2. When the urine, after complete fermentation with yeast, is found to be levorotatory.
3. When the urine, after ,precipitation with basic acetate of lead and ammonia, is levorotatory. By means of these reagents the sugar is practically entirely removed, but the oxybutyrate of lead remains in solution and passes through with the filtrate.
The application of these methods, when it gives a positive result, renders the presence of oxybutyric acid very probable. But we must be sure that the patient has not taken large amounts of benzosol, for this substance also rotates the plane of polarization to the left. The presence of levulose (after the consumption of a large amount of fruit sugar) does not invalidate this presumption, if the fermentation or lead-and-ammonia tests have been employed.
In order to determine with absolute certainty the presence of oxy butyric acid and to estimate its quantity we must resort to the method of Minkowski (as described in the paper of H. Volpe in the Archiv Jhr experbnentelle Pathologic uncl Phannahologie, Bd. XXI., S. 140, 1886) or to that of Kiilz (Zeitschrift Biologie, Bd. XXIII., S. 321, 1887).