FALSE-POSITIVE REACTION FOR ACETONURIA

To the Editor:—  While testing, with phenolsulfonphthalein (PSP), the renal function of a patient with well-regulated diabetes mellitus, a strongly positive reaction for acetonuria was noted. This false-positive reaction was noted with the conventional test for acetone, using sodium nitroprusside, as well as with Acetest tablets (Ames Co.) and acetone test powder (Denco). These color reactions could be reproduced with PSP diluted with water and are undoubtedly due to the fact that all three tests for acetone take place at an alkaline p_H. The color produced by PSP is not exactly identical with that produced by acetone but is sufficiently similar to provide a source of error. The false-positive test result for acetone can readily be distinguished from true acetonuria by the failure of PSP to evaporate on boiling. The color could also be distinguished by spectroscopy, but this method of examination is not generally available. A positive ferric chloride