468 PHYSIOLOGICAL CHEMISTRY 



urine is an aid to prognosis and diagnosis of pulmonary tuberculosis. 

 Urochromogen is not present in normal urine. Its presence in patho- 

 logical urine is due probably to faulty oxidation, i.e., failure to oxi- 

 dize the chromogen to urochrome. Urochromogen may be detected by 

 oxidizing it to urochrome by means of potassium permanganate. In 

 this process a certain antecedent of Urochromogen is also oxidized 

 to urochrome. Whereas the diazo reaction (see page 469) is also 

 given by urines containing Urochromogen, it is claimed that the diazo 

 reaction does not show the presence of the precursor of Urochromogen. 

 Hence the Urochromogen reaction is said to be more constant and 

 uniform in its appearance. 



EXPERIMENT 



Urochromogen Reaction (Weisz). 1 Fill a test-tube a little less than one- 

 third full of urine, dilute it with 2 volumes of distilled water and mix thoroughly. 

 Pour one-half the diluted urine into another tube and to one of the tubes add 3 

 drops of a i per cent solution of potassium permanganate. Shake the tube 

 thoroughly. In the presence of urochromogen a yellow tint will appear in the 

 tube to which permanganate was added. 



The reaction is due to the oxidation of urochromogen to urochrome, 

 and is believed to be of value as an aid in prognosis and diagnosis of 

 pulmonary tuberculosis. The presence of sugar, albumin or urobilin 

 in low concentration does not interfere with the test. The test often 

 runs parallel with the diazo reaction (see below). The test is supposed 

 to be positive when the focus of the lung is so active or extensive as to 

 flood the blood with toxins or to break down the defensive forces of the 

 body. It is claimed, therefore, that this test will differentiate the 

 cases in which the tuberculosis is beyond help from the tuberculin 

 from those in which the body is liable to respond favorably to its 

 action. 2 Some investigators claim the test is not specific and that a 

 positive reaction will be obtained in many disorders other than 

 tuberculosis. 3 



1 Weisz: Munch, med. Woch., 58, 1348, 1911. 



Vitri: Semana Medica, 20, No. 28, 1913. 



Heflebower: Am. Jour. Med. Sci., 143, 221, 1912. 



Metzger and Watson: Jour. Am. Med. Ass'n, 62, 1886, 1914. 



Pignacca: Gazetta d. Osp. e delle Clin., 25, 353, 1914- 



Ferrannini: Riforma med., 31, 479, 1915. 

 8 M. and A. Weisz: Wien. klin. Woch., 25, 1183, 1912. 



Dozzi: Gazetta d. Osp. e delle Clin., 34, 815, 1914. 



Burgess: Jour. Am. Med. Ass'n, 66, 82, 1916. 

 3 Tuliato: Gazetta d. Osp. e delle Clin., 35, 1914. 



Martelli and Pizzetti: Policlinico, 21, April i, 1914. 



