URINE AND ITS CONSTITUENTS. 705 



Urochrome is the yellowish pigment of urine ; the quantity excreted, 

 as far as known, has no clinical significance. It is probably a deriva- 

 tive of bilirubin. 



Uroerythrin is a red pigment, and causes the pink color often seen 

 in urinary sediments. It occurs in very minute quantity in normal 

 urine, and is increased by muscular activity, profuse sweating, ex- 

 cessive eating, alcohol excess, digestive disturbance, circulatory dis- 

 turbance of the liver, malaria, pneumonia, and many other patho- 

 logical conditions. Whenever present in sufficient quantity to give 

 a rose color to the sediment or to the precipitate produced by adding 

 barium chloride to the urine, uroerythrin is excreted in increased 

 quantity. 



Urobilin y a reddish-brown pigment, occurs normally in very small 

 quantity, but it increases considerably whenever there is great de- 

 struction of haemoglobin in the body (internal hemorrhage, pernicious 

 anemia, poisoning by antipyrine), in cirrhosis of the liver, and dur- 

 ing high fever. When present in excessive quantity urobilin colors 

 the urine a dark brownish-red, and the foam shows a yellow or yel- 

 lowish-brown color. 



It is thought to be usually present in the condition of a chromogen, 

 called urobilinogen, producing the pigment urobilin after being acted 

 upon by light or by an acid. 



The presence of urobilin can be demonstrated by the spectroscopic exam- 

 ination of urine to which a small amount of hydrochloric acid has been added. 

 It may be necessary to let this mixture stand a short time, or to dilute it, or to 

 examine the amyl alcohol extract. The characteristic spectrum shows a 

 single band between B. and F. Urine containing urobilin will give a green 

 fluorescence on the addition of 1 per cent, zinc chloride, if it has been previ- 

 ously made alkaline with ammonia and filtered. 



Abnormal coloring-matters are chiefly those of blood, bile, and of 

 certain vegetables and drugs. 



Blood-pigment is usually present alone as methaemoglobin in hgemo- 

 globinuria, and associated with the red blood-corpuscles in haematuria. 

 Bile-pigment will be discussed later. 



The ingestion of rhubarb, senna, or santonin produces a bright 

 yellow color in the urine which becomes red on the addition of an 

 alkali. Methylene-blue is excreted by the kidneys and colors the 

 urine blue. Urines which become very dark on standing occur after 

 the ingestion of phenol, in cases of melanotic sarcoma (melanogen), 

 and in alkaptonuria, an unexplained pathological condition in which 



45 



