ELEMENTARY CHEMICAL PHYSIOLOGY 273 



excretion of haemoglobin or methsemoglobin from the blood plasma 

 by the kidneys, called respectively hcemoglobinuria and methcemo- 

 globinuria. 



In any case the tests for haemoglobin can be applied. The guaiac 

 test, which is very sensitive, should be applied after boiling the 

 urine to destroy oxidases. The spectroscopic examination is also 

 very sensitive when an adequate depth of urine is employed (see 

 p. 245). 



Hsematuria is distinguished by the smoky appearance of the 

 urine and by examination of the urine, or deposit on centrifugalising, 

 when red blood corpuscles are seen. The spectroscope nearly 

 always shows the presence of oxyhsemoglobin. Blood from the 

 kidney is mixed with the urine. That from the bladder is often 

 present as a clot. If the red corpuscles have disintegrated, the 

 urine will present the appearance of hsemoglobinuria. If the urine 

 is stale, methsemoglobin may be present. 



In Hsemoglobinuria and Methsemoglobinuria red blood corpuscles 

 are not seen, and the urine is clear, not smoky. The two conditions 

 are distinguished by the colour of the urine and by the spectroscope. 



EXPERIMENT V. Test the urine supplied for blood and haemo- 

 globin. 



Bile in Urine. When the bile duct is blocked by a calculus, or 

 its mucous membrane is swollen from catarrh, the bile, which 

 accumulates in the bile channels, is reabsorbed into the blood- 

 vessels and carried to the tissues, which become stained with bile 

 pigment. Under these conditions the urine contains bile con- 

 stituents, the most easily recognised of which are the bile pigments. 



EXPERIMENT VI. Apply Gmelin's test (see p. 236) to the urine 

 of a jaundiced patient. Where only a small quantity of bile pig- 

 ment is present it is better to concentrate the pigment by proceeding 

 as follows : 



Add calcium chloride solution to the urine, and then sodium carbonate 

 solution, so as to form a precipitate of calcium carbonate and phosphate, 

 which carries down the pigment ; filter off the precipitate and dissolve it in 

 as small a volume of hot dilute hydrochloric acid as possible ; apply Gmelin's 

 test to this solution. 



Also apply Hay's sulphur test for bile salts (see p. 236). 



Sugars in the Urine. Although the presence of sugar in the 

 urine is normally associated with the disease known as diabetes 

 mellitus, it must not be forgotten that every case of glycosuria is 

 not of necessity a case of diabetes. The relation of the blood sugar 

 content (see p. 318) to the urinary condition is of prime importance. 

 Further, there are always traces of sugar to be found in perfectly 

 normal urine quite apart from the reduction which takes place 

 with Fehling's solution, for example, due to the presence of creatin- 

 ine, uric acid, urochrome, etc. 



The other sugars which the urine may contain are lactose and 

 pentose. The former of these is sometimes found in the urine of 



TJ 



