EXCRETION 44g 



Inorganic Salts. The changes in the quantity of the in- 

 organic constituents of the urine in disease are not, in the present 

 state of our knowledge, of as much importance as the changes 

 in the organic constituents. The chlorides are diminished in 

 most acute febrile diseases and may even totally disappear 

 from the urine, and their reappearance after the crisis is, so 

 far as it goes, a favourable symptom. In most cases in which 

 the quantity of the urine is markedly lessened, all the inorganic 

 substances are diminished in amount. 



Urea. The quantity of urea is, as a rule, increased in fever, 

 either absolutely or in proportion to the amount of nitrogen in 

 the food. In the interstitial varieties of kidney disease the 

 urea is usually not diminished, but when the stress of the change 

 falls on the tubules (parenchymatous nephritis), it is distinctly 

 decreased it may be even to one-twentieth of the normal. 



Uric acid is diminished in the urine in gout (perhaps to one- 

 ninth of the normal), not only during the paroxysms, but in 

 the intervals. It accumulates in the blood and tissues, and, as 

 sodium urate, may form concretions in the joints, the cartilage 

 of the ear, and other situations. Watson relates the case of a 

 gentleman who used to avail himself of his resources in this 

 respect by scoring the points at cards on the table with his 

 chalky knuckles. In leukaemia the quantity of uric acid and purin 

 bases in the urine is greatly increased, not only absolutely, but 

 also in proportion to the urea. As much as 4^ grammes of free 

 uric acid, in addition to about ij grammes of ammonium urate, 

 has been found in a urinary sediment in a case of leukaemia. 



The aromatic bodies, of which indoxyl may be taken as the 

 type, are increased when the conditions of disease favour the 

 growth of bacteria in the intestine e.g., in cholera, acute peri- 

 tonitis, and carcinoma of the stomach. A marked increase in the 

 amount of the ' indican ' in the urine may, as far as it goes, be 

 taken as an indication that the bacteria are gaining the upper 

 hand in the intestinal tract ; a marked diminution is usually a 

 sign that the battle has begun to turn in favour of the organism 

 (Practical Exercises, p. 479). Tryptophane, a substance which 

 we have already recognised among the products of the tryptic 

 digestion of proteins, has been shown to be a precursor of indol, 

 which is formed from it under the influence of bacteria. When 

 tryptophane is injected into the caecum of rabbits, the indican in 

 the urine is markedly increased. Putrefactive processes in 

 other parts of the body than the intestine may also increase the 

 indican in the urine e.g., a collection of putrid pus in the pleural 

 cavity. 



Abnormal Substances in Urine. Sugar, proteins, the pig- 

 ments of bile and blood, or their derivatives, are the most 



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