EXCRETION BY THE KIDNEYS 4 i'i 



best, and to whom no blame whatever attached, carried the kidney to 

 a well-known pathologist for examination. The latter, to the horror 

 of the operator, suggested, from the appearance of the organ, that it 

 was the only kidney the woman possessed. This turned out to be the 

 fact. Not a drop of urine was passed. Apart from this ominous 

 symptom, all went well for seven or eight days; but then uraemic 

 troubles came on, and the patient died on the eleventh or thirteenth 

 day after the operation. The necropsy showed that her only kidney 

 had been taken away. 



In disease the urine may contain abnormal constituents, or ordinary 

 constituents in abnormal amounts. Of the normal constituents which 

 may be altered in quantity, the most important are the water, the inor- 

 ganic salts, the urea, the uric acid, and the aromatic substances. 



Water. A marked and persistent diminution in the quantity of 

 urine that is to say, practically in the water, with or without an 

 increase in the specific gravity is suggestive of disorganization of the 

 renal epithelium. In some infective diseases the kidney is liable to 

 be secondarily involved, its secreting cells being perhaps crippled in the 

 attempt to eliminate the bacterial poisons. In the form of paren- 

 chymatous or tubal nephritis which so frequently complicates scarlet 

 fever, the quantity of urine has in some cases fallen to 50 or 60 c.c. in 

 the twenty-four hours. 



In chronic interstitial nephritis (' granular kidney '), on the other 

 hand, where the structural changes in the tubules are, for a long time 

 at least, comparatively circumscribed, the quantity of urine is often 

 increased and of low specific gravity. In chese cases the increase in 

 the blood-pressure, associated with hypertrophy of the heart, may be 

 a factor in the exaggerated renal secretion. In diabetes mellitus the 

 quantity of urine is greatly increased, perhaps in some cases because 

 more urea is excreted than normal, and urea acts as a diuretic, perhaps 

 also because the elimination of sugar draws with it an increased excretion 

 of water to hold it in solution. Although a specific gravity as low as 

 1002 has been seen in healthy persons (after copious potations), the 

 persistence of a density below 1010 should suggest hydruria. Watson 

 mentions the case of a boy with diabetes insipidus, who voided in 

 twenty -four hours 9 or 10 pints (5 to 6 litres) of urine with a specific 

 gravity of 1002. On the other hand, while the specific gravity has been 

 occasionally observed to mount in health to at least 1036, its persistence 

 at 1025 or 1030 or anything above this, especially if the urine is pale 

 and apparently dilute, should suggest diabetes mellitus. 



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

 stituents of the urine in disease are not, in the present state of our 

 knowledge, of as much importance as the changes in the organic con- 

 stituents. 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 



