SPECIFIC GRAVITY OF URINE 379 



after the free use of alkaline medicines, or of the alkaline salts with carbonic 

 or vegetable acids; for these latter are changed into alkaline carbonates 

 previous to elimination by the kidneys. 



Specific Gravity of Urine. The average specific gravity of the human 

 urine is about 1020 to 1025. The relative quantity of water and of solid 

 constituents of which it is composed is materially influenced by the condition 

 and occupation of the body during the time at which it is secreted; by the 

 length cf time which has elapsed since the last meal; by the amount of water 

 taken; and by several other less important circumstances. The morning 

 urine is the best adapted for analysis in health, since it represents the simple 

 secretion unmixed with the elements of food or drink. If it is not used the 

 whole of the urine passed during a period of twenty-four hours should be 

 taken. The specific gravity of the urine may thus, consistently with health, 

 range widely on both sides of the usual average. It may vary from 1015 

 in the winter to 1025 in the summer; but variations of diet and exercise, 

 and many other circumstances, may make even greater differences than 

 these. The variations may be extreme in disease, sometimes decreasing 

 in albuminuria to 1004, and frequently increasing in diabetes, when the 

 urine is loaded with sugar, to 1050 or even to 1060. 



AVERAGE DAILY QUANTITY OF THE CHIEF URINARY CONSTITUENTS. (MODIFIED FROM 



PARKES.) 



Per Kilo of 

 Body Weight. 

 2 3. oooo grams 

 0.8800 

 .5000 

 .0140 

 .0084 

 .0060 

 .1510 

 .0480 



-0305 

 .1260 



Variations in the Constituents of Urine. Most of the constituents 

 are, even in health, liable to variations from the proportions given in the 

 above table. The variations of the quantity of water in different seasons, 

 and according to the quantity of drink and exercise, have just been men- 

 tioned. The water of the urine is also liable to be influenced by the condi- 

 tion of the nervous system, being sometimes greatly increased, e.g., in hysteria 

 and in some other nervous affections, and at other times diminished. The 

 increase in water may be either attended with an augmented quantity of 

 solid matter in some diseases, as in ordinary diabetes, or may be nearly the sole 



