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UREA. 681
Thus Long and Gephart found in the urine of six healthy men to whom
the same qualitative diet was fed for a long time, the following division
of the nitrogen in percentage of the total nitrogen: urea 79.87-84.ill,
creatinine 5.21-6.87, ammonia 3.6-4.74, uric acid 1.57-1.99, purine
0.33-0.96 and rest nitrogen 4.23-6.01 per cent. Sjoqvist has made
similar determinations on new-born babes from 1 to 7 days old. From
all these analyses we obtain the following figures (A for adults and B for
new-born babes). Of the total nitrogen there exists:
A. B.
Per Cent. Per Cent.
Urea 84-91 73-76
Ammonia 2-5 7.8-9.6
Uric acid 1-3 3.0-8.5
Remaining nitrogenous substances 7-12 7.3-14.7
The variable relation between uric acid, ammonia, and urea nitro-
gen in children and adults is remarkable, since the urine of children
is considerably richer in uric acid and ammonia, and considerably poorer
in urea, than the urine of adults. A much larger number of analyses
of children’s urine is necessary to explain the division of the nitrogen
.therein. The absolute quantity of urea nitrogen in adults amounts to
about 10-16 grams per day. In disease the proportion of the nitroge-
nous substances may be markedly changed, and a decrease in the quan-
tity of urea and an increase in the quantity of ammonia have been observed
in certain diseases of the liver. This will be considered in detail in
connection with the formation of urea in the liver. It is natural that
there should be a diminished formation of urea after a decrease in the
ingestion of proteins or in a lowered catabolism. In diseases of the
kidneys which disturb or destroy the integrity of the epithelium of
the convoluted urinary tubules, the elimination of urea is considerabl}’’
diminished.
Recently by means of Pfaundler’s l
method, by precipitating the urine with
phosphotungstic acid and closely studying the precipitate as well as the filtrate,
it has been possible to learn further about the division of the nitrogen of the urine.
We determine a, the total nitrogen; b, the nitrogen of the phosphotungstate pre-
cipitate; and c, the nitrogen in the filtrate from the phosphotungstate pre-
cipitate. This last contains the urea, hippuric acid, o’xyproteie acids, and other
bodies whose nitrogen is ordinarily designated as monamino-acid nitrogen. The
urea nitrogen is especially determined. The bodies precipitated by phospho-
tungstic acid are not all known; but uric acid and purine basest ammonia,
creatinine, pigments, diamino-acids, diamines and ptomaines (if they occur), sul-
phocyanides, carbamic acid, urine mucoid, and proteid belong to this group.
Special methods have been suggested for the determination of several of these
substances (see below).
The urea nitrogen is always the greatest part of the total nitrogen,
but otherwise the division of the nitrogen undergoes considerable varia-
1
Zeitschr. f. physiol. Chem., 30.
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