URINALYSIS
The importance of the kidney functions has been clearly demonstrated.
Urine, which is the fluid secreted by these organs, is one of the most
important sources of information, not only as to the manner in which
the body utilizes food in health, but as an index to certain
pathological conditions, the processes of which are more or less
indicated by the products excreted in the urine.
~Function of the Kidneys.~--The kidneys, as has already been stated,
furnish a means by which the greater part of the waste products of the
body are eliminated and in addition to this function they adjust the
salts in the body. In an early chapter the function of the salts in
food was explained. A certain amount of these substances, we know, is
absolutely necessary to carry on the work in the body, but harm comes
when a surplus is retained in excess of that which can be used in
performing the various processes. Consequently the function of the
kidneys to adjust the salts balance is by no means their least
important one.
~Elimination of the Toxins.~--The toxic substances manufactured in the
body and those resulting from bacterial action upon unabsorbed
proteins are likewise eliminated in the urine. Thus it can be readily
understood how necessary it is to keep these organs in good repair,
that they may continue their work in an efficient manner.
It is necessary from a pathological standpoint for the nurse to
understand the making of some of the simpler tests, that she may
simplify her own work and that of the physician.
~Excretion of Carbon Dioxide and Water.~--We have already spoken of
the combinations of carbon and hydrogen compounds. These substances
being oxidized, the carbon dioxide produced is eliminated by way of
the lungs and the water is excreted partly by way of the lungs and
skin, but chiefly by way of the kidneys.
~Oxidation and Excretion of Nitrogenous Substances.~--When the
nitrogenous substances are oxidized, the used-up oxygen products are
eliminated by the kidneys in the form of urea and more or less highly
oxidized substances, such as ammonia and other salts, purin bases, and
creatinin.
~Uric Acid~, the chief of the oxidation products of nucleoproteins, is
produced in the body and from food, and is always in the urine, being
one of its normal constituents. It is only when this substance is in
excess in the urine that a pathological condition is indicated.
~Examination of the Urine~, then, is made for several different
purposes: (1) to ascertain whether the kidneys are doing their work
properly; (2) to find if the kidneys, or any part of the urinary
tract, are either temporarily or permanently diseased; (3) to be able
to judge from the various substances in the urine whether there is any
abnormal process taking place in the body.
~Tests.~--In the examination of the urine for the above purposes,
certain definite tests are made. These tests differentiate between the
abnormal and the normal.
(1) Color.
(2) Amount in twenty-four hours.
(3) Odor.
(4) Specific gravity.
(5) Reaction, acid or alkaline.
(6) Albumen, indican, acetone bodies.
(7) Sugar.
(8) Microscopic examination for casts, cells, bacteria, etc.
~The Color~ of normal urine varies, especially with the amount voided.
The variations in color range from the pale straw color of individuals
who are voiding large quantities to the deep lemon or amber of those
who void much less.
Pathological conditions are indicated to a certain extent by the color
of the urine. Fevers heighten the color, small quantities of blood
cause a smoky appearance, while bile changes the color of the urine to
a greenish yellow.
~Precipitates in the Urine.~--When the urine has been allowed to stand
for a time there is sometimes a brick-red deposit due to the
precipitate of urates. This disappears upon heating and is not an
evidence of any diseased condition.
~Turbidity of Urine.~--The turbidity of fresh urine then is the only
kind which need be considered, since standing in the cold often brings
about this condition, due to the growth of bacteria and deposits of
both phosphates and urates.
~Requirements in Testing Urine.~--Urine to be tested should be fresh,
and when it is not possible to make the examination at once it should
be preserved with chloroform, or some other harmless preservative,
until ready to use.
~Bacteria in Urine.~--The changes due to bacterial growth in the urine
are manifested not only by the turbid character of the urine but also
by the odor of ammonia.
~The Amount of Urine.~--The amount of urine voided in twenty-four
hours varies with the individual in health as well as in disease. Many
individuals void a great quantity during the twenty-four hours,
chiefly because they drink a great quantity of water and other
beverages. The average amount of urine passed in twenty-four hours by
an adult, or a child over eight years, is from 1000 to 2000 c.c. It
represents from 60% to 70% of the amount of water ingested.
~Collecting the Urine for Testing.~--In measuring the urine it is
necessary to begin collecting it after the bladder has been emptied
the first thing in the morning. The patient should void just before
the end of the twenty-four-hour period to be sure that the amount
formed by the kidneys during this time is accounted for.
~Diseases in Which Urine Is Diminished.~--In certain diseases the
amount of urine passed is diminished. This is found to be true in
diarrhea and dysentery, when water is lost in the feces, in hemorrhage
from any part of the body and from vomiting. It is likewise at times
the case after abdominal operations and in nervous conditions, such as
hysteria. The urine is diminished when there is an organic obstruction
in the urinary tract and certain obstructive diseases of the heart,
the lungs and the liver. In these latter cases, there is seen to be a
retention or suppression of urine. In both acute and chronic nephritis
and in certain fevers, the bladder at times must be emptied by means
of a catheter. At other times, the condition is relieved as far as
possible by limiting certain articles of food in the diet. At any
rate, these points must be kept in mind when examining the urine.
~Effect of Food upon the Urine.~--The odor of normal urine is changed
after eating certain foods, such as onions and asparagus. In disease,
the odor of urine has a distinct value as a means of diagnosis;
cystitis gives a foul odor, certain bacteria bringing about a
decomposition in the urine and giving rise to an odor of putrefaction.
In cases where there is a fistula connecting the bladder and rectum,
the urine has a fecal odor.
~Specific Gravity of Normal Urine.~--The density or specific gravity
of urine means the weight of any volume of urine as compared with
that of equal volume of distilled water. The specific gravity of
normal urine varies from 1012 to 1024, that is, in a thousand cubic
centimeters of urine there are found from 11 to 18 grams of solid
material. In health it is necessary to know the amount of urine passed
in twenty-four hours, to be able to judge whether the amount of solids
is too high or too low.
~Specific Gravity of Diabetic Urine.~--In conditions like diabetes
mellitus, where there is a wastage of sugar taking place in the
body--that is, instead of being oxidized to carbon dioxide and water
and glucose, the sugar is passing into the urine without completing
its oxidation--the specific gravity rises in these cases to 1030 and
over, showing distinctly that a greater amount of solid material is in
the urine than is present normally. In chronic Bright's disease and
diabetes insipidus, the specific gravity is low.
~Method of Determining Specific Gravity.~--The specific gravity is
determined by the use of an instrument known as a urinometer. The
urine is poured into a tube and the urinometer is dropped into it. The
different figures are marked upon the stem of the instrument and it is
a simple matter to read off the figures of the level to which the stem
sinks.
~Reaction to Litmus.~--In a former chapter it was stated that normal
urine was, as a rule, acid, that is, it turns blue litmus red. Certain
diseases render the urine alkaline. A like result is brought about
upon the ingestion of sodium citrate or bicarbonate of soda. Urine
which stands and becomes decomposed is alkaline in reaction, due to
the bacterial action, with the production of ammonia.
~Albumen in the Urine.~--The presence of albumen in the urine is
important, since normal urine does not contain this material in
quantities sufficient to be recognized by ordinary tests. Hence in
disease its presence is an indication of pathological processes taking
place either in the kidney or the urinary passages. The chief
abnormal condition indicated by the presence of albumen in the urine
is nephritis. Traces of albumen may occur in patients with fever or a
heart weakness. Blood and pus in the urine likewise indicate albumen.
When the nephritic condition is chronic, the kidneys themselves are
diseased and the presence of albumen may be in traces only, while
during the acute attack large quantities may be passed, but the urine
will clear up after a time.
~Benedict's Qualitative Sugar Test.~--Boil 5 c.c. of Benedict's
solution; add 8 drops of urine to be examined; hold the tube over the
flame and allow to boil vigorously for 3 minutes and set aside to cool
of itself. In the presence of sugar the entire solution will be filled
with a precipitate which may be greenish, yellow, or red, according to
the amount of sugar present. When the percentage of sugar is low
(under 0.3%) the precipitate will form only upon the cooling of the
solution. If there is no sugar present, the solution will either
remain clear or show a slight turbidity, due to the precipitation of
urates. The nurse must remember that to be useful the test must be
made accurately. There must never be more than 10 drops of urine and 8
drops is the usual quantity. The boiling must be vigorous and the
solution allowed to cool spontaneously.
~Fehling's Test for Sugar.~--Fehling's alkaline solution and Fehling's
copper solution must be kept in separate bottles until ready for use.
Then about 2 c.c. of Fehling's alkaline solution is poured into a test
tube and 2 c.c. of Fehling's copper solution is added. This is diluted
with hydrant water to 8 c.c. Half of this quantity is sufficient for
the test. The upper half of the solution is boiled over flame (gently
agitated while heating), and while still boiling a few drops of urine
are added. If no change appears, it is boiled again and a few drops
more of urine are added. If a reddish precipitate appears, sugar is
present. The chemical reaction taking place is the reduction of copper
sulphate to cuprous oxide. Sometimes a partial reduction occurs when
urates are in excess, but once having seen the real reduction, a
partial one cannot mislead the examiner.
~Haines's Test.~--Pour 1 teaspoonful of Haines's solution into a test
tube and boil gently over a Bunsen burner; add 6 or 8 drops of urine
and again heat to boiling. A yellow or red precipitate will indicate
the presence of glucose.
QUANTITATIVE TEST FOR SUGAR
~Benedict's Test.~[110]--The simple quantitative test for sugar is the
one devised by Benedict. This is simpler than the polariscopic
examination and better suited for ordinary use.
Place 5 c.c. of Benedict's quantitative solution in a small dish, add
a little less than one-fourth of a teaspoonful of sodium carbonate and
one-eighth of a teaspoonful of talcum and add 10 c.c. of water. Dilute
urine (1 part urine to 9 parts water) except where the qualitative
test showed a low percentage of sugar, that is, when the precipitate
turns green instead of yellow, in which case it will be unnecessary to
dilute the urine. Place dish over burner and bring the contents to a
boil. Pour the urine into a graduated pipette. Now add the urine drop
by drop to the contents in the dish until the blue color entirely
disappears. This test should be done over several times to assure an
accurate calculation. The calculation is made as follows: 5 c.c. of
Benedict's quantitative copper solution are reduced by 0.01 gram of
glucose, consequently the quantity of undiluted urine required to
reduce 5 c.c. Benedict's solution contains 0.01 gram of glucose.
0.01
------ x 100 = per cent. _x_ = c.c. of undiluted urine.
_x_
Example; 1500 c.c. urine in 24 hours. 5 c.c. used to reduce
(decolorized) Benedict's solution.
0.01
------ x 100 = 0.2 per cent.
5
1500 x 0.002 (0.2 per cent.) = 3 grams of sugar in 24 hours.
Example: If the urine had been diluted with 9 parts water, in other
words, 10 times, the calculation would be 5 c.c. diluted urine = 0.5
c.c. actual urine.
0.01
------ x 100 = 2 per cent.
0.5
1500 x 0.02 (2 per cent.) = 30 grams of sugar in 24 hours.
Hill and Eckman perform the Benedict's quantitative test as
follows:[111]
Measure with a pipette 25 c.c. Benedict's solution into a porcelain
dish, add 5 or 10 grams approximately of solid sodic carbonate, heat
to boiling, and while boiling, run in urine until a white precipitate
forms, then add urine more slowly until the last trace of blue
disappears. The urine should be diluted so that not less than 10 c.c.
will be required to amount of sugar which 25 c.c. of reagent is
capable of oxidizing.
Calculation: 5 divided by number of cubic centimeters of urine run in
equals per cent. of sugar.
~Fermentation Test for Quantity of Sugar in Urine.~--If the urine is
70 deg. F. (room) temperature when the specific gravity is taken at both
the beginning and end of the test, it will assure accuracy.
To 100 c.c. of urine of known specific gravity, add one-fourth of
fresh yeast cake thoroughly broken up. Mix thoroughly and set aside at
a temperature between 85 deg. and 95 deg. F. for twenty-four hours, after
which time test with Benedict's or Fehling's solutions. If reduction
is obtained, it will be necessary to allow the fermentation to
continue until it is complete. When no further reduction is obtained,
the specific gravity is taken after the urine has reached a
temperature of 76 deg.. The difference in the specific gravity at the
beginning and end of the test multiplied by 0.23 gives the percentage
of sugar in the urine.
The following formulas represent the various solutions used in the
above test:
BENEDICT'S QUALITATIVE SOLUTION
_Gm. or c.c._
Copper sulphate (pure crystals) 17.3
Sodium or potassium citrate 173.0
Sodium carbonate (anhydrous) 100.0
Distilled water to make 1000.0
FEHLING'S SOLUTION
(1) Copper Sulphate Solution:
34.65 grams copper sulphate dissolved in water and sufficient
water added to make 500 c.c.
(2) Alkaline Solution:
125 grams potassium hydroxide.
173 grams Rochelle salts dissolved in water q.s. to make 500 c.c.
Keep solution in separate bottles and mix in equal quantities when
ready to use.
HAINES'S SOLUTION
Copper sulphate (pure) 30 grams
(dissolved in 1/2 oz. (15 c.c.) distilled water)
Add 1/2 oz. pure glycerin, mix thoroughly, and add 5 oz. liquor
potassae.
BENEDICT'S (QUANTITATIVE) SOLUTION
Copper sulphate (pure crystals) 18 grams
Sodium carbonate (crystallized) (or 100 grams
of anhydrous salt) 200 grams
Sodium or potassium citrate 200 grams
Potassium sulphocyanide 125 grams
5% solution of potassium ferrocyanide 5 c.c.
Distilled water to make total volume of 1000 c.c.
Dissolve the carbonate, citrate, and sulphocyanide with the aid of
heat and enough water to make 800 c.c. of mixture. (Filter, if
necessary.) Weigh exactly the copper sulphate crystals and dissolve in
100 c.c. of water, now add it to the first solution; stirring
constantly. Add the ferrocyanide solution; cool and dilute to exactly
1 liter.
50 mg. (0.050 gm.) of sugar will reduce 25 c.c. of the above solution.
~Gerhardt's Ferric Chloride Reaction for Diacetic Acid.~--To 10 c.c.
of fresh urine, add carefully a few drops at a time of undiluted
aqueous solution of ferric chloride U.S.P. A precipitate of ferric
phosphates first forms, but upon the addition of a few more drops of
the same solution it is dissolved. A Burgundy red (red wine) color is
obtained in the presence of diacetic acid. The depth of this color is
indicative of the quantity of acid present. Joslin[112] records the
intensity of the reaction as follows, +, ++, +++, or ++++.
According to Joslin, it must be remembered that similar reaction is
obtained in the urine of individuals taking salicylates, antipyrin,
cyanates, or acetates, but it is a simple process to differentiate
between the color produced as a result of diacetic acid and that
produced by the above-mentioned drugs. If the solution is boiled for
two minutes, the color from diacetic acid will disappear, owing to the
unstableness of that substance, while that from the drugs will remain
unchanged.
~Test for Acetone.~--Pour 5 c.c. of urine to be tested into a test
tube, add a crystal of sodium nitroprusside, acidify with glacial
acetic acid, shake well, and then make alkaline with ammonium hydrate.
The presence of acetone is indicated by a purple color.
TESTS FOR ALBUMEN
The heat test[113] is the simplest. This consists of first filtering
the urine through filter paper, then pouring some of the clear urine
into a test tube, holding the test tube in a flame so that only the
upper layer boils, then adding a few drops of 2% solution of acetic
acid and boiling again. If there is albumen present, a very faint, or
a heavy cloudiness (precipitate of coagulated albumen) forms on
boiling and persists or becomes heavier on the addition of a few drops
of dilute acetic acid (2%) and boiling again. If a precipitate occurs
at the first boiling, but clears up again entirely on adding acetic
acid, it is not albumen but harmless phosphates or carbonates.
HELLER'S TEST FOR ALBUMEN
Into a test tube pour a few drops of nitric acid, filter the urine and
allow a small quantity of it to trickle from a pipette down the side
of a test tube until it comes in contact with the acid. If albumen is
present a distinctly formed white ring is seen at the zone of contact.
TEST FOR INDICAN
This material is found in cases of obstinate constipation and in other
intestinal disturbances where the passage of the food mass in the
small intestines is delayed and the putrefactive bacteria exert their
activities upon the unabsorbed protein.
~Test.~--Mix equal quantities of urine and fresh hydrochloric acid and
add drop by drop fresh concentrated solution of chloride of lime (5 to
1,000). Indican is indicated by the appearance of a blue color.
SUMMARY
~Urinalysis~ represents one of the most important means for
determining the health of an individual, since it is the urine that
shows those substances produced in the body as a result of the
breaking down of the body tissues and protein foods.
~Composition of Normal Urine~ must be familiar to the nurse in order
that she may recognize any change taking place in the urine of her
patient which may indicate pathological conditions in the body.
~The Specific Gravity~ of urine is one of the points by means of which
the presence of certain substances more or less abnormal in character
is determined.
~Other Points~, such as color, odor, quantity, reaction, and chemical
composition, likewise show any deviation from the normal in the
individual.
~Urine Tests~ are necessary to determine the composition of the
secretion. The character of these tests and the methods used in making
them form an essential part in the training of the nurse.
~Tests~ for the presence of albumen, sugar, and possibly indican in
the urine, should be made by the nurse. The latter substance
represents the extent of putrefaction taking place in the body and for
this reason should be included in the urine tests.
~Collecting the Urine~ for testing is important. The amount includes
all that has been voided throughout the entire twenty-four hours
beginning after the bladder has been emptied on the first morning and
ending after the first specimen has been voided on the morning of the
second day.
~Preserving the Urine~ for testing is usually necessary, especially
during the warm weather. The specimens should be collected in a
wide-mouthed sterile glass jar. This should be kept in a cold place.
Some harmless preservative such as chloroform should be added to
assure its keeping.
PROBLEMS
(a) Outline tests used in urinalysis; state when they are used.
(b) List the equipment needed for making the simple tests.
(c) Make tests in laboratory and list results in note-book.
FOOTNOTES:
[110] "Treatment of Diabetes Mellitus," pp. 182-183, by Joslin.
[111] "Starvation (Allen) Treatment for Diabetes Mellitus," by Hill
and Eckman.
[112] "Treatment of Diabetes Mellitus," p. 186, by Joslin.
[113] "Chemistry for Nurses," by Reuben Ottenburg.