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.