Urinalysis: Physical Examination Of Urine
Overview
Urinalysis is a diagnostic test that involves analyzing a person's urine sample. The purpose of urinalysis is to check for various health conditions such as urinary tract infections, kidney diseases, and diabetes. During the test, the urine sample is examined for the presence of certain substances such as proteins, glucose, and red or white blood cells. Urinalysis is a non-invasive and relatively simple test that can provide valuable information about a person's health. It is often used as a screening tool in routine check-ups or when a person is experiencing symptoms that may indicate a urinary tract or kidney problem.
Physical Examination
Introduction
The initial step in a routine urinalysis is the physical examination of urine. This may seem like a straightforward procedure, but it requires expertise and experience. The physical examination provides preliminary information about the urine sample, which aids in the subsequent urinalysis. For instance, if the urine appears white and cloudy, it may indicate the existence of leukocytes (pus cells) and/or epithelial cells in the microscopic analysis. In addition, a positive result for nitrite in the chemical examination may also be indicative of the presence of these cells.
In addition, a positive nitrite result may be found in the chemical examination.
1. Volume
On an average day, a person typically urinates between 600 to 2000 milliliters of urine. The amount of urine produced by the body is influenced by a number of factors such as how much fluid a person drinks, their body temperature, the climate they are in, and their overall health condition. These factors can affect the amount of urine produced by the body over a 24-hour period.
Abnormal amounts of urine that are either higher than 2000 ml/24 or lower than 600 ml/24 are mostly caused by pathological conditions.
Test Procedure
To measure the volume of urine, a patient must collect a 24-hour urine sample in a container provided by the laboratory technician. The container should be clean, dry, and brown in color to avoid exposure to direct sunlight and chemical reactions. It should also contain an appropriate preservative for the desired urine chemical test or be refrigerated after each urine collection. The container should be labeled on the wall with the patient's name, collection time and date, type of chemical test ordered, and preservative used. Urine volume is measured using a graduated cylinder and recorded in ml/24 hr.
Clinical Significance
Polyuria is a condition where an individual excretes more than 2000 ml of urine consistently over a prolonged period of time. This condition is used to evaluate fluid balance and kidney function. Polyuria can occur due to various reasons such as
● diabetic mellitus
● diabetic insipidus
● certain tumors of the brain and spinal cord,
● and acromegaly.
Diuresis refers to an increased production of urine, which can be caused by drinking too much fluid. On the other hand, oliguria is a condition where the body produces consistently low amounts of urine, usually less than 400 ml in a day. This can occur due to dehydration or reduced blood supply to the kidneys caused by conditions such as •prolonged vomiting
•diarrhea
• other factors that cause obstruction of the urinary tract.
Oliguria may also be caused by
•heart problems
•kidney diseases
•fasting
•excessive salt intake.
Anuria refers to the complete absence of urine excretion, which means that a person is producing less than 100 ml of urine per day. This condition can occur due to
● a complete blockage in the urinary tract
● acute renal failure
● acute glomerulonephritis
● hemolytic transfusion reaction
● other medical conditions.
On the other hand, polyuria is a condition characterized by excessive urine output. This can happen due to various physiological reasons such as
● consumption of intravenous glucose or saline
● coffee
● alcohol
● tea
● caffeine
● certain medications like thiazides and other diuretics.
2 Odor
Fresh urine from healthy individuals typically has a slight smell due to volatile acids, such as ammonia, that are present in the urine.
Test Procedure
The test involves using the sense of smell to examine urine, and the outcome is determined by the technician's interpretation of the odor.
Clinical Significance
The smell of urine can indicate various conditions such as aging, disease or dietary intake.
● If the urine specimen is old, i.e. If urine is left out for more than 2 hours after collection, it can have an ammonical odor due to bacterial breakdown of urea into ammonia. The ammonical odor result to break down and conversion of urea in the urine into ammonia by the action of bacteria.
● Cystinuria and homocystinuria can result in sulfurous odor
● Oasthouse urine disease has a yeast-like smell.
●Tyrosenemia is characterized by cabbage or fishy odor
● presence of ketone bodies due to various factors such as diabetes can produce a fruity odor.
● Butyric/hexanoic acidemia can result in a urine odor resembling sweat.
● infants with inherited amino acid metabolism disorders can have urine that smells like burnt sugar or maple.
● The consumption of asparagus can also produce a characteristic urine odor, but this has no clinical significance.
3. Foam
Normally, when urine is collected in a container, it creates a small amount of white foam. However, under certain abnormal physiological and metabolic conditions, the amount and color of the foam can change. When there is a high amount of bile pigment in the urine, the foam increases and becomes yellowish in color. This could suggest the presence of bilirubin in the urine, but it's not a conclusive test. It's important to perform a chemical analysis of the urine to confirm the presence of bilirubin.
4. Color
The color of urine can change throughout the day. When you wake up in the morning, it may appear darker yellow. But as the day progresses, it usually becomes lighter, ranging from pale yellow to almost clear. The normal range of urine color is from light yellow (resembling straw) to dark yellow (resembling amber).
When urine appears light yellow in color, it indicates that it is more diluted and has a low specific gravity. However, in cases of diabetes mellitus, despite the urine appearing light yellow in color, it has a high specific gravity due to the high concentration of glucose present in it.
Dark amber or dark yellow color in urine generally means that the urine is concentrated and has a high specific gravity. This is a normal occurrence and is often observed during the first urination in the morning.
The normal color of urine is the result of three pigments: urochrome, uroerythrin, and urobilin.
•Urochrome is the primary pigment responsible for the yellow color of urine and is found in greater proportion than the other two pigments.
•Uroerythrin contributes to the red color of urine.
•urobilin is responsible for the orange-yellow color.
Together, these pigments give urine its characteristic color.
Procedure of the Test
When a urine sample is collected, its color should be recorded by looking at it immediately after it has been voided. If the color of the urine sample is not recorded within 30 minutes of collection, chemical reactions may occur which can cause the color of the urine to change. This can result in inaccurate reporting of the urine sample's color. Therefore, it is important to record the urine sample's color promptly to avoid any false reports.
Clinical Implication
An experienced laboratory technician can predict possible findings in the chemical and microscopic examination of urine by observing its color. The abnormal color of urine can vary depending on the constituents of urine.
When your urine is pale or colorless, it could indicate several things.
One possible reason could be that you have been consuming a lot of fluids, causing your body to expel excess water.
Another possible reason could be diabetes mellitus or diabetes insipidus, two medical conditions that affect the body's ability to regulate fluid balance.
Alcohol consumption can also lead to pale urine, as can nervousness.
In summary, if you notice that your urine is pale or colorless, it's worth considering whether any of these factors could be contributing to the change in color.
Dark yellow or brownish-red urine could be a sign of various conditions such as highly concentrated urine, lower intake of fluids, dehydration, fever, or the use of certain urinary tract medications like phenazopyridine. In addition, a yellow-brown or "beer brown" color of urine may indicate the presence of bilirubin.
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