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Urinalysis Lab Workbook Share Documents and Files


The Kidneys
Urine, a metabolic waste product, is produced in the kidneys, two bean-shaped organs located on either side
of the spine just above the waistline. The kidneys are well protected from bruising by a thick capsule of fat.
The kidneys, along with the skin and lungs, are excretory organs.

The kidneys function as filters of the blood. Approximately one-fourth of all the blood from the heart flows to
the kidneys through the large renal arteries. Substances in the blood are either retained or filtered out into
the urine through a capillary network. The kidneys can either concentrate or dilute the urine with these waste
substances, thus balancing the body's internal environment. Urine passes through tubules in the kidneys to
the ureter, which leads to the urinary bladder, a storage organ. Stored urine is then voided through the

Our lives depend upon the proper functioning of the kidneys and urinary system. The functional state of the
kidneys can be assessed by physical, chemical, or microscopic examination of the urine (urinalysis), which has
been practiced by doctors for over 5000 years. Before modern techniques were developed, doctors used
appearance, odor, and taste of urine as indicators of health and disease. Today urinalysis is used to diagnose
kidney disease, to follow the treatment of kidney disease, and to diagnose other disorders that affect the

Urine Tests
Normally, urine consists of 95% water and 5% solids such as urea and sodium chloride. Almost all substances
found in urine are also found in blood but at different concentrations. Some substances such as glucose have a
renal threshold that must be exceeded before the substance is excreted. Presence of such substances in the
urine usually indicates disease.

This exercise teaches five important tests routinely done in clinical urinalysis: color, pH, specific gravity,
glucose, and protein.

    10-ml graduated cylinder                                          Clinitest Tablets with Chart
    Urine Specimen Containers                                         Glass Vials
    Jumbo pH Strips, Wide Range                                       Biuret Reagent
    Urine Hydrometer and Jar Sets                                     Pipets

* Because urine may contain bacteria, thorough hand washing is needed at the completion of the exercise *

Normal urine colors range from light yellow to amber, depending upon the concentration of urochrome, the
urinary pigment. Lighter or darker urine can be caused by foods, drugs, or diseases (Table 2).
    1) Obtain a specimen container and collect a fresh urine specimen of approximately 25 ml.
    2) Record the color of your urine specimen in Table 1 (Urine Test Results). Table 2 lists normal and
       abnormal urine colors and possible causes.
The pH of a solution is a measure of the free hydrogen ion (H+) concentration, which indicates acidity or
alkalinity. A solution with a pH of 7.0 is neutral, one with a pH less than 7.0 is acidic, and one with a pH greater
than 7.0 is alkaline. The pH of normal urine averages 6.0, which is slightly acidic. Foods and diseases that can
affect urine pH are listed in Table 3.
    1) Obtain a pH indicator strip and test your urine by dipping the pH strip into it three consecutive times.
    2) Shake off excess urine and closely compare the color of the strip to the colors on the pH chart. The
        color that most closely matches your strip corresponds to your pH.
    3) Record your pH in Table 1.

Specific Gravity
Specific gravity is the density of a solution compared to water, which has a specific gravity of 1.000. The
specific gravity of normal urine ranges from 1.010 to 1.025. Specific gravity varies according to fluid intake and
can also be affected by diseases (Table 3).
   1) Obtain the urine hydrometer and jar and rinse both pieces well. Fill the jar 3/4 full of urine. Place the
        hydrometer in the jar so that it is not touching the sides and read the level of urine on the hydrometer
        scale. Record your measured (base) urine specific gravity in Table 1.
   2) Remove the hydrometer and pour your urine back into the specimen container.
   3) Wash the jar and hydrometer well with soap and water.

Glucose (sugar) should not be detected in normal urine. The presence of glucose usually indicates diabetes
mellitus, a severe metabolic disorder due to defective carbohydrate utilization. See Table 3 for causes of
glucose in the urine.
    1) Using a dropping pipet, place 5 drops of urine into a glass vial.
    2) Rinse the dropper thoroughly with water and add 10 drops of water to the vial.
    3) Drop one Clinitest tablet into the vial. Place the vial on the tabletop and observe the reaction.
               Caution: the glass vial will become very hot during the chemical reaction.
    4) After the reaction has stopped, wait 15 seconds. Shake the vial gently to mix the contents. Compare
       the color to the Clinitest color chart.
               Caution: do not allow the contents of the vial to come into contact with your skin or eyes.
    5) Record the results of the test for glucose (positive or negative) in Table 1.

A very small amount of protein is normally present in the urine. The biuret reagent causes a color change in
the presence of excessive protein. Both diet and disease can affect protein level in the urine. Factors
associated with excretion of protein into the urine are listed in Table 3.
    1) Using a 10-ml graduated cylinder, add 1 ml urine to a clean glass vial.
    2) Rinse the graduated cylinder and measure 2 ml biuret reagent (note the pale blue color of the biuret
    3) Add the biuret reagent to the urine vial.
    4) Gently swirl the vial to mix the contents. After 10 minutes hold the test tube against a white
        background and observe the color. A color change from light blue to pale violet indicates the presence
        of protein.
    5) Record the results of the test for protein (positive or negative) in Table 1.
                                                    Table 2
                                       Urine Colors and Possible Causes

       Color                           Diet                           Drugs                        Disease

Light yellow to amber                 Normal

                                                                                           Uncontrolled diabetes
Clear to light yellow                 Alcohol               Phosphate, carbonate

Yellow orange to dark                                                                     Bilirubin from obstructive
                                      Carrots                      Antibiotics
        green                                                                                      jaundice

  Red to red brown                    Beets                         Laxatives               Hemoglobin in urine

                                                                                          Unhemolyzed red blood
    Smokey red                        Beets                      Anticonvulsants
                                                                                          cells from urinary tract

     Dark wine                        Beets                Anti-inflammatory drugs           Hemolytic jaundice

                                                                                           Melanin pigment from
    Brown black                      Rhubarb                     Antidepressants

       Brown                         Rhubarb                      Barbiturates            Anemia or liver infections

       Green                      Green food dyes                    Diuretics               Bacterial infection

                                                    Table 3
                             Abnormal Urinalysis Results and Possible Causes

                    Test Result                           Diet                          Disease

                                                    High protein diet,           Uncontrolled diabetes
                  Low pH (<4.5)
                                                     cranberry juice                   mellitus

                                                Diet rich in vegetables,
                  High pH (>8.0)                                                     Severe anemia
                                                    dairy products

          Low Specific Gravity (<1.010)         Increased fluid intake            Severe renal damage

                                                Decreased fluid intake,          Uncontrolled diabetes
         High Specific Gravity (>1.025)
                                                     loss of fluids              mellitus, severe anemia

                                                                                 Uncontrolled diabetes
                 Glucose Present                       Large meal
                                                                                 mellitus, severe anemia

                  Protein Present                     Protein diet                   Severe anemia
                                                                     Names _____________________________

                              Urinalysis                                     _____________________________
                                                                                                   Period _____

                                                 Table 1
                 Urine Test                   Student Results                     Normal Results

                   Color                                                      Yellow to amber

                    pH                                                               4.6-8.0

              Specific gravity                                                     1.010-1.025

                  Glucose                                                           Negative

                  Protein                                                           Negative

  1) Are your urinalysis results normal? If not, which tests were abnormal and what might this indicate?

   2) The following abnormal results were obtained from a patient's urinalysis:

            Color: very light yellow                     Glucose: positive
            pH: 3.0                                      Protein: negative
            Specific gravity: 1.040

       Name a disease that could cause these results.

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