Urinalysis

Urine is a complex mixture of organic and inorganic solutes in water. Since urine is derived from blood which has travelled throughout the body, urinalysis can point to problems in many other systems besides the urinary system. Physical and chemical characteristics of urine are used to point to abnormalities.

Many of the tests to be performed will utilize test strips. These test strips have been impregnated with chemicals which react with chemicals in the urine. By comparing the color of the strip with standard colors, the amount of various chemicals in the urine can be determined. The tests do not have to be performed in order.

Exercise 34.1

Collect a urine specimen in a clean jar just before class starts. You should fill the jar approximately two thirds full.

Examine the physical appearance of the urine and record your observations. Compare your results with the values shown.

Color. Normal urine is amber to straw colored due to a pigment called urochrome which is a breakdown product of hemoglobin in the blood:

hemoglobin hematin bilirubin -> urochromogen urochrome.

The following colors are indications of unusual chemicals in the urine:

Milky white - pus, bacteria, chyle

Reddish yellow urobiligen from bacteria acting on bile or porphyrin from cirrhosis of the liver or jaundice

Brownish yellow or green - bile pigments

Reddish brown - blood

Certain foods such as carrots, beets, rhubarb and some drugs and vitamin supplements can color the urine without indicating pathology.

Transparency. Swirl your specimen and observe its transparency. Normal urine is clear (not cloudy). Cloudy urine may indicate minerals, pus, bacteria, chyle, or mucus. You will examine the urine microscopically later for these solids.

Specific Gravity. Specific gravity is a determination of the density of a substance. For liquids, the specific gravity is dependent upon the amount of solute dissolved in the water. Specific gravity is also dependent upon temperature. Specific gravity of urine is determined using a urinometer (see Figure 34.1) which is composed of a cylinder and a hydrometer. The hydrometer floats in urine in the cylinder. The greater the specific gravity, the higher the hydrometer will float. Calibrations on the stem of the hydrometer allow one to determine the specific gravity of the urine. A 24-hour, normal urine specimen has a specific gravity of 1.010 to 1.030, while single samples may range from 1.001 to 1.060.

Exercise 34.2

Before you use the hydrometer practice reading the sample drawings in Figure 34.1.

Fill the cylinder two thirds full of well mixed urine. Remove any foam with a piece of paper towel. Slowly insert the hydrometer so that it does not hit the bottom. Read the hydrometer.

Take the temperature of the urine. Record the temperature.

Wash the urinometer pieces with soap and water.

Calculate the correct specific gravity by adding 0.001 for each 3° C above 25° C or subtracting the same amountfor each 3° below 25° C. Record the adjusted specific gravity.

How Read Urinometer

1.000

Ejo ^20

1.000

y.oofl

Wil '201

1.000

Read the hydrometer at the bottom of the meniscus (curve in the surface of the urine). Note the location of the decimal point.

Figure 34.1 Urinometer Cylinder Hydrometer Urinometer

Hydrogen Ion Concentration. Hydrogen ion concentration is measured by using pH paper. An acid pH is below 7.0, while an alkaline pH is above 7.0. Freshly collected urine has a pH between 4.5 and 8.0. The pH varies during the day and with diet. High acidity can indicate acidosis, fever, and high protein diet. Alkalinity can indicate retention in the bladder, anemia, and gastric ulcers.

Exercise 34.3

Dip a piece of pH (nitrazine) paper into the urine. Shake off the excess urine.

Immediately compare the color of the paper with the standards on the container.

Record the pH.

Proteins, Normally large amounts of protein are not found in urine. We will test for one protein, albumin. Certain conditions such as a high protein diet and cold baths, as well as toxemia, anemia, and kidney congestion, can result in albumin in the urine.

Exercise 34.4

Swirl the sample of urine and insert an Albustix test strip and immediately compare the color with the standards on the bottle.

Record your results.

Bilirubin. Bilirubin is formed from the breakdown of hemoglobin from red blood cells. It is normally present in small quantities in the urine. Large amounts may indicate malfunction of the liver.

Exercise 34.5

Use the Ictotest to test for bilirubin,

Place the square, absorbent test mat on a paper towel

Place ten drops of urine onto the center of the test mat

Shake one Ictotest tablet into the jar lid. Transfer the tablet onto the center of the moistened mat DO NOT HANDLE

THE TABLET WITH YOUR FINGERS.

IMMEDIATELY CLOSE THE BOTTLE.

Place one drop of water onto the tablet Wait 5 seconds and place another drop of water on the tablet so that the water runs off the tablet onto the mat

A blue or purple color indicates the presence of bilirubin in the urine; a pink or red color should be ignored.

Blood. Blood is not normally found in urine, though the urine may be contaminated with blood at the time of collection from menstruating females.

Exercise 34.6

Use a Hemastix test strip to test for the presence of blood. Dip the test strip into well-mixed urine and remove immediately. While removing, run the edge of the strip against the edge of the container to remove excess urine.

Exactly 60 seconds after removal, compare with the standards on the bottle. Record your results.

Glucose. The amount of glucose excreted by the kidney is very small, no more than 0.03 g/dl. Excess glucose in the urine often indicates diabetes mellitus.

Exercise 34.7

Swirl the sample of urine and dip in a Clinistix test strip. Tap off excess urine on the rim of the container. After ten seconds, compare the color with the standards. Record your results.

Ketones. Ketones are an intermediate product in the breakdown of fatty acids by cells. When there is inadequate carbohydrate in the body, there is increased lipid catabolism. As fat catabolism increases, the level of ketones in the blood increases. This condition is called ketonuria. Some of the excess ketones are eliminated in the urine. Ketonuria is often a symptom of diabetes mellitus.

Exercise 34.8

Swirl the urine and dip in a Ketostix test strip. Fifteen seconds after wetting the test strip, compare it with the standards on the bottle. Record your results.

Microscopic Examination. This is the most critical part of urinalysis. Microscopic examination of the urine may reveal excess minerals, leukocytes, or bacteria. An abundance of leukocytes can indicate a urinary tract infection.

Exercise 34.9

Swirl the urine and pour 5 ml into a centrifuge tube. Insert the tube into the centrifuge. Balance the tube with another tube containing urine or water on the other side of the rotor.

Centrifuge the tube for five minutes at 1500 rpm.

Carefully pour off the liquid without disrupting the sediment.

Add 2 drops ofSedi-stain (to improve the visibility of cells etc.).

Thoroughly mix the contents by flicking the bottom of the tube wth your finger.

With a wire loop, transfer two loops of sediment to a clean glass slide. Add a cover slip.

Examine the specimen under low and high power. Refer to Figure 34.2 to identify objects in the sediment.

Figure 34.2 Urine Sediment calcium phosphate epithelial cells cholesterol calcium oxalate

Figure 34.2 Urine Sediment calcium phosphate epithelial cells cholesterol calcium oxalate

Epithelial Cell Sketch

ammonium-magnesium phosphate pus cast mucus threads uric acid leukocytes (pus)

2. Transparency

Circle one: Transparent (clear) Translucent (cloudy)

3. Specific gravity

Adjustment factor_

Adjusted specific gravity_

5. Albumin Circle one: negative trace + ++ +++ ++++

6. Bilirubin Circle one: absent present

7. Blood Circle one: negative trace small moderate large

9. Ketones Circle one: negative trace small moderate large 10. Microscopic examination Sketch the contents of the urine:

For Instructor-provided "unknown":

2. Transparency

Circle one: Transparent (clear) Translucent (cloudy)

3. Specific gravity

Adjustment factor_

Adjusted specific gravity_

5. Albumin Circle one: negative trace + ++ +++ ++++

6. Bilirubin Circle one: absent present

7. Blood Circle one: negative trace small moderate large

9. Ketones Circle one: negative trace small moderate large

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Responses

  • Tewolde
    What power objective should be used to examin urine?
    5 years ago
  • ROMA
    How to read urinometer?
    3 years ago
  • tiblets
    How to measure specific gravity of urine using urinometer?
    3 years ago
  • tanta brandybuck
    How to read urinometer in urine specimen?
    2 years ago
  • Pervinca
    How do you compute the temperature at which ypur specimen is read in the urinometer?
    2 years ago

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