Laboratory Report on Urine Examination

When testing urine the test results may provide information regarding the status of carbohydrate metabolism and kidney function.

The kidney glomeruli act as ultrafilters for the plasma protein; however as much as 150 mg/dl of protein may normally be excreted into the urine. In glomerular proteinuria, an increase in glomerular permeability occurs, resulting in an increase of urine proteins. High urine protein concentration therefore may indicate proteinuria.

Blood glucose concentration above the renal threshold will overflow into the urine. This situation normally arises in diabetes patients. In renal diabetes, the renal threshold is reduced to the point where sugar appears in the urine despite normal levels being present in the blood. In both situations, monitoring of urine glucose becomes important.

In the following exercises it will be determined, by using three simulated urine specimens, what color, pH, specific gravity, glucose, and protein has on urine. Urine Normal is normal, and Urine high (positive) on all tests. In part 2, unknown simulated urine will be tested and determine the probable disorders.

Materials and Methods: Part 1

Color: Record the color of each simulated urine (Low, Normal, and High) in Table 1.

pH: 1. Obtain three pH indictor strips and label each to match the containers (L,N,H).

2. Test each simulated urine (Low, Normal, and High) by dipping the appropriate pH strip into it

three consecutive times.

3. Shake off excess liquid and compare the color of the strip to the colors on the pH chart. The

color that most closely matches your strip corresponds to the pH of the simulated urine.

4. Record each pH in Table 1.

The pH of normal urine averages 6.0, which is slightly acidic. Certain foods and diseases that can affect urine pH.

Specific Gravity

1.The instructor will either instruct you to calibrate the hydrometer or provide you with a calibration factor. Record the calibration factor in Table 1.

2.Obtain the urine hydrometer and jar and rinse both pieces well. Fill the jar three-fourths full of Urine Low. 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 the measured (base) urine specific gravity in Table 1.

3.The instructor will give instructions on whether to add or subtract from the reading of the calibration factor. Record the adjusted urine specific gravity in Table 1.

4.Remove the hydrometer and pour the simulated urine sample back into the container.

5. Rinse the hydrometer and jar well.

6. Repeat steps 2 to 5 with Urine Normal and Urine High.

Specific gravity varies according to fluid intake and can also be affected by diseases.

Glucose

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 gently to mix the contents. Caution: do not allow the contents of the vial to come into contact with your skin or eyes. Compare the color to the Clinitest® color chart.

5. Record the results of the test for glucose (positive or negative) in Table 1. 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.

Protein

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 reagent.

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 a pale violet indicates the presence of protein.

5. Record the results of the test for protein (positive or negative) in Table 1.

Normally, protein should not be detected in the urine.

Results:

Urine Test Low Normal High Urine A Urine B

Color Light Yellow Light Yellow Clear (White) Clear (no color) Pink

pH 3 7 8 5 8

Specific gravity:

Base 1.02 1.025 1.029 1.032 1.034

Glucose Negative Negative Present Present Negative

Protein Negative Negative Negative Negative Positive

Table 1

Discussion:

From the above data, it can be determined that not all of the urinalysis results were normal. The sample Urine High and Urine A is positive for diabetes mellitus. The sample of Urine B could belong to someone who is on a high protein diet, starvation, fasting or has severe anemia.

Results:

Test Tube Color

Begin Color Change Contain Protein Digestion

# 1 Clear Cloudy, Light purple No

# 2 Clear Same, Light purple No

# 3 Clear Same, Light pink/purple Yes

Discussion:

From the above data, it is obvious that test tube # 3 is positive for protein digestion. Enzymes all work best at an optimum temperature that is usually body temperature at 37ºC. If the temperature that the enzyme has to work at gets too high, normally 40ºC it will start to become denatured and therefore no longer work on its substrate as the active site has changed shape. In addition, enzymes usually work best at an optimum pH level, this is normally seven because enzymes are proteins which are damaged by very acidic or very alkaline conditions.

The hypothesis is proven that when both hydrochloric acid and pepsin is combined that it effectively digests protein.