sp15 week12 urinary system physiology

Urinary System Physiology - 1

Background: Urinary System Physiology

PREPARATION Read Chapters 18 19. Watch lecture videos on D2L: Week11A G Read the background provided here. OBJECTIVES The objectives for this weeks laboratory are to:

Evaluate how different drinks affect the characteristics (i.e. concentration and volume produced) of urine.

Collect and analyze the results of a urinalysis test. Conclude and defend your results of 5 urinalysis case studies.

Background Reading The production of urine is a complex process that is highly regulated and performs many functions in the body (including the filtration and excretion of wastes, osmoregulation, and maintenance of plasma volume). Many factors can affect this process including the amount and type of beverages that you consume. In todays lab we will be exploring: 1) How common beverages affect the volume and concentration of the urine that is excreted. 2) How to perform a basic urinalysis with microscopic examination.

A urinalysis is a simple, yet, powerful laboratory tool that is often used to gather information on a patients carbohydrate metabolism, kidney and liver function, and/or acid-base balance to diagnose and monitor the progression of many diseases, such as diabetes, liver disease, and urinary tract infections. The simplicity of this test allows it to be used in a variety of medical settings, such as doctors offices, urgent care facilities, and hospitals. Physical examination of the urine Color-The color of urine is usually described after visual inspection with common color terms like clear, pale straw, light yellow, light amber, dark amber, red, or other. Since these terms are subjective and take some training to recognize, we will be using the adjacent color chart for uniform data collection. Turbidity Normally, freshly voided urine is clear. When urine is allowed to stand, amorphous crystals, usually urates, may precipitate and cause urine to be cloudy. The turbidity of urine should always be recorded and microscopically explained. If a fresh sample is cloudy (turbid) it may be an indicator of infection. Turbidity is recorded as clear or cloudy.


Volume Urinary volume is dependent upon fluid intake; amount of solutes to be excreted; loss of body fluids by normal processes, such as perspiration and respiration, and abnormal processes, such as diarrhea, and cardiovascular and renal function. Although the volume of a random specimen is clinically insignificant, the volume of the specimen received should be recorded for purposes of documentation and standardization. Urine volumes can be measured two ways: volumetrically or by mass. We will be using mass. The volume is estimated by weighing the urine sample in a tared container and assuming that 1g = 1mL of urine. Specific Gravity As light moves from air (low density) to water (high density), the speed of the light wave slows down and causes the light wave to bend. The more concentrated the solute, the more the light bends. By comparing the amount light bends through a known solution of water to an unknown solution, we can measure the density of the solution. Refractometers can relate the density of a solution to specific gravity in a ratio of: Density of solution = Specific Gravity Density of water So if the solution has the same density as water, the specific gravity would be 1.000 g/ml. However, as the amount of solute increases in the solution, so does the specific gravity. Therefore, higher specific gravity of the urine indicates more concentrated urine which could be due to water conservation by the kidney. The refractive index scale can be calibrated to measure the specific gravity of most urine samples up to 1.036 g/ml. Chemical Testing of the Urine Reagent-strip Testing A plastic strip is used, which contains pads that contain the reagents that react with various urine components and change color. The strip is dipped into the urine and the colors on the pads can be read manually by comparison with color charts or with the use of automated machines that examine the color change. The observation of color change must be performed at the specific times indicated on the test strip instructions. The test strips we will be using measure the following values:

1. pH 2. Proteins 3. Glucose

4. Ketones 5. Blood and

myoglobin

6. Bilirubin 7. Urobilinogen 8. Nitrites

The specific gravity is determined by where the start of the blue field intersects the specific gravity scale. The specific gravity of this sample is approximately 1.026. Note: The refractometers we use in lab have the specific gravity scale on the right side!


Microscopic Examination of Urine Sediment Clinical Significance of Microscopic Examination As part of a urinalysis, the urine sediment is centrifuged and examined microscopically for crystals, casts, red blood cells, white blood cells, and bacteria or yeast. In healthy people, the urine contains small numbers of cells and other formed elements from the entire urinary tract, and epithelial cells from the kidney, ureter, bladder, and urethra. In renal disease, the urine often contains increased numbers of substances discharged from an organ that is otherwise accessible only by biopsy or surgery. A microscopic examination of urine sediment detects the presence and amounts of the following clinically significant components:

Red and white blood cells Bacteria and yeast Casts Epithelial cells Crystals

Examination of urinary sediment provides a direct sampling of the cells and debris from the urinary tract and it provides important information useful for both diagnosis and prognosis. Leukocytes - Normally, 0 to 3 leukocytes per high-power field (40x objective) will be seen on microscopic examination. More than 3 cells per high-power field probably indicates disease somewhere in the urinary tract. Erythrocytes - Normally there should be only an occasional red blood cell in the urine (2-3 per high-power field). If erythrocytes are found, it is important to estimate the count and rule out an underlying cause. In women, it is important to make sure that the urine specimen was not contaminated by the menstrual flow. Inserting a tampon and collecting urine midstream are ways to prevent contamination. Erythrocytes may be differentiated from white blood cells in several ways:

1. White blood cells are larger than red blood cells. 2. When focusing with the high-power lens, the red blood cells appear as a bi-concave

without a nucleus; the white blood cells tend to appear granular with a visible nucleus.

General rules to be followed when performing urine reagent strip testing.

1. Do NOT touch the test strip to the side of the container!

2. Make sure you have a timer and read the boxes at the appropriate times

3. Beware of interfering substances. Certain drugs and dietary factors can alter results.

4. Understand the advantages and limitations of the test. Positive results from reagent-strip testing may require confirmation with chemical and microscopic methods.


Epithelial cells- Some epithelial cells from the skin surface, renal tubules, or outer urethra can appear in the urine. These cells are large, flat, and quite common. Bacteria and Yeast - Urine stored in the bladder is normally free of bacteria or yeast. However, bacteria are commonly found in urine specimens because of the abundant normal microbial flora of the vagina or external urinary meatus and due to the ability of bacteria to multiply rapidly in urine standing at room temperature. As a result, bacteria noted on a microscopic examination should be interpreted in view of clinical signs and symptoms of urinary tract infection. Diagnosis of bacteria in a patient with a suspected urinary tract infection requires a urine culture and sensitivity. Mucus- This is a common finding in urine sediment. It looks like long, ribbon threads and is secreted by glands in the lower urinary tract.

Crystals- Sediment and crystals are solids found in urine. Some forms of crystals appear in the urine of healthy individuals. Abnormal crystals can indicate liver disease or some forms of genetic abnormalities. CastsThese urinary sediments are formed by coagulation of protein or cells in the kidney tubules. Casts are cylindrical and vary in diameter. The sides are parallel, and the ends are usually rounded. Casts in the urine always indicate some form of kidney disorder and should always be reported. If casts are present in large numbers, the urine is almost sure to be positive for albumin. There are seven types of casts. They are as follows:

Hyaline casts Red cell casts White cell casts

Granular casts Epithelial casts Waxy casts

Fatty casts

Urine Handling Precautions: As with all human bodily fluids, there is a chance of transmission of infectious diseases. As a result, you should always wear latex gloves when handling urine samples and DO NOT touch table surfaces, lab manuals, or writing utensils while you have gloves on.

Testing Procedures Supplies needed:

Refractometer Disposable pipette ChemWipes Absorbent paper for desktop

Latex gloves Ethanol

Biohazard waste receptacle

1. Pick up the refractometer and lift the cover of the refractometer. 2. If there is any liquid in the refractometer, wipe it away gently with a soft

absorbent paper. 3. Draw up 1 or 2 drops of urine into a pipette. 4. Place one drop of urine into the refractometer and close the cover gently.


5. Dispose of the pipette into the Biohazard bag. 6. Hold the end of the refractometer with the eyepiece up to your eye and point the other end

towards the light. 7. Looking through the eyepiece, you will see several grids. The refractometer bends the light

through the urine and produces a line on a scale where the white areas and blue areas intersect.

8. The Specific Gravity will be displayed in the scale on the far right. Report this value as the refractometer specific gravity to your data recorder, who should write it in the data table.

9. Open the cover and carefully wipe away the urine from the refractometer surface. 10. After the final sample is measured, wipe the sample surface with ethanol to clean any urine

residue. Chemical Test Strip Testing Procedures Supplies needed:

Urinalysis testing strips Disposable pipette Absorbent paper for desktop

Latex gloves Biohazard waste receptacle Timer

Be familiar with these instructions before you begin!

Timing is critical for this exercise.

Assign different jobs in the group. You will need a timer, a tester and a data recorder.

1. Check that you have all of your necessary supplies before you open your urine sample. 2. Tester: Put on latex gloves. 3. Gently mix the urine sample before testing with the test strip. 4. Remove a test strip from the bottle and replace the cap. 5. Observe the important time intervals that you need to measure the samples as listed on

the color chart. Check with your timer before you proceed. 6. Dip all of the test strips into the urine to wet each pad and immediately remove the strip.

Timer: start the time. 7. Gently tap the strip on the absorbent paper to remove the excess urine. 8. Hold the test strip near the color blocks on the bottle. Keep the bottle and the test strip

level (horizontal) or the color will bleed between the color blocks. 9. Do NOT let the test strip touch the bottle! 10. Hold the test strip near the laminated color block and compare each test pad to the

corresponding row of color blocks. Be sure and read each pad at the time shown! 11. Hold the test strips close to the color and match them as precisely as possible. 12. Report the lab results to your data recorder.

a. Do not record them yourself until after your gloves are removed and your hands are washed.


Preparing a slide for Microscopic Examination We will be preparing 2 different samples for microscopic examination. Supplies at the slide station: Disposable pipette Sedistain

Cenislide tube and cap Cenislide Microscope stage holder

Glass microscope slide a cover slip

Sharpie

Cenislide centrifuge Preparing a slide using the CeniSlide system 1. Obtain a clean centrifuge tube and cap. 2. Pipette the urine from the bottom of the sample into a centrifuge tube to the fill line. 3. Add one drop SediStain to the centrifuge tube. 4. Secure the cap on the tube, label the tube with your table number, and place it in the

centrifuge at the front desk. Always place tubes in opposite pairs so the rotor is balanced. 5. The instructor will check that the centrifuge is balanced and then spin the tubes for the

required time. 6. When you retrieve your centrifuge tube, place the tube into the microscope slide holder for

examination. 7. After viewing your sample in the microscope, dispose of your slide and all urine-

contaminated items in the large red biohazard container in the lab.

Preparing a Microscope slide 1. Place a SMALL drop of Sedistain on a clean microscope slide. 2. Very carefully draw up 1 or 2 drops of the urine sample from the bottom of the container

into a pipette. 3. Place a drop over the drop of Sedistain from #1. If there is any sample left in the pipette,

return it to the sample tube. 4. Gently lower a cover slip onto the droplet. 5. Dispose of the pipette into the Biohazard container. 6. Set up your microscope with high contrast by closing the iris diaphragm and lowering the

condenser of the microscope.


Laboratory Procedures Urine Handling Precautions: As with all human bodily fluids, there is a chance of transmission of infectious diseases. As a result, you should always wear latex gloves when handling urine samples and DO NOT touch table surfaces, lab manuals, or writing utensils while you have gloves on. EXERCISE 1: The Effects of Beverage Intake on Urine

At the very beginning of lab, all of the subjects will be asked to go to the bathroom and empty their bladder. This sample will not be saved.

1. Your TA will post the first name, weight (kg), height (cm), age, and sex for each subject volunteering for this experiment. Be sure to record these data in the spaces provided on your data sheet.

2. After 30 minutes, each subject will collect his or her baseline (time 0) sample in a clean, dry beaker that has been previously weighed.

a. The subject will go to the bathroom and urinate into the beaker, catching all of the urine while trying to completely empty the bladder.

b. The subject will bring the entire sample back to the lab where it will be measured. 3. At this time, the subjects will be given their drinks, which must be consumed in 5 minutes.

Note the time the beverages are completed as time 0. 4. Be sure and keep track of time and take your urine samples at 30-minute intervals for a total

of 4 samples (including the initial sample). 5. For each sample you will need to record the following:

Total Urine Sample mass (g): Before you begin, you need to zero (tare) the scale. Place the beaker in the scale and record the mass in Table 2. (1 g =1ml) Urine color: Compare the color to the color chart and record your observations. Specific Gravity: Test the specific gravity using the refractometer.

6. Make sure all of the data were recorded correctly for that sample and dispose of the urine by pouring it into the large collection container on the front desk.

7. Rinse and dry the beaker and place it on the absorbent paper. 8. Repeat the previous steps for the other samples. 9. After collecting a sample at all time intervals, make two graphs showing urine volume over

time and specific gravity over time. Insert these graphs into your electronic data sheet in the location specified.

EXERCISE 2: Urinalysis with Microscopic Examination 1. Get one volunteer from each table to obtain a free-catch, midstream urine sample in the

bathroom using the Urine sample collection instructions on the next page. 2. Your TA will divide up the samples and bring one to your table. 3. For your sample you will need to do the following:

Subject Reminder: Subjects should limit fluid and salt intake on the day of the experiment and do not drink anything 2 hour prior to lab.


Urine sample collection Collect a sample of urine in a clean or sterile

container. About 1 - 2 ounces of urine is needed for a test.

Remove the container from the urine stream without stopping the flow. You may finish urinating into the toilet bowl.

Replace the cap and bring the sample to the lab and place the sample in the ice chest outside the lab next to the door.

a. Record urine color and turbidity: Compare the color to the color chart and record your observations.

b. Specific Gravity: Test the specific gravity using the refractometer.

c. Follow the Chemical Test Strip Testing Procedures.

4. Record your results in Table 3 of your data sheet.

How to scan your glass slide under the microscope: 1. Place the glass slide under the scope

and begin the examination under low power.

a. Be sure to use low light (adjust the iris and condenser). Too much light makes the cellular and crystalline elements harder to see.

b. Scan the slide under low power to locate areas of interest. Look for casts just inside the perimeter of the cover slip.

2. Then switch to 40X magnification and examine ten random fields in the central part of the coverslip.

a. Count the numbers of red blood cells and white cells in each and report the range of findings. If the field is covered with cells, report as "TNTC" (too numerous to count) or "packed."

b. Record these results in Table 4 of your data sheet. 3. Make a sketch on the data table of any sediment particles you find.

a. Label your sketched items as cells, crystals, droplets, or artifacts. b. The Explanation of Urinalysis Results section of the lab manual contains pictures of

the most common things you may see on the urine. 4. Repeat Steps 1-3 for the CeniSlide tube and record your results in Table 5 of your data sheet. EXERCISE 3: Case Studies Use the patient profiles in your data sheet to complete the Case Studies in your data sheet. CLEAN UP

Make sure you are finished with your sample. Pour the urine sample into a waste container at the front desk. This waste container will be flushed down the toilet at the end of the lab.

Dispose of your glass slides and cover slips in the sharps container. Disposable items such as urine sample containers, absorbent paper, gloves, and pipettes will

need to be disposed of in the biohazard bags. Place all glassware that is reused (like beakers) in the 10% bleach solution in the 5-gallon

bucket at the front of the room. Make sure the refractometer is clean and dry. Wipe down microscopes with alcohol pads. Spray and wipe all surfaces with disinfectant. Replace absorbent paper on all surfaces.


Section no. __ Group Member Names (last, first): Place an * after the name of the typist

LABORATORY DATA SHEET FOR TAKING NOTES AND DRAFTING YOUR RESPONSES

EXERCISE 1: The Effects of Beverage Intake on Urine Table 1: Subject Data

Subject #1: Consumes small volume of water First Name: Sex: Wt. (kg): Ht. (cm): Age:

Subject #2: Consumes large volume of water First Name: Sex: Wt. (kg): Ht. (cm): Age:

Subject #3: Consumes Gatorade

First Name: Sex: Wt. (kg): Ht. (cm): Age:

Subject #4: Consumes Gatorade with salt First Name: Sex: Wt. (kg): Ht. (cm): Age:


Table 2: The effects of beverage intake on the urine volume, color, and specific gravity

Elapsed time (min)

Subject

Total Urine

sample mass (g)

Beaker weight

(g)

Urine volume (ml)

(Total urine sample beaker

weight)

Urine color

Specific gravity

0

Subject #1 Subject #2 Subject #3 Subject #4

30


60


90


Using the data in Table 2, create two graphs USING EXCEL depicting the four subjects urine volume over time and the four subjects specific gravity over time. Be sure to include a legend and proper figure title. Insert these graphs here: Insert Graphs here 1. Describe the trends in the graphs of urine volume and specific gravity between the 4 subjects

in Exercise 1.


2. Compare the urine results from 2 water subjects. Which had the highest urine volume?______ Which had the lowest specific gravity? ___________ Is this what you expected? Why or why not? Explain.

3. Compare the urine results from the Gatorade subjects. Which had the highest urine

volume?______ Which had the lowest specific gravity? ___________ Is this what you expected? Why or why not? Explain.

EXERCISE 2: Urinalysis with Microscopic Examination

Table 3: Chemical Test Strip Testing


Table 4: Microscopic Examination of Sediment on glass slide with stain

Field RBC's WBC's Other

1

2

3

4

5

Slide 1

Sketch area:


Table 5: Microscopic Examination of Sediment on CeniSlide

Field RBC's WBC's Other

1

2

3

4

5

Slide 1

Sketch area:


EXERCISE 3: Case Studies Use the following patient histories and urinalysis results obtained for the following individuals to answer the corresponding questions in terms of how the kidney works. There is a table outlining the clinical significance of each test on the last page which will be very helpful for this exercise. Patient A- This patient is a 25-year-old male who is complaining that he needs to go all of the time, but only produces a small amount of urine each time (


Patient B- This patient is a 28-year-old male with a height of 57 and weight of 357 lbs. He complains of insatiable thirst, frequent urination and lethargy. Test parameter Patient values Normal Sample volume 3.8 L in 24 hours Color Yellow Specific gravity 1.025 1.001-1.035 pH 6.0 4.6 to 8

Glucose (mg/dl) 500 negative (less than

30mg/dl) Protein (mg/dl) 8 less than 15mg/dl

Ketones (mg/dl) 15 negative (less than2mg/dl

acetacetoacetic acid) Bilirubin (mg/dl) negative Negative Nitrites Negative Negative Leukocytes Negative negative Blood Negative negative Sediment analysis Few cells and casts

6. List the abnormal findings. 7. What is your diagnosis? ____________________ What other tests could you perform to

confirm your diagnosis? 8. Why do you think this patients urine volume is so high?


Patient C- This patient is an 18-year-old female who has come in for a routine physical exam. She is asked for a urine sample and has great difficulty producing a small amount of urine despite not having urinated for several hours. She reported having 2 cups of coffee and a donut for breakfast about 6 hours ago, but nothing else to eat all day. Test parameter Patient values Normal Sample volume 0.05 L Color Very dark Specific gravity 1.030 1.001-1.035 pH 6.5 4.6 to 8 Glucose (mg/dl) Negative negative (less than 30mg/dl) Protein (mg/dl) Negative less than 15mg/dl Ketones (mg/dl) Negative negative (less than2mg/dl

acetacetoacetic acid) Bilirubin (mg/dl) Negative negative Nitrites Negative Negative Leukocytes Negative Negative Blood Normal Negative Sediment analysis Contained few nucleated cells

9. List the abnormal findings. 10. What do you think is wrong with this patient? Explain.


Patient D- This patient is a healthy 19-year-old male that wrestles competitively and has provided a urine test following his wrestling competition. His normal body weight is 185 lbs., but for this competition, he competed in the 172-lb. weight class. Test parameter Patient values Normal Sample volume Normal Color Pale and hazy Specific gravity 1.01 1.001-1.035 pH 6.8 4.6 to 8 Glucose (mg/dl) Negative negative (less than 30mg/dl) Protein (mg/dl) Trace less than 15mg/dl Ketones (mg/dl) 30 negative (less than2mg/dl

acetacetoacetic acid) Bilirubin (mg/dl) Negative Negative

Nitrites Negative Negative Leukocytes Negative Negative Blood Negative Negative Sediment analysis Few casts

11. List the abnormal findings. 12. How are ketones generated? 13. Can you explain the abnormal findings in this patients urine?


Patient E- This patient is a 38-year-old vegetarian. He is complaining of mild irritation during urination.

14. What type of crystals are described in the sediment analysis? 15. List the abnormal findings. 16. How does this patients diet affect his urinalysis?


Conclusions 1. Hormonal control of water and ion reabsorption in the kidney helps us regulate the specific gravity and volume of urine excretion. How does the body control urine output and concentration? 2. How do the different beverages alter the blood plasma osmolarity and ultimately the urine output and specific gravity? Be sure to include how changes are sensed by the body and how it responds to maintain homeostasis. 3. The following table represents the osmotic solution values in mOsm-units: SOLUTION OSMOLARITY [mOsm] Water 10-20 Sweat 170-220 Gastric Fluids 280-303 Blood Serum 300 Gatorade** 290-303 Pepsi-Cola 568 Coca-Cola 650 Fruit Juice 690 Explain why fruit juice, Coca-Cola, or Pepsi-Cola would not be effective in rehydrating a dehydrated person.


Physical Examination Results

Test Normal ranges Clinical significance

Urine Color

Clear, Hazy or

Straw (for our lab it is a number)

The color of urine is related to its concentration. The color of non-pathological urine varies widely from colorless to deep yellow; the more concentrated the urine, the deeper the color. By-products from the breakdown of hemoglobin are present in the urine and can greatly affect the color. Furthermore, some dietary factors can alter the color of the urine (ie. Multi-vitamins, vegetables and some food dyes). For instance, students who take B-vitamin supplements will have their urine quickly turn bright yellow following ingestion of Vitamin B.

Turbidity

Clear, (should NOT be cloudy!)

Normally, freshly voided urine is clear. When urine is allowed to stand, amorphous crystals, usually urates, may precipitate and cause urine to be cloudy, so the time the sample was taken and the time it was analyzed should be considered. If a fresh sample is cloudy (turbid) it may be an indicator of infection and should always be followed up by a microscopic exam to explain the turbidity!

Volume varies Although the volume of a random specimen is clinically insignificant, the volume of specimen received should be recorded for purposes of documentation and standardization.

Test Normal ranges Clinical significance of Chemical test strip results

pH 5.0 to 9.0 Measurement of urinary pH is a useful for managing renal stones or crystals. Uric acid stones form in acidic urine and are more soluble in alkaline urines. Alkaline urine will precipitate calcium or calcium phosphate crystals, while acidic urine

will tend to dissolve them.

Protein up to 100 mg /day

Protein is not normally present in urine because it is too large to pass through the filtration barrier. Most of the urine protein is albumin from the plasma. Smaller-molecular-weight proteins such as globulins may also be present in urine. Proteinuria (excess urinary protein) can be the result of either increased filtration at the glomerulus or decreased tubular reabsorption. Protein in urine can be seen with vigorous exercise, muscle wasting, and pregnancy. It can also result from bacterial infection and glomerular damage. Renal disease can cause the filtration barrier to become leaky to protein, which increases glomerular filtration and can also lead to increased urine volume.

glucose not

normally present

Glucose is not normally present in the urine because it is completely reabsorbed in the proximal tubule. Temporary elevation of glucose excretion measurable by test strips can occur after treatment with some drugs, cases of shock and

during pregnancy. Repeated positive testing is almost always diagnostic for diabetes. Glucose in urine attracts water by osmosis, increasing the urine volume. Diabetics urinate frequently and are excessively thirsty as a result.


Ketones not

normally present

Ketones are by-products of the metabolism of fat. Ketosis and ketonuria (excess ketones in the urine) are characteristic of starvation, various metabolic disorders, and diabetes. For diabetics the production of ketones results from the inability to properly regulate insulin, which plays a key role in the metabolism of fats. This catabolism is incomplete, resulting in the

formation of large amounts of ketones.

Blood and Myoglobin

not normally present

Blood, often referred to as occult blood (meaning mysterious origin), indicates bleeding somewhere in the urinary system and is an abnormal finding. A positive test indicates the presence of red blood cells in the urine (hematuria), free

hemoglobin in the urine (hemoglobinuria), or rapid breakdown of muscle (myoglobinuria). The peroxidase assay cannot distinguish between the presence of hemoglobin or myoglobin in urine, so a positive test should be followed with other

testing including a sediment analysis.

Bilirubin not

normally present

Red blood cells in the body live for about 120 days, after which time they are broken down and the hemoglobin they contain recycled in a complex process that results in formation of bilirubin. Bilirubin is formed in the liver and excreted with the bile into the intestine. The presence of bilirubin in the urine indicates blood levels that are too high, either because excessive numbers of red blood cells are being broken down (hemolytic anemia, infection or exposure to lysing agent) or because the liver is failing to properly metabolize the hemoglobin (hepatitis, cirrhosis, or bile blockage due to gall stones).

Uro-bilinogen

2 to 10 mg/L

This is another by-product of the breakdown of hemoglobin. A fresh specimen is essential because it is a light-sensitive compound. Due to the variable excretion pattern and the rapid breakdown in light, the clinical value of this test is controversial and all significant results should be confirmed by other methods.

Nitrite not

normally present

Normally there is no nitrite in urine, which is a product of the bacterial reduction of nitrate. Therefore, a positive result is indicative of a bacterial infection. If this is associated with painful urination, the infection is located in the lower urinary tract (urethra or bladder). Infections in the kidney do not normally produce pain during urination. The amount of nitrite

formed depends on many things, including the type of bacteria, how long the urine is stored in the bladder, and the presence of nitrate in the diet.

Leukocyte not

normally present

The intensity of the color reactions is proportional to the number of leukocytes in the specimen. The assay will detect both lysed and intact leukocytes. Urine specimens that are test positive by the reagent strip test need to be examined microscopically.

Specific Gravity

1.000-1.035

This is an estimate of specific gravity that is measured using special indicators whose colors vary from blue-green to yellow-green. However, this is an estimate and abnormal results should be confirmed using specialized equipment.


Microscopic Examination

image Clinical significance of Microscopic Examination

Leukocytes

Associated with the inflammatory process in or adjacent to the urinary tract. Presence of many WBCs in urine, especially in clumps, is strongly suggestive of acute infection such as pyelonephritis, cystitis, or urethritis.

Erythrocytes

RBCs normally dont appear in urine, but presence of 1-2 RBCs per high powered field is not abnormal. High amounts of RBCs needs to be evaluated as it could be benign as an unclean catch from a female during menstruations or something more serious such as hematuria.

Mucus

Mucus is a normal finding and is not clinically significant.


Test Image Clinical significance of Microscopic Examination

Hyaline casts

Hyaline casts are the most frequently occurring casts in urine. They are colorless, homogeneous, transparent, and usually have rounded ends. These may be increased after strenuous exercise and are formed when protein solidifies in the nephron.

Red cell casts

Red cell casts indicate renal hematuria. Red blood cells may stick together and form red blood cell casts that can appear brown to almost colorless. The presence of oddly shaped red blood cells in the urine suggests a glomerular disease such as glomerulonephritis, as the odd shape is caused by the passage of the cells through a distorted and abnormal glomerular structure.

White cell casts

White cell casts are present in renal infection and in noninfectious inflammation. The majority of white blood cells that appear in casts are hypersegmented neutrophils.

Granular casts

Granular casts almost always indicate significant renal disease. Granular casts that contain fine granules may appear grey or pale yellow in color. Granular casts that contain larger coarse granules are darker. These casts often appear black because of the density of the granules.

Waxy casts

Waxy casts result from the degeneration of granular casts. Waxy casts have been found in patients with severe chronic renal failure, malignant hypertension, and diabetic disease of the kidney. Waxy casts appear yellow, grey, or colorless. They frequently occur as short, broad casts, with blunt or broken ends, and often have cracked or serrated edges.

Epithelial cast

Epithelial casts are rarely seen in urine because renal disease that primarily affects the tubules is infrequent. Few epithelial cells may often be observed as a result from sloughing of old cells. A significant increase may be indicative of inflammation of the urinary tract in the area from which the cells are derived.. Epithelial casts may

be arranged in parallel rows or haphazardly.

Fatty casts

Fatty casts are seen when there is fatty degeneration of the tubular epithelium, as in degenerative tubular disease. Fatty casts also result from lupus and toxic renal poisoning. A typical fatty cast contains both large and small fat

droplets. The small fat droplets are yellowish-brown in color.


Test Image Common Crystals found in Microscopic examination of Urine

Amorphous urates

Amorphous urates are normal in urine. Appearance: often appear in noncrystalline amorphous form. Have yellowish-brown (pinkish) granular

appearance. In urine with uric acid in it, amorphous urates will precipitate out of solution upon refrigeration. They appear

as a heavy pink sediment and impart acloudy to turbid appearance of the mixed urine. Amorphous urates will re-solubilize when heated at 60oC

Triple Phosphate Crystals

Common, colorless, coffin-lid prism Can be present in neutral and alkaline urines. Frequently found in normal urine but can also form urinary calculi.

.

Calcium oxalate

Colorless octahedrons found in acidic urine. Calcium oxalate crystals in the urine are the most common constituent of human kidney stones that can obstruct tubules, causing significant damage and pain. Twelve

percent of males form stones, with those between the ages of 30 and 50 at greatest risk for stone disease. Oxalate is common in nuts and dark green leafy vegetables. It is the reason rhubarb leaves are considered toxic. When pets or children drink antifreeze, oxalate is formed from the ethylene glycol in antifreeze by metabolism in the

liver. In both cases, kidney failure due to massive tubular damage is the cause of death. To avoid kidney stones, at risk individuals are urged to keep urine volumes high, and oxalate levels and urine pH low. This reduces the

concentration and increases solubility of calcium oxalate in tubular fluid.

Uric Acid

Uric acid is the final oxidation product of purines, a natural substance found in food. Food items like meat, dried beans, anchovies, sea fish, oatmeal, etc. are purine rich and over-consumption of purine rich foods increases uric

acid levels in the body. If it reaches above the specified limit, the condition is known as hyperuricemia. Small crystals pass through urine and the severity of symptoms vary with increase in uric acid content of urine.

Most common disorders associated with high levels of uric acid are gout, Lesch-Nyhan syndrome,

cardiovascular disease, diabetes, uric acid stone, urolithiasis, and metabolic syndrome.

Hippuric

Hippuric not often diagnosed in urine analysis, but they are often associated with a neutral pH. Associated with diets high in fruits and vegetables that contain large quantities of benzoic acid


Ca Phosphate

These crystals may be present in normal urine, but they may also form calculi.

Ca Carbonat

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Calcium carbonate crystals are normal in urine Appearance: small, colorless granules or dumbbells.

Not clinically significant but can be confused with other elements. A unique feature of calcium carbonate is that the crystals effervesce with hydrochloric acid or acetic acid. This can help to confirm the presence of calcium

carbonate in the urine.

Ammonium Biurate

Ammonium biurate crystals are normal in urine. Appearance: yellowish-brown, can be seen in a "thorn apple" shape (round with thorny projections) or in

spherical form. Ammonium biruate crystals can be seen in normal urine. However, the presence of ammonium biurate crystals

especially in combination with a urine pH 9.0 or higher usually indicates an old or poorly preserved specimen. Best practice is to NOT report any urinalysis results on the sample as it has been compromised. A recollect

should be requested.

Bilirubin

Bilirubin crystals are abnormal crystals in urine. Appearance: Yellow-brown needles or granules. They are frequently attached to the surface of cells.

Bilirubin crystals are seen in several hepatic disorders. The appearance of bilirubin crystals should be accompanied by a positive biochemical test for bilirubin (reagent

test pad and Ictotest).

Cystine

Cystine Crystals are abnormal in urine. Appearance: colorless, thin, hexagonal plates

Cystine crystals are found in the inherited condition, cystinuria. Cystine crystals are the most frequent cause of kidney stones in children.

The presence of cystine crystals should be confirmed by cyanide-nitroprusside test (turns red-purple)

Leucine crystals are abnormal in urine Appearance: yellow-brown spheroids with concentric rings around the outer edge and radial striations in the

center. Leucine crystals may be seen in liver disorders in which amino acid metabolism is impaired.

The presence of leucine crystals is often accompanied by a positive biochemical test for bilirubin and is often accompanied by tyrosine crystals in the same sediment.


Tyrosine crystals are abnormal in urine Appearance: colorless to yellow-brown single needles. Also seen as sheaves or rosettes.

Tyrosine crystals may be seen in tyrosinemia and in certain liver disorders in which amino acid metabolism is impaired.

The presence of tyrosine crystals is usually accompanied by a positive biochemical test for bilirubin and are often accompanied by the presence of leucine crystals in the sediment.

Sulfanomide crystals are considered abnormal in urine. Appearance: flat needles, sheaves of small needles or as spheroids. Often brown in color.

The presence of sulfanomide crystals usually indicates administration of the drug and not necessarily a pathological condition. However, their presence is also associated with kidney stone formation.

Cholesterol crystals are abnormal in urine Appearance: clear, flat plates with notched corners.

The appearance of cholesterol is associated with the Nephrotic Syndrome. Cholesterol crystals are accompanied by a positive biochemical test forprotein. They usually appear after the

urine sample has been refrigerated and may be accompanied by oval fat bodies, fatty casts, and free fat droplets in the sediment.

Background: Urinary System PhysiologyTable 1: Subject Data

sp15 week12 urinary system physiology

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