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Urinalysis Lab

(Simulation)

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What is Urinalysis?

Urinalysis is the evaluation of urine’s physical properties, chemistry, and suspended components using three methods of clinical examination.

Macroscopic Method

The macroscopic method evaluates factors that can be observed without using instruments, including volume, clarity, color, and odor.

Macroscopic exam of a urine sample by a clinician
A urine sample is examined for volume, clarity, color, and odor.

Urine volume is typically determined on a specimen collected over a 24-hour period and ranges from 750ml to 2000ml. Low urine volume can indicate possible chronic kidney disease. High urine volume can indicate diabetes, high fluid intake, or possible kidney disease.

Urine clarity is an evaluation of its turbidity. Urine is typically clear, and cloudy urine can suggest a urinary tract infection (UTI), kidney stones, or type 2 diabetes.

Slide the blue circle to change the clarity of the urine sample.

Urine color is normally pale yellow. However, changes in color can result from particular foods, dehydration, infections, and medications.

Urine ColorCauses
Pale to dark amberDehydration
Red or pinkBlood in urine or particular foods
OrangeMedications, carotene (carrots), B vitamins, or liver disease
Blue or greenFood coloring, medications, or UTIs
BrownFava beans, medications, kidney disease, or muscle breakdown

Urine odor is typically slight but can vary with dehydration, diabetes, medications, infections, and particular foods.

Urine OdorCauses
AmmoniaDehydration
Sweet or fruityDiabetes
Strong smellParticular foods, medications, or UTIs
Chemical Method

The chemical method uses prepared test strips to evaluate urine pH, specific gravity, and the level of certain diagnostic chemical compounds.

The test strips are typically narrow ribbons of plastic with several (up to 10) absorbent pads attached to one side. The pads contain chemicals that react and change color after being immersed in urine. It can take 30 to 120 seconds for the compounds in the urine to begin reacting with the reagents on the test pads. 

Typically, a single strip can test for leukocytes, nitrite, urobilinogen, proteins, pH, blood, specific gravity, ketones,  bilirubin, and glucose.

Urine test strip illustraton
Urine Test Strip

Manufacturers usually package several urine test strips in a single bottle-like container. A diagnostic chart is on the outside of the container. It contains rows of colored squares and associated test values. 

After immersing the test strip in a urine sample, a clinician will compare the colors of the reagent pads to the corresponding color chart.

Bottle of urine test strips
Urine Test Strips and Container

Test reports commonly contain quantitative and semi-quantitative values. The quantitative report values use standardized numerical units, and the semi-quantitative values use words or non-standardized units. The units used to report quantitative values include g/l, mmol/l, and μmol/l. In contrast, semi-quantitative values include Trace, 1+, 2+, 3+ and 4+.

Urine test strip color chart
Urine Test Strip Color Chart

Color changes in the test strip pads indicate possible health conditions such as diabetes, metabolic abnormalities, liver diseases, kidney and urinary tract disorders, and urinary tract infections.

Color ChangesIndications
Elevated Leukocyte (esterase) or nitrites.Urinary tract infection (UTI)
Elevated UrobilinogenLiver dysfunction
Elevated ProteinKidney damage
Low pHKidney stones
Elevated BloodKidney damage, infection, kidney or bladder stones, kidney or bladder cancer, or blood disorders.
Specific gravityHydration level
Elevated Ketones or GlucoseDiabetes
Microscopic Method

The microscopic method uses light microscopy to identify suspended elements such as urinary casts, cells, crystals, and microorganisms. 

After centrifuging, a small sediment sample is placed on a glass slide, coverslipped, and moved to the microscope stage, where the urine is initially examined at 30X magnification. 

Casts are relatively large cylindrical structures in the urine. The most common type of cast consists of proteins secreted from the distal convoluted tubule and collecting ducts of nephrons. Casts can also contain erythrocytes, leukocytes, epithelial cells, and fat globules. When they are present in high numbers, they indicate kidney disease. 

Cells usually are present in urine in small numbers. An abundance of renal tubular epithelial cells indicates damage to the renal tubules. Too many white blood cells or red blood cells indicate a possible bacterial urinary tract infection (UTI) or inflammation of the urinary tract or kidneys. 

Crystals appear when the urine is over-saturated with certain types of substances. The accumulation of crystals could cause stones that block the urinary tract passageways, UTIs, and kidney infections. The most common crystals are created by ….

Struvite (magnesium ammonium phosphate crystals)
Uric acid
Calcium oxalate dihydrate
Cystine 
Bilirubin
Calcium carbonate

Microorganisms such as bacteria, fungi, and parasites indicate UTIs and kidney infections.

Subject InfoSubject information icon

Your subject is 40 years old and works from home as an accountant. Since moving into a management position, her hours have increased, and getting enough exercise has become an increasing problem. She has gained 50 pounds over the past several years as a result. Your subject also reports that she has to urinate frequently and is often hungry, thirsty, and fatigued.

Urine test strip simulation subject, urinalysis test  subject

Your subject is visiting your clinic for a physical exam. Her last exam was performed several years ago but indicated she was in good health. 

As a part of your subject’s exam, you have decided to include urinalysis. Your subject last urinated about 30 minutes before arriving at your clinic.

Procedures Test procedures icon

Macroscopic

Prepare Sample for Observations

After collecting a urine sample from your subject, remove the lid from the container so you can note the urine’s volume, clarity, and color.

Chemical

Immerse Test Strip

Take hold of the gripping surface at the top of a test strip and remove it from the bottle. Slowly submerge the test strip into the urine sample, ensuring you cover the entire surface of each test square.

Once you’ve saturated the strip, remove it from the container and turn it horizontally. In this position, any excess urine will drain away and ensure that the reactive chemicals don’t run from one square to another. Wait 2 minutes for any reactions to occur.

Results Test procedures icon

Macroscopic

Determine Urine Clarity

Use the comparison slider shown below to determine the clarity of the urine test sample.

Urine clarity - clear
Urine Test Sample

Determine Urine Color

Use the comparison slider shown below to determine the subject’s level of hydration.

Urine clarity - clear
Urine Test Sample

Chemical

Determine Abnormalities

Compare the test squares to the standardized color chart to determine if any abnormalities are present. Read the test strip squares in chronological order. Check the value of the last square (the one furthest from your hand), then move on to the next until you’ve reviewed the entire strip.

Microscopic

View Suspended Components

The urine test sample examination found no suspended particles, crystals, microorganisms, or cells.

AnalysisAssessment icon

Describe the color, clarity, and volume of your subject’s urine sample.

Volume – high, considering the subject urinated just before arriving at your location. 

Clarity – clear. 

Color – relatively light.

Based on the strip test results, what is your preliminary diagnosis?

Your subject’s urine contains an abnormally high amount of glucose (+++ or 60 mmol/l). Glucose starts appearing in the urine (glucosuria) when the blood glucose level exceeds about 160–180 mg/dL. This appears to be a relatively new condition, which indicates type 2 diabetes mellitus.

How does your subject’s urine volume relate to your diagnosis?

When the level of glucose in the urine is elevated, it osmotically draws water into the urine from the kidney tubules. This increases urine volume (polyuria).

What does your subject’s urine color indicate about her level of hydration? Why, should your subject be concerned about hydration?

Your subject appears to be properly hydrated. People with type 2 diabetes urinate frequently, which explains your subject’s increased sense of thirst. Your subject needs to drink more fluids to prevent dehydration.

Is the specific gravity reading high or low? Offer a possible explanation for this reading.

Specific gravity is a measure of urine concentration, and it is somewhat low (1.005). Your subject’s urine is light in color, which indicates a low particle concentration.

How do your subject’s lack of exercise and weight gain relate to your diagnosis?

Both are associated with increased insulin resistance and type 2 diabetes.

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Attributions & ReferencesAttribution icon

American Family Physician – Urinalysis: A Comprehensive Review

Cornell University of Veterinary Medicine – Urinalysis

Medical News Today – Urine Crystals

ScienceDirect – Urinary Casts

University of California San Francisco – Urinary Casts 

WebPath (University of Utah) – Urinalysis

Wikipedia – “Clinical urine tests