Examination of Urine
By:Terry Kotrla, MS, MT(ASCP)
Professor
Austin Community College
Urine Color
* Normal urine color ranges from pale yellow to deep amber — the result of a pigment called urochrome
o B vitamins turn urine an eye-popping neon yellow BUT may also indicate liver disease.
o porphyria, a disease that affects your skin and nervous system, turns urine the color of port wine.
Urine Color
* Most changes in urine color are harmless and temporary and may be due to:
o Certain foods – beets may turn urine red
o Dyes in foods/drinks
o Supplements – vitamins
o Prescription drugs
* Unusual urine color can indicate an infection or serious illness .
Suggested Colors
* pale yellow (straw)
* light yellow
* yellow
* green-yellow (olive)
* red-yellow
* red
* red-brown
* brown-black
* black
* milky
Examples of Urine Color
Urine Clarity
* During the visual inspection, the MLT observes the urine's and determines how clear it is (its clarity).
* Urine clarity refers to how clear the urine is.
* Terms used: clear, slightly cloudy, cloudy, or turbid.
* “Normal” urine can be clear or cloudy.
* The clarity of the urine is not as important as the substance that is causing the urine to be cloudy.
Urine Clarity
* Substances that cause cloudiness but that are not considered unhealthy include:
o mucous,
o sperm and prostatic fluid,
o cells from the skin,
o normal urine crystals, and
o contaminants (like body lotions and powders).
* Other substances that can make urine cloudy (such as red blood cells, white blood cells, or bacteria) indicate a condition that requires attention.
Examples of Urine Clarity
Urine Color and Clarity
* Urine color and clarity can indicate what substances may be present in urine.
* Confirmation of suspected substances is obtained during the chemical and microsopic examination.
Chemical Examination
* Reagent strips are used only once and discarded.
* Testing
o Perform within 1 hour after collection
o Allow refrigerated specimens to return to room temperature.
o Dip strip in fresh urine and compare color of pads to the color chart after appropriate time period.
o Instruments are available which detect color changes electronically
Using Reagent Strips
* BRIEFLY dip the strip in urine.
* Colors are matched to those on the bottle label at the appropriate times.
* Timing is critical for accurate results.
Reagent Strips
Glucose
* Presence of glucose (glycosuria) indicates that the blood glucose level has exceeded the renal threshold.
* Useful to screen for diabetes.
Bilirubin
* Bilirubin is a byproduct of the breakdown of hemoglobin.
* Normally contains no bilirubin.
* Presence may be an indication of liver disease, bile duct obstruction or hepatitis.
* Since the bilirubin in samples is sensitive to light, exposure of the urine samples to light for a long period of time may result in a false negative test result.
Ketones
* Ketones are excreted when the body metabolizes fats incompletely (ketonuria)
Specific Gravity
* Specific gravity reflects kidney's ability to concentrate.
* Want concentrated urine for accurate testing, best is first morning sample.
* Low – specimen not concentrated, kidney disease.
* High – first morning, certain drugs
Blood
* Presence of blood may indicate infection, trauma to the urinary tract or bleeding in the kidneys.
* False positive readings most often due to contamination with menstrual blood.
Ph
* pH measures degree of acidity or alkalinity of urine
Protein
* Presence of protein (proteinuria) is an important indicator of renal disease.
* False negatives can occur in alkaline or dilute urine or when primary protein is not albumin.
Urobilinogen
* Urobilinogen is a degradation product of bilirubin formed by intestinal bacteria.
* It may be increased in hepatic disease or hemolytic disease
Nitrite
* Nitrite formed by gram negative bacteria converting urinary nitrate to nitrite
Leukocytes
* Leukocytes (white blood cells) usually indicate infection.
* Leucocyte esterase activity is due to presence of WBCs in urine while nitrites strongly suggest bacteriuria.
Normal Values
* Negative results for glucose, ketones, bilirubin, nitrites, leukocyte esterase and blood.
* Protein negative or trace.
* pH 5.5-8.0
* Urobilinogen 0.2-1.0 Ehrlich units
Handling and Storage of Strips
* Handling and Storage
o Keep strips in original container
o Do not touch reagent pad areas
o Reagents and strips must be stored properly to retain activity
+ Protect from moisture and volatile fumes
+ Stored at room temperature
o Use before expiration date
Procedure
* Dip strip briefly, but completely into well mixed, room temperature urine sample.
* Withdraw strip.
* Blot briefly on its side.
* Keep the strip flat, read results at the appropriate times by comparing the color to the appropriate color on the chart provided.
Sources of Error
* Timing - Failure to observe color changes at appropriate time intervals may cause inaccurate results.
* Lighting - Observe color changes and color charts under good lighting.
* QC - Reagent strips should be tested with positive controls on each day of use to ensure proper reactivity.
* Sample - Proper collection and storage of urine is necessary to insure preservation of chemical.
Sources of Error
* Testing cold specimens - would result in a slowing down of reactions; test specimens when fresh or bring them to RT before testing
* Inadequate mixing of specimen - could result in false reduced or negative reactions to blood and leukocyte tests; mix specimens well before dipping
* Over-dipping of reagent strip - will result in leaching of reagents out of pads; briefly, but completely dip the reagent strip into the urine
Examination of Urine
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