Basic Examination of the Urine Specimen Phlebotomy and Medical Laboratory Technology Program Faculty Austin Community College

Introduction All specimens must be properly labeled The laboratory request slip must accompany the specimen The patient’s name The patient’s identification number The date The time of collection The type of specimen The attending physician’s name The label should be affixed on the container, not the lid.

The Urine Sample Collection and Preservation of Urine Types of Specimens & Containers Urine collected anytime of the day or night can be used for routine urinalysis testing, BUT the sample collected the first thing in the morning is preferred as it is the most concentrated. Containers must be clean and single use (disposable). If urine is to be cultured for bacteria, the container must be sterile. Sample cup for routine testing

The Urine Sample Collection and Preservation of Urine Types of Specimens When special tests, usually performed in the chemistry department are ordered, the urine sample is usually collected over a 24 hr. period of time. 24 hour urine collection container.

The Urine Sample Handling and preserving specimens Urine samples must be examined within 1 hour of collection OR be refrigerated. For routine testing, the refrigerated sample must be tested within 8 hours. Never leave a urine sample sitting out at room temperature more than 1 hour. Bacterial growth in the sample destroy or change important chemicals and elements.

Testing the Urine Sample Color of urine Yellow –Some shade of ‘yellow’ is the typical color of urine. dilute urine is usually lighter in color; concentrated urine is usually dark Urochrome – pigment that gives urine its yellow color Certain foods, supplements, prescription drugs, etc. may cause harmless temporary changes in urine color. Most common colors Light yellow (may be called pale yellow or straw) Yellow Dark yellow

Testing the Urine Sample Other colors of urine May or may not indicate a disease process Amber – a deep yellow-brown or green-brown color. Although not always pathological, often associated with increased bilirubin and seen in liver conditions such as hepatitis or cirrhosis. Red – may have blood present Brown/black – may be associated with melanoma Port wine color – result of a ‘porphyria’ - a rare metabolic condition that affects skin and nervous system Neon-yellow – often seen in persons taking B vitamins

Examples of Urine Color

Testing the Urine Sample Urine Clarity or Transparency Refers to how clear is the urine sample Technician swirls the sample in the cup and with a good background light source, looks through the specimen. Terms to describe clarity: clear, hazy, cloudy and turbid. Fresh urine is usually clear to hazy. Fresh urine that is cloudy often indicates a bacterial infection (the cloudiness due to presence of white blood cells). Things that make urine hazy: mucous, sperm / prostatic fluids, skin cells, urine crystals, & contaminates such as body powders, etc.

Examples of Urine Clarity/Transparency

Testing the Urine Sample Chemical Examination of Urine Reagent strips Test pads are for pH, protein, glucose, ketone, bilirubin, blood, urobilinogen, specific gravity, leukocytes and bacteria Used only once and discarded Performing the chemical tests by reagent strip Perform within 1 hour after collection OR Allow refrigerated specimens to return to room temperature Dip strip in fresh urine and compare color of pads to the color chart after appropriate time period Instruments are available which detect color changes electronically

Testing the Urine Sample Urine Multistix This product made by Siemans Bayer corp.

Testing the Urine Sample Chemstrip Urine Test Strips This product is made by Roche-Diagnostics

Testing the Urine Sample Follow manufacturer’s directions, regardless of whose product you are using When reading dipstick results manually; colors are matched to those on the bottle’s label; timing is critical for each pad.

Chemical Exam of Urine Multistix

Chemical Exam of Urine

Procedure Normal dipstick procedure: Dip strip briefly, but completely into well mixed, room temperature urine sample. Withdraw strip, blot briefly on its side Keeping the strip flat, read results at the appropriate times by comparing the color to the appropriate color on the chart provided.

Chemical Exam of Urine Sources of error (& preventions) Failure to observe color changes at appropriate time Failure to observe color changes under good lighting 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

Chemical Exam of Urine Handling and Storage Keep strips in original container, stored at RT Protect from moisture and volatile fumes Use before expiration date Do not touch reagent pad areas

Chemical Exam of Urine Precautions (again) Reagent strips should be tested with positive controls on each day of use Failure to observe color changes at appropriate time intervals may cause inaccurate results Reagents and strips must be stored properly to retain activity Observe color changes and color charts under good lighting Proper collection and storage of urine is necessary to insure preservation of chemical and formed elements

Chemical Exam of Urine Quality Control - use appropriate, commercially prepared positive and negative controls. Use commercially prepared pos and neg controls, at least once per 24 hours, and anytime a new bottle is opened, or question of validity of results. Readings should agree with published results ± one color block.

Chemical Exam of Urine Strip readers Bayer Clinitek automatically reads a urine dipstick and prints out results

Thoughts about urine chemical tests Glucose Presence of glucose (glycosuria) indicates that the blood glucose level has exceeded the renal threshold This test result is useful to screen for diabetes

Thoughts about urine chemical tests Bilirubin Bilirubin is a byproduct of the breakdown of hemoglobin. Not normally found in the urine. Its presence may be an indication of liver disease, bile duct obstruction or hepatitis Bilirubin quickly breaks down in light, resulting in false negative results if the sample is exposed to light for a long period of time.

Thoughts about urine chemical tests Ketones are excreted when the body metabolizes fats incompletely (ketonuria) Ketones evaporate easily and the sample must be kept tightly capped and tested within an hour of collection for best results.

Thoughts about urine chemical tests Specific gravity reflects kidney's ability to concentrate the urine High specific gravity indicates a concentrated sample. The first morning collection specimen usually has a high specific gravity and provides the most useful urinalysis results. Low specific gravity indicates the urine is more ‘water-like’.

Thoughts about urine chemical tests Presence of blood may indicate infection, trauma to the urinary tract or bleeding in the kidneys Positive results are also seen due to contamination with menstrual blood

Thoughts about urine chemical tests pH measures degree of acidity or alkalinity of urine

Thoughts about urine chemical tests Protein Presence of protein (proteinuria) is an important indicator of renal disease False negatives can occur in alkaline or dilute urines or when the primary protein is not albumin.

Thoughts about urine chemical tests Urobilinogen is a degradation product of bilirubin formed by intestinal bacteria. It may be increased in hepatic disease or hemolytic disease

Thoughts about urine chemical tests Nitrite formed by gram negative bacteria converting urinary nitrate to nitrite Any shade of pink color on this pad is considered a positive result.

Thoughts about urine chemical tests Leukocytes (white blood cells) A positive leukocyte usually indicate infection, especially when the nitrite pad is also positive.

Thoughts about urine chemical tests 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