Transcript Clinical Laboratory Testing - Urinalysis

Unit #5A – Clinical
Laboratory Testing Urinalysis
Cecile Sanders, M.Ed.,
MLS(ASCP)
Unit #5A – Clinical Laboratory
Testing - Urinalysis
 Urinary
system is
an excretory
system
 Renal System
(reproduced with permission
from Baylor College of Medicine)
Unit #5A – Clinical Laboratory
Testing - Urinalysis
 Collection
and Preservation of Urine
– Urinalysis performed for two purposes
 Check
for metabolic by-products
 Observe physical, chemical and microscopic
characteristics
– Types of Specimens
 First
morning urine specimen is preferred
 Mid-stream (urine caught from middle of urine
stream)
 Clean catch (patient must cleanse urethral
opening prior to urinating and catching urine)
Unit #5A – Clinical Laboratory
Testing - Urinalysis
 Handling
–
–
–
–
and preserving specimens
Examine within 1 hour of collection OR
Refrigerate at 4-6° C for up to 8 hours
Preservatives (least ideal)
When urine sits at room temperature
 Bacteria
multiply
 Glucose decreases
 Casts and cellular elements decompose
Unit #5A – Clinical Laboratory
Testing - Urinalysis
– Color of urine
 Yellow
– dilute urine is usually lighter in color;
concentrated urine is usually dark
 Red – may have blood present
 Brown/black – may be associated with melanoma
 Yellow-brown or green-brown – may be
associated with liver conditions such as
hepatitis or cirrhosis
Unit #5A – Clinical Laboratory
Testing - Urinalysis
 Light
yellow, brown, and dark yellow
urines
Unit #5A – Clinical Laboratory
Testing - Urinalysis
– Transparency
 Urine
normally transparent
 Turbid – may be associated with crystals that
settle out of urine at room or refrigerator
temperature
 Cloudy – may be associated with UTI OR
crystals
Unit #5A – Clinical Laboratory
Testing - Urinalysis
– Specific gravity is the ratio of the weight
of a given volume of the solution (urine) to
the weight of an equal volume of water
 Indicates
concentrations of dissolved chemicals
such as glucose, salts, etc.
 The result of the kidneys’ ability to concentrate
urine
 Normal values – 1.005-1.030 (Ave = 1.015)
 Usually measured by dip stick or refractometer
Unit #5A – Clinical Laboratory
Testing - Urinalysis

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
Unit #5A – Clinical Laboratory
Testing - Urinalysis
 Urine
Multistix – reading dipstick
results manually; colors are matched to
those on the bottle label; timing is
critical for each pad.
Unit #5A – Clinical Laboratory
Testing - Urinalysis
Multistix
Unit #5A – Clinical Laboratory
Testing - Urinalysis
 Bayer
Clinitek automatically reads a
urine dipstick and prints out results
Unit #5A – Clinical Laboratory
Testing - Urinalysis
 Principle
of chemical tests
– pH measures degree of acidity or alkalinity
of urine
– Presence of protein (proteinuria) is an
important indicator of renal disease, such
as pyleonephritis
– Presence of glucose (glycosuria) indicates
that the blood glucose level has exceeded
the renal threshold, such as in diabetes
Unit #5A – Clinical Laboratory
Testing - Urinalysis
– Ketones are excreted when the body metabolizes
fats incompletely (ketonuria), such as in diabetes
– Bilirubin is a byproduct of the breakdown of
hemoglobin. Its presence may be an indication of
liver disease, bile duct obstruction or hepatitis
– Presence of blood may indicate infection, trauma
to the urinary tract or bleeding in the kidneys
– Urobilinogen is a degradation product of bilirubin
formed by intestinal bacteria. It may be increased
in hepatic disease or hemolytic disease
Unit #5A – Clinical Laboratory
Testing - Urinalysis
– Nitrite formed by gram negative bacteria
converting urinary nitrate to nitrite. Presence of
nitrites in fresh urine can indicate infection – in an
old urine, nitrites can be positive without an
infection
– Leukocytes usually indicate infection
– Specific gravity reflects kidney's ability to
concentrate urine

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
Unit #5A – Clinical Laboratory
Testing - Urinalysis
 Resources
– Basic Clinical Laboratory Techniques,
Estridge and Reynolds, Thomson/Delmar
Learning, Fifth Edition, 2008