Physical Examination Of Urine Test 2 Flashcards
Best practic analyze fresh or suitalbey preserved urine, usually refrigerated
1.Examine urine within 30 minutes of the collection, as the changes (decomposition) start
during this time.
2.Examine the urine in the first 1 to 2 hours of collection.
3.Urine is the best culture media for the growth of bacteria.
4.If it is delayed, then refrigerate the urine at 4 °C.
5.Urine left at room temperature >2 hours is not acceptable.
Urine samples to be rejected
1.When urine has incorrect preservatives.
2.When the urine quantity is insufficient.
3.When urine is not transported correctly.
4.When there is a missing or incomplete request form.
5.When urine has no proper identification.
6.When urine shows contamination like stool, etc.
Specimen integrity
Changes in urine composition take place not only in vivo but also in vitro
Test within 2 hours of collection
Refrigerate or chemically preserve if testing is delayed
Most problems are caused by bacterial multiplication
Increased: color, turbidity, pH, nitrite, bacteria, odor
Decreased: glucose, ketones, bilirubin, urobilinogen, RBCs, WBCs, casts
Physical changes in unpreserved urine
Color
color- oxidation or reduction of metabolites
Physical changes in unpreserved urine
Clarity
Decreased- Bacterial growth and precipitation of
amorphous material
Physical changes in unpreserved urine
Odor
Increased- Bacterial multiplication causing breakdown
of urea to ammonia
Physical changes in unpreserved urine
pH
Increased-Breakdown of urea to ammonia by urease-
producing bacteria/loss of CO2
Physical changes in unpreserved urine
Glucose
Decreased- Glycolysis and bacterial use
Macroscopic changes to unpreserved urine
Turbidity
Amorphous crystals may form
causing a pink color. Amorphous
crystals have no clinical significance
Smell - If urine is kept for a long time
at room temperature, it will give an
ammonia smell produced by the
bacteria, which will decompose the
urea in the urine
-erythrin gets deposited on amorphous crystals in a stored
urine specimen causing a pink or “brick dust appearanc
Microscopic changes in Unpreserved urine
Formed elements tend to disintegrate, especially in alkaline urine.
Formed elements are WBCs, RBCs, casts
Is this fluid urine
May be needed in drug screen collections or specimens collected
by needle aspiration
Urine creatinine concentrations 50 times higher than plasma
Urea, sodium (Na), and chloride (Cl) higher in urine than in other
body fluids
Physiologic range is 1.002 to 1.035 for urine specific gravity and
4.0 to 8.0 for pH
Urine from healthy persons contains no protein or glucose,
whereas many other body fluids do
Physical examination of urine includes
Color
Clarity
Specific gravity
Results provide
Preliminary information
Correlation with other chemical and microscopic
results
Physical characteristics
Preliminary information concerning
disorders such as
Glomerular bleeding
Renal tubular function
Liver disease
Inborn errors of metabolism
Urinary tract infection
Color of urine
Normal variations and Abnormal variation causes
- Ranges from colorless to black
- Normal variations caused by
– Normal metabolic functions
– Physical activity
– Ingested materials
– Pathologic conditions - Abnormal variations caused by
– Bleeding
– Liver disease
– Infection
normal urine
- Pale yellow, yellow, dark yellow
- Should be consistent within institution
Urochrome
Urochrome is pigment causing yellow color.
Urochrome is excreted at
darkens upon
- Excreted at a constant rate. More concentrated when
hydration is low resulting in darker urine. - Darkens upon exposure to light
Uroerythin and urobilin
- Uroerythrin and Urobilin are also normal pigments
found in urine. Uroerythrin is most evident when
deposited on amorphous crystals in a stored urine
specimen, causing a pink color or “brick dust” sediment.
Urochrome is pigment causing yellow color.
Dark yellow urine
- may be dehydrated
- may have high conversion of urobilinogen →urobilin
Amber or organe urine
- RBC breakdown in alkaline urine
- may have bilirubin (shake and look at foam)
- Formation of urobilinogen (normal component of urine but
photo oxidizes and turns yellow orange). No yellow foam. - Patient is taking phenazopyridine to relieve symptoms of
urinary tract infection
Pink urine
– oxidized porphobilinogen in patient with
porphyria if specimen has set out too long.
Amorphous crystal formation causes a light pink
color to form
Red urine
RBCs, hemoglobin, beets
Brown or black urine
could be blood or Hgb)
Myoglobin – muscle breakdown. Too much is
damaging to kidney.
oxidized melanogen in patient with malignant
melanoma if specimen has set out too long
Blue/green urine
Biliverdin, Pseudomonas, or propofol
Numerous drugs can change urine color.Numerous drugs can change urine color
Foam
Not normally included on report forms
Normal urine when shaken will produce
white foam that rapidly dissipates
Stable white foam indicates large amounts
of albumin in urine
Yellow foam caused by increased bilirubi
Clarity of urine
- Refers to the transparency or turbidity of a
specimen - Normal reporting
– Clear, hazy, cloudy, turbid - Visual examination
– Gently swirl specimen in a clear container in front of
a good light source - Automated turbidity readings are available
- Fresh clean-catch urine is normally clear
Clarity descriptions
Clear- all solutes are soluble
Visible particles or transparent
abnormal solutes such as glucose, proteins(albumin) or bilirubin are not ruled out
Hazy or slightly cloudy urine
Visible particles are present, and newsprint can read through
Blood cells- RBCs or WBCs present
Cloudy urine
Significant particulate matter, newsprint is blurred or difficult to read
Crystals, epithelial cells, Fats(lipids and Chyle), Microbes bacteria, yeast, trichomonads
Turbid
newspaper cant be seen
Mucus, Mucin, pus, Radiographic contrast media, semen, Spermatozoa, prostatic fluid, Contaminants- feces, powders, talc, creams, and lotions
pathologic turbidity
- Most common: RBCs, WBCs, bacteria
- Turbidity is a good guide to assess possible
pathogenic conditions, but a clear urine doesn’t
necessarily mean normal. Clear can contain
glucose, protein, lysed RBCs and WBCs - A turbid urine may become cloudy if allowed to sit
for too long, especially without refrigeration, due to
formation of nonpathological amorphous crystals.
Color and clarity procedure
Use a well-mixed specimen
View through a clear container
View against a white background
Maintain adequate room lighting
Evaluate a consistent volume of specimen
Determine color and clarity
Odor
- Not routinely reported
- Fresh urine: faintly aromatic
- Older urine: ammonia
- Metabolic disorders: maple syrup urine disease,
ketosis (fruity), infection (ammonia/unpleasant) - Food: garlic, onions, asparagus (genetic: only
certain people can smell asparagus, but all
produce odor) - See Table in text
Aromatic odor
Normal
Foul ammonia-like odor
Bacterial decomposition, urinary tract infectio
Fruity sweet odor
Ketones (diabetes mellitus, starvation, vomitin
Maple syrup odor
Maple syrup urine disease
Mousy odor
Phenylketonuria
Rancid
Tyrosinemia
sweaty feet
Isovaleric acidemia
Cabbage odor
Methionine malabsorption
Bleach odor
Contamination
Specific gravity
Definition
Evaluation of urine concentration
Determines if specimen is concentrated enough to
provide reliable screening results
Definition: the density of a solution compared with
the density of an equal volume of distilled water at
the same temperature
The greater the urine density, the larger the SG.
Measures all solutes (unlike osmolaity).
Isosthenuric
SG of 1.010 (the SG of the plasma
ultrafiltrate)
Hypothenuric and hypersthenuric
Hyposthenuric: SG lower than 1.010
Hypersthenuric: SG higher than 1.010
Normal random specimen range
1.003 to 1.035; most common 1.015 to 1.025
Below 1.003 may not be urine
Consistent low readings: further testing
Refractometer
Definition and how it works
Measures velocity of light in air versus velocity of
light in a solution
Concentration changes the velocity and angle at
which the light passes through the solution
The prism in the refractometer determines the angle
that light passes through the urine and converts
angle to calibrated viewing scale
Methodology of refractometer
Drop of urine placed on prism
Focus on light source, and read
scale
Wipe off prism between
specimens
Calibration
Distilled water should read 1.000;
adjust set screw if necessary
5% NaCl should read 1.022 ± 0.001
9% sucrose should read 1.034 ±
0.001
Refractometer advantages
Temperature compensation not needed
* Light passes through temperature-compensating liquid
* Compensated between 15°C and 38°C
Small specimen size: one or two drops
Disadvantages of Refractometer
Disadvantage: technically requires a correction
when high levels of glucose or protein or radiologic
contrast dyes are present, but this correction rarely
performed by labs.
Reagent strip method
Specific gravity (SG) measured with the reagent strip
method correlates well with gravimetric measurement,
and, unlike the gravimetric or refractometer methods,
does not need to be corrected for glucose or protein.
Cloudy/turbid urines do not need to be clarified before
measuring SG with the reagent strip method.
Alkaline urine can affect the indicator system and lower
the SG result on the reagent pad. If the result is being
read visually, it is recommended that .005 be added to
the SG result when the pH is alkaline. Most dipstick
readers, however, will automatically adjust the SG
reading for pH.
A SG reading higher than the reagent strip range would
need to be measured by another method and may
require dilution.
Reagent strip method impregnated with
when strip is immersed in urine
released
Reagent strip pad impregnated with
polyelectrolyte and pH indicator at an
alkaline pH
When strip immersed in urine, protons
released from polyelectrolyte in proportion
to ionic concentration
Released protons change pH of test pad,
resulting in a color change of pa
Osmolality
- A more representative measure of renal
concentrating ability can be obtained - Specific gravity depends on the number of
particles present in a solution and the density
(size) of these particles - Osmolality is affected only by the number of
particles present
Osmolality normal urine and serum values
Normal urine values 275 to 900 mOsm/kg
Normal serum values 275 to 300 mOsm/kg
Serum remains relatively constant, but
urine value depends on diet, fluid intake,
and physical activity
Osmolality tests
- Osmolality of a solution can be determined by
measuring a property that is mathematically
related to the number of particles in the solution
– Colligative property - Changes in colligative properties
– Lower freezing point
– Higher boiling point
– Increased osmotic pressure
– Lower vapor pressure
What device is used for Osmolality measurements
Measuring osmolality in the urinalysis laboratory
requires an osmometer
Additional step in the routine urinalysis procedure
Automated osmometer utilizes freezing point
depression to measure osmolalit
urine volume
Normal volume 600 to 1800 mL/day
Amount of solutes excreted increases as water
required to excrete them increases
Terminology:
Isothenuria
* Inability of kidneys to change specific gravity of plasma
ultrafiltrate (which is 1.010)
Polyuria
* Excretion of >3 L/day
Oliguria
* Excretion of <400 mL/day
Anuria
* Complete lack of urine excretion
