Transcript URINALYSIS (MLT 305) LECTURE TWO Dr. Essam H. Jiffri 1

URINALYSIS (MLT 305)
LECTURE TWO
Dr. Essam H. Jiffri
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BLOOD
- Blood may be present in the urine either in the
form of intact red blood cells (hematuria) or as
the red blood cell destruction product
hemoglobin (hemoglobinuria).
- Blood present in large quantities can be detected
visually; hematuria produces a cloudy red urine
and hemoglobinuria appears as a clear red
specimen.
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BLOOD
- Any amount of blood greater than 5 cells per
microliter of urine is considered clinically
significant, it is not possible to rely on visual
examination to detect the presence of blood.
- The microscopic examination can be used to
differentiate between hematuria and
hemoglobinuria.
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BLOOD
REAGENT STRIP REACTIONS
- Chemical tests for blood utilize the pseudoperoxidase activity of hemoglobin to
catalyze a reaction between:
- hydrogen peroxide and the chromogen tetramethylbenzidine
to produce an oxidized chromogen, which has a green-blue color.
hemoglobin
H2O2 + Chromogen
Oxidized Chromogen + H2O
peroxidase
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BLOOD
REAGENT STRIP REACTIONS
- Two color charts are provided that correspond to the
reactions that occur with hemoglobinuria and hematuria.
- In the presence of free hemoglobin:
- A strongly positive blue will appear on the pad.
- In contrast, intact red blood cells:
- A speckled pattern will appear on the pad.
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BLOOD
CLINICAL SIGNIFICANCE OF URINE BLOOD
Hematuria
1. Renal calculi
2. Glomerulonephritis
3. Pyelonephritis
4. Tumors
5. Trauma
6. Exposure to toxic chemicals or drugs
7. Strenuous exercise
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BLOOD
CLINICAL SIGNIFICANCE OF URINE BLOOD
Hemoglobinuria
1. Transfusion reactions
2. Hemolytic anemia
3. Severe burns
4. Infections
5. Strenuous exercise
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BLOOD
CLINICAL SIGNIFICANCE OF URINE BLOOD
Myoglobinuria
1. Muscular trauma
2. Prolonged coma
3. Convulsions
4. Muscle-wasting diseases
5. Extensive exertion
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BILIRUBIN
- The appearance of bilirubin in the urine is the first
indication of liver disease and is often detected
long before the development of jaundice.
- Bilirubin provides early detection of hepatitis,
cirrhosis, gallbladder disease, and cancer, and
should be included in every routine urinalysis.
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Bilirubin
Bilirubin, a highly pigmented yellow compound, is a degradation
product of haemoglobin
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Bilirubin
OXIDATION TESTS (FOUCHET’S TEST)
- Urine containing bilirubin usually appears dark yellow or
amber and produces a yellow foam when shaken, this
foam test was actually the first test for bilirubin.
- Oxidation tests utilize the ability of feric chloride dissolved
in trichloracetic acid (Fouchet's reagent) to oxidize
bilirubin to biliverdin, producing a green color.
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Bilirubin
REAGENT STRIP (DIAZO) REACTIONS
- Routine testing for urinary bilirubin by reagent strip
utilizes the diazo reaction, in an acid medium to produce
colors ranging from increasing degrees of tan or pink to
violet, respectively.
- Questionable results should be retested using the
Ictotest which produces a more sharply colored diazo
reaction.
- Colors other than blue or purple appearing on the mat
are considered negative.
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Bilirubin
CLINICAL SIGNIFICANCE OF URINE BILIRUBIN
1. Hepatitis
2. Cirrhosis
3. Biliary obstruction
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Bilirubin
- The presence or absence of bilirubin can be used in
determining the cause of clinical jaundice.
( Urine Bilirubin and Urobilinogen in Jaundice )
Urine Bilirubin
Urine Urobilinogen
Bile duct obstruction
+++
Negative
Liver damage
+ or -
++
Negative
+++
Haemolytic disease
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UROBILINOGEN
- Like bilirubin, urobilinogen is a bile pigment that
results from the degradation of hemoglobin.
- It is produced in the intestine by the oxidation of
bilirubin by the intestinal bacteria.
- Approximately half of the urobilinogen is
reabsorbed from the intestine into the blood,
recirculates to the liver, and is secreted back into
the intestine through the bile duct.
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UROBILINOGEN
- The urobilinogen remaining in the intestine is excreted in
the feces, where it is oxidized to urobilin, the pigment
responsible for the characteristic brown color of the
feces.
- Urobilinogen appears in the urine because, as it
circulates in the blood en route to the liver, it passes
through the kidney and is filtered by the glomerulus.
- A small amount of urobilinogen less than 1 mg/dl or 1
Ehrlich unit is normally found in the urine.
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UROBILINOGEN
EHRLICH'S TUBE TEST
- The reagent used in all tests was
p-dimethylaminobenzaldehyde (Ehrlich's
reagent), addition of Ehrlich's reagent to urine
containing urobilinogen produces a cherry red
color.
- Positive results in dilutions greater than 1 to 20
were considered significant.
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UROBILINOGEN
EHRLICH'S TUBE TEST
- An Ehrlich unit is essentially equal to 1 mg of
urobilinogen.
- Normal values for females are 0.1 to 1.1 Ehrlich
units; and for males, 0.3 to 2.1 Ehrlich units,
these values are based on the recommended 2hour specimen collected after the noon meal
between 2 and 4 PM, which is the time of
greatest urobilinogen excretion.
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UROBILINOGEN
CLINICAL SIGNIFICANCE OF URINE UROBILINOGEN
1. Early detection of liver disease
2. Hemolytic disorders
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NITRITE
- The reagent strip test for nitrite provides a rapid
screening test for the presence of urinary tract
infection.
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NITRITE
REAGENT STRIP REACTIONS
- Nitrite is detected by the Greiss reaction:
- nitrite at an acidic pH reacts with an aromatic
amine to form a diazonium compound that react
with quinolin compound to produce a pink color.
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NITRITE
CLINICAL SIGNIFICANCE OF URNE NITRITE
1. Cystitis (initial bladder infection)
2. Pyelonephritis (an inflammatory process of the
kidney and adjacent renal pelvis)
3. Evaluation of antibiotic therapy
4. Monitoring of patients at high risk for urinary
tract infection
5. Screening of urine culture specimens (detection
of bacteruria)
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SPICIFIC GRAVIIY
- The addition of a specific gravity testing area to
Multistix has eliminated:
 time-consuming step in routine urinalysis
 provided a convenient method for routine
screening.
- It is not recommended to replace osmometry or
refractometry for critical fluid monitoring.
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SPICIFIC GRAVIIY
REAGENT STRIP REACTION
- The test is based on the change in pK(dissociation constant) of poly methyl vinylethermaleic anhydride.
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SPICIFIC GRAVIIY
CLINICAL SIGNIFICANCE OF URINE SPECIFIC CRAVITY
1. Patient hydration and dehydration
2. Loss of renal tubular concentrating ability
3. Diabetes insipidus
4. Determination of unsatisfactory specimens due
to low concentration
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LUKOCYTES
- One of the most frequent findings in the routine
urinalysis is the presence of leukocytes,
indicating a possible infection of the urinary tract.
- Detection of leukocytes was previously made
only by microscopic examination of the urinary
sediment.
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LUKOCYTES
REAGENT STRIP REACTION
-
The chemical reaction is enzymatic, utilizing esterases present in granulocytic
white blood cells to hydrolyze indoxylcarbonic acid ester to produce indoxyl,
which reacts with a diazonium salt to create a purple color.
leukocyte
indoxylcarbonic acid ester
indoxyl + diazonium salt (purple color)
esterases
- It is recommended that trace reactions be repeated on a fresh specimen and that
microscopic examinations be performed on all positive specimens.
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LUKOCYTES
CLINICAL SIGNIFICANCE OF URINE LEUKOCYTES
1. Urinary tract infection
2. Screening of urine culture specimens
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