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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 calculi2. Glomerulonephritis3. Pyelonephritis4. Tumors5. Trauma6. Exposure to toxic chemicals or drugs7. 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 BilirubinUrine Urobilinogen

Bile duct obstruction+++Negative

Liver damage+ or -++

Haemolytic diseaseNegative+++

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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 2-hour 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 infection5.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 vinyl- ethermaleic 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.

leukocyteindoxylcarbonic 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