CHEMICAL EXAM Prt. 2 Flashcards by Kyra Catedral

Nonspecific chemical test to differentiate the ff:

red blood cells (hematuria)
hemoglobin (hemoglobinuria)
myoglobin (myoglobinuria)

Positive chemical test for blood is nonspecific

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BLOOD

• Most accurate method in determining the presence of RBCs in urine

•_____of urine is clinically significant (may not be detected microscopically)

5 RBCs/uL

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A positive reagent strip test for______ may indicate the presence of RBCs, hemoglobin, or myoglobin, each having different clinical implications.

blood

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BLOOD

CLINICAL SIGNIFICANCE (CLARITY AND COLOR OF URINE)
• Hematuria
• Hemoglobinuria
• Myoglobinuria

(cloudy or smoky red urine)

(clear red urine)

(clear red-brown urine)

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• May also be due to post-strenuous exercise and menstrual contamination

HEMATURIA

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• From trauma or damage of renal or genitourinary origin

HEMATURIA

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BLOOD

visual examination is unreliable because blood in amounts________ is already considered clinically significant.

greater than five RBCs per microliter

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BLOOD

•	Uses a reaction with\_\_\_\_\_\_\_ to detect hemoglobin and myoglobin.
•	Provides the ***most accurate way to detect blood in urine.***

Chemical (Reagent Strip) Test

tetramethylbenzidine

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• Differentiation between hematuria and hemoglobinuria requires…

both chemical and microscopic analysis.

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Major Causes of Hematuria

• Renal calculi
• Glomerulonephritis
• Pyelonephritis
• Tumors
• Exposure to chemicals and anticoagulant therapy

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• Intravascular hemolysis
• No RBC in microscopic exam (_______only)

hemoglobinuria

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• Lysis of RBC produced in the urinary tract particularly in dilute, alkaline urine

HEMOGLOBINURIA

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• RBCs in microscopic exam may be seen (______ and ______)

hematuria and hemoglobinuria

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________ occurs when RBCs rupture (hemolysis), releasing free hemoglobin into the bloodstream.

When this exceeds the______ binding capacity, hemoglobin is filtered through the kidneys and appears in urine.

Hemoglobinuria

haptoglobin

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HEMOGLOBIN

• Normally: free hemoglobin forms a complex with_______ (no Hgb in urine)
• If all available ________ is bound, free Hgb is filtered by glomerulus and excreted or processed by renal tubular cells into______

haptoglobin

hemosiderin

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• Causes of Intravascular hemolysis (HEMOGLOBINURIA)

hemolytic anemias
transfusion reactions
severe burns
strenuous exercise
brown recluse spider bites
infections (e. g. malaria)

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When hemoglobin is reabsorbed in renal tubules, it gets stored as_____ (iron-containing granules).

hemosiderin

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•______: heme-containing protein found in muscle tissue

Myoglobin

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• Muscle destruction/rhabdomyolysis

MYOGLOBINURIA

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_____is a heme-containing protein found in muscle tissue.

When muscle cells are damaged, it is released into the blood and filtered by the kidneys, appearing in urine.

Myoglobin

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Major Causes of Myoglobinuria

• Trauma
• Crush injuries and contact sports
• Muscle ischemia (prolonged coma, alcoholism)
• Muscle infections
• Myopathy from medications
• Seizures/convulsions
• Toxins from snake and spider bites

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HEMOGLOBINURIA VS.
MYOGLOBINURIA
• Historical test:

ammonium sulfate precipitation

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ammonium sulfate precipitation

Is used to differentiate…

Hemoglobinuria and Myoglobinuria

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• Historical test: ammonium sulfate precipitation
• _________is added to_______
• Mix and let the specimen sit for_____
• Filter/centrifuge urine and test_____ with reagent strip for blood
•______ is larger and is precipitated

2.8 g of ammonium sulfate

5 mL centrifuged urine

5 minutes

supernatant

Hemoglobin

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Ammonium sulfate precipitation results • Myoglobin present: • Hemoglobin present:

supernatant remains red, positive for blood red precipitate, negative for blood

BLOOD REACTION INTERFERENCE • False positive

• Menstrual contamination • Strong oxidizing reagents • Vegetable peroxidase and bacterial enzymes (e.g., E. coli peroxidase)

BLOOD REACTION INTERFERENCE • False negative

• High SG/crenated RBCs • Unmixed specimens • Formalin as preservative • High concentrations of ascorbic acid > 25 mg/dL

in the urine is an important indicator of liver function and can signal liver disease even before a person shows visible signs of jaundice.

Bilirubin

Bilirubin is a_____ pigment that comes from the breakdown of _____when red blood cells (RBCs) are destroyed after their 120-day lifespan.

yellow hemoglobin

• Provides an early indication of liver disease (only conjugated bilirubin is detected in urine)

BILIRUBIN

1. Breakdown of RBCs in the Reticuloendothelial System (RES) • The____and ____ house phagocytic cells that break down old or damaged RBCs. • Hemoglobin is split into: • ______→ Reused by the body for making new hemoglobin. •______ → Broken down into amino acids for reuse. • _____→ Converted into bilirubin.

spleen and liver Iron (Fe) Protein (globin chains) Protoporphyrin (heme group)

2. Transport in the Blood • Bilirubin, in this stage, is______, meaning: • It cannot ***dissolve in water.*** • It ***binds to albumin*** for transport in the blood. • It ***cannot be excreted by the kidneys.***

unconjugated (indirect bilirubin)

3. Processing in the Liver • Unconjugated bilirubin enters the liver cells. • Inside the liver, the enzyme_____ attaches glucuronic acid to bilirubin, making it conjugated bilirubin (direct bilirubin). • Conjugated bilirubin is water-soluble, so: • It does not need albumin to move. • It is excreted in bile into the intestines.

glucuronyl transferase

4. Breakdown in the Intestine • In the intestines, _____transform conjugated bilirubin into: •______ → Some is reabsorbed into the blood and excreted in urine. • ______ and _____→ Give feces its characteristic brown color.

gut bacteria Urobilinogen Stercobilinogen & Urobilin

Clinical Significance of Bilirubin in Urine Normally, ________is not found in urine because it is fully excreted into bile. However, certain conditions disrupt normal metabolism, leading to bilirubinuria (presence of bilirubin in urine).

conjugated bilirubin

BILIRUBIN REACTION INTERFERENCE • False negative

• Exposure to light • Ascorbic acid > 25 mg/dL • High nitrite concentrations

BILIRUBIN REACTION INTERFERENCE • False positive

• Highly-pigmented urine (e.g., phenazopyridine) • Indican (intestinal disorders)

• Confirmatory test for bilirubin

ICTOTEST TABLETS

ICTOTEST TABLETS • Can detect ______of bilirubin

0.05 to 0.1 mg/dL

ICTOTEST TABLETS • Reagent strip:_____ lower limit of detection • Add 10 drops of urine to an absorbent test mat • Place 1 Ictotest tablet to the moistened area • Add 2 drops of water to the tablet • After 30 seconds, the tablet is removed, and the absorbent pad is observed for the development of any purple or blue coloration, which indicates a positive test

0.5 mg/dL

ICTOTEST INTERPRETATION the absorbent pad is observed for the development of any_______ coloration, which indicates a positive test

purple or blue

UROBILINOGEN • Normally present in urine in concentrations of____

1 mg/dL or less

UROBILINOGEN • Best specimen for quantifying and monitoring:

2 hours after mid-day meal (2-4 PM)

• 'Alkaline tide'; enhanced urobilinogen excretion in alkaline urine

2 hours after mid-day meal (2- 4 PM)

• Labile in acid urine and easily photo-oxidizes into urobilin

UROBILINOGEN

UROBILINOGEN CLINICAL SIGNIFICANCE

• Early detection of liver disease • Liver disorders, hepatitis, cirrhosis, carcinoma (hepatic) • Hemolytic disorders (pre-hepatic)

CLINICAL SIGNIFICANCE • Early detection of liver disease • Liver disorders, hepatitis, cirrhosis, carcinoma (hepatic) • Hemolytic disorders (pre-hepatic)

UROBILINOGEN

• Nonspecific test for UROBILINOGEN (many reactive substances)

Ehrlich’s Raeaction

Ehrlich’s Reaction Procedure

• 1 part Ehrlich's reagent + 10 parts urine in a tube and incubate for 5 minutes

CLASSIC EHRLICH'S REACTION • Urobilinogen reacts with_________ (Ehrlich's reagent) in an acid medium to form a______ color

p-dimethylaminobenzaldehyde pink, magenta, or red color

• Old qualitative screening for urobilinogen

CLASSIC EHRLICH'S REACTION

UROBILINOGEN REACTION INTERFERENCE • Multistix • False positive: • False negative:

Ehrlich reactive substances old specimens, formalin preservation

UROBILINOGEN REACTION INTERFERENCE • Chemstrip • False positive: • False negative:

highly pigmented urine old specimens, formalin preservation, high nitrite concentrations

Interpretation Example: • ↑ Urine bilirubin + ↓ Urine urobilinogen = • ↑ Urine urobilinogen + Normal/↓ Urine bilirubin = • ↑ Urine bilirubin + ↑ Urine urobilinogen =

Biliary obstruction Hemolytic anemia Liver disease

• Based on the ability of certain bacteria to reduce nitrate (normal constituent) to nitrite • Sensitivity:______

100,000 organisms/mL

• Can be used as ***periodical screen in persons at high risk for UTI***

NITRITE

• Can be used to evaluate antibiotic therapy

NITRITE

• Early detection of bacteriuria plus antibiotic therapy can prevent pyelonephritis and other complications

NITRITE

• Valuable in detecting initial bladder infection (cystitis) • Many UTs start in the bladder and progress upward; may be asymptomatic

NITRITE

_______is an infection of the bladder, usually caused by bacteria entering the urethra from external contamination. • The short urethra in women makes UTIs eight times more common in females than in males. • Catheterized patients are also at a higher risk due to bacterial colonization in the bladder.

Cystitis

The_____ test helps detect early bladder infections, even when the patient is asymptomatic or has mild, vague symptoms.

nitrite test

If cystitis is left untreated, the infection can travel up the ureters to the kidneys, causing______.

pyelonephritis

NITRITE REACTION INTERFERENCE • Bacteria that lack______ • It is found in many ***Gram-negative bacteria*** that most frequently cause UTI

nitrate reductase

• Rapid screening test for the presence of UTI

NITRITE

nitrite reductase • Other organisms (3) that cause UTI are not detected

non-nitrate-reducing bacteria yeasts T. vaginalis

REACTION INTERFERENCE • Insufficient contact time between bacteria and nitrate • At least______ •_____ specimen is ideal

4 hours First morning

• Large quantities of bacteria further reducing nitrite to nitrogen • Antibiotics which inhibit bacterial metabolism

REACTION INTERFERENCE

REACTION INTERFERENCE • is commonly found in green vegetables

NITRITE

NITRITE • Lack of urinary nitrate • Diet is not controlled pre-testing so false-negative results may occur

REACTION INTERFERENCE

LEUKOCYTE ESTERASE • Sensitivity:______ • Note: A negative result does not rule out increased number of WBCs

10-25 WBCs/microliter

• Normally, WBCs may be present in urine in small numbers _______ indicate a pathologic process • A more standardized test than microscopic examination of urine sediment • Can detect lysed WBCs which are not seen in microscopic examination

Leukocyte esterase • 20/HPF

LEUKOCYTE ESTERASE CLINICAL SIGNIFICANCE • Increased WBCs are indicators of_____ or _____ • Detects the presence of_____ in granulocytes and monocytes (also present in Trichomonas and histiocytes)

UTI or inflammation in the urinary tract esterase

• Assessment of _____ and____can be cost-effective measures to determine the necessity of performing urine culture

LE and nitrite tests

• Infections caused by Trichomonas, Chlamydia, yeast, and inflammation of renal tissue produce_____ without_____

Leukocyturia bacteriuria

LEUKOCYTE ESTERASE REACTION INTERFERENCE • False positive

• Vaginal secretions contamination • Strong oxidizing agents or formalin in the container • Highly -pigmented urine

LEUKOCYTE ESTERASE REACTION INTERFERENCE ••False negative

• High concentrations of protein, glucose, oxalic acid, Vitamin C, gentamicin, cephalosporins, tetracyclines • Inaccurate timing (note: read LE after 2 minutes)

SPECIFIC GRAVITY • Expression of solute concentration • A fixed SG of_____ regardless of hydration implies significant renal tubular dysfunction

1.010

SG • Reagent strip measures______ solutes only

ionic or charged solutes only

• ***Direct specific gravity methods*** determine the actual or true density of urine, regardless of the solutes present. All solutes are detected and measured • Examples: (2) • Other solutes are present because of other abnormal processes unrelated to concentrating ability.

Urinometry, harmonic oscillation densitometry

Indirect SG methods (2)

Reagent strip and refractometry

• Has reducing properties which inhibits reaction of blood, bilirubin, glucose, leukocyte esterase and nitrite.

VITAMIN C/ ASCORBIC ACIDI ASCORBATE

VIT C/ ASCORBATE • can be eliminated by adding____ to the strips.

iodate

CHEMICAL EXAM Prt. 2 Flashcards

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