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AUBF LEC > CHEMICAL EXAM Prt. 2 > Flashcards

CHEMICAL EXAM Prt. 2 Flashcards

1
Q

Nonspecific chemical test to differentiate the ff:

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

A

Positive chemical test for blood is nonspecific

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2
Q

BLOOD

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

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

A

5 RBCs/uL

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3
Q

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

A

blood

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4
Q

BLOOD

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

A

(cloudy or smoky red urine)

(clear red urine)

(clear red-brown urine)

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5
Q

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

A

HEMATURIA

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6
Q

• From trauma or damage of renal or genitourinary origin

A

HEMATURIA

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7
Q

BLOOD

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

A

greater than five RBCs per microliter

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8
Q

BLOOD

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

Chemical (Reagent Strip) Test

tetramethylbenzidine

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9
Q

• Differentiation between hematuria and hemoglobinuria requires…

A

both chemical and microscopic analysis.

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10
Q

Major Causes of Hematuria

A

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

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11
Q

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

A

hemoglobinuria

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12
Q

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

A

HEMOGLOBINURIA

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13
Q

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

A

hematuria and hemoglobinuria

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14
Q

________ 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.

A

Hemoglobinuria

haptoglobin

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15
Q

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______

A

haptoglobin

hemosiderin

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16
Q

• Causes of Intravascular hemolysis (HEMOGLOBINURIA)

A

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

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17
Q

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

A

hemosiderin

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18
Q

•______: heme-containing protein found in muscle tissue

A

Myoglobin

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19
Q

• Muscle destruction/rhabdomyolysis

A

MYOGLOBINURIA

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20
Q

_____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.

A

Myoglobin

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21
Q

Major Causes of Myoglobinuria

A

• 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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22
Q

HEMOGLOBINURIA VS.
MYOGLOBINURIA
• Historical test:

A

ammonium sulfate precipitation

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23
Q

ammonium sulfate precipitation

Is used to differentiate…

A

Hemoglobinuria and Myoglobinuria

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24
Q

• 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

A

2.8 g of ammonium sulfate

5 mL centrifuged urine

5 minutes

supernatant

Hemoglobin

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25
Q

Ammonium sulfate precipitation results

• Myoglobin present:

• Hemoglobin present:

A

supernatant remains red, positive for blood

red precipitate, negative for blood

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26
Q

BLOOD

REACTION INTERFERENCE
• False positive

A

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

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27
Q

BLOOD

REACTION INTERFERENCE
• False negative

A

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

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28
Q

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

A

Bilirubin

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29
Q

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

A

yellow

hemoglobin

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30
Q

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

A

BILIRUBIN

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31
Q
  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.

A

spleen and liver

Iron (Fe)

Protein (globin chains)

Protoporphyrin (heme group)

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32
Q
  1. 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.

A

unconjugated (indirect bilirubin)

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33
Q
  1. 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.

A

glucuronyl transferase

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34
Q
  1. 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.

A

gut bacteria

Urobilinogen

Stercobilinogen & Urobilin

35
Q

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).

A

conjugated bilirubin

36
Q

BILIRUBIN

REACTION INTERFERENCE

• False negative

A

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

37
Q

BILIRUBIN

REACTION INTERFERENCE
• False positive

A

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

38
Q

• Confirmatory test for bilirubin

A

ICTOTEST TABLETS

39
Q

ICTOTEST TABLETS

• Can detect ______of bilirubin

A

0.05 to 0.1 mg/dL

40
Q

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

41
Q

ICTOTEST
INTERPRETATION

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

A

purple or blue

42
Q

UROBILINOGEN
• Normally present in urine in concentrations of____

A

1 mg/dL or less

43
Q

UROBILINOGEN

• Best specimen for quantifying and monitoring:

A

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

44
Q

• ‘Alkaline tide’; enhanced urobilinogen excretion in alkaline urine

A

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

45
Q

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

A

UROBILINOGEN

46
Q

UROBILINOGEN

CLINICAL SIGNIFICANCE

A

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

47
Q

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

A

UROBILINOGEN

48
Q

• Nonspecific test for UROBILINOGEN (many reactive substances)

A

Ehrlich’s Raeaction

49
Q

Ehrlich’s Reaction Procedure

A

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

50
Q

CLASSIC EHRLICH’S
REACTION

• Urobilinogen reacts with_________ (Ehrlich’s reagent) in an acid medium to form a______ color

A

p-dimethylaminobenzaldehyde

pink, magenta, or red color

51
Q

• Old qualitative screening for urobilinogen

A

CLASSIC EHRLICH’S
REACTION

52
Q

UROBILINOGEN

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

A

Ehrlich reactive substances

old specimens, formalin preservation

53
Q

UROBILINOGEN

REACTION INTERFERENCE

• Chemstrip
• False positive:
• False negative:

A

highly pigmented urine

old specimens, formalin preservation, high nitrite concentrations

54
Q

Interpretation Example:

• ↑ Urine bilirubin + ↓ Urine urobilinogen =

• ↑ Urine urobilinogen + Normal/↓ Urine bilirubin =

• ↑ Urine bilirubin + ↑ Urine urobilinogen =

A

Biliary obstruction

Hemolytic anemia

Liver disease

55
Q

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

• Sensitivity:______

A

100,000 organisms/mL

56
Q

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

57
Q

• Can be used to evaluate antibiotic therapy

59
Q

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

60
Q

• Valuable in detecting initial bladder infection (cystitis)

• Many UTs start in the bladder and progress upward; may be asymptomatic

61
Q

_______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.

62
Q

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

A

nitrite test

63
Q

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

A

pyelonephritis

64
Q

NITRITE

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

A

nitrate reductase

65
Q

• Rapid screening test for the presence of UTI

65
Q

nitrite reductase

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

A

non-nitrate-reducing bacteria
yeasts
T. vaginalis

66
Q

REACTION INTERFERENCE

• Insufficient contact time between bacteria and nitrate

• At least______
•_____ specimen is ideal

A

4 hours

First morning

67
Q

• Large quantities of bacteria further reducing nitrite to nitrogen

• Antibiotics which inhibit bacterial metabolism

A

REACTION INTERFERENCE

68
Q

REACTION INTERFERENCE

• is commonly found in green vegetables

69
Q

NITRITE

• Lack of urinary nitrate

• Diet is not controlled pre-testing so false-negative results may occur

A

REACTION INTERFERENCE

70
Q

LEUKOCYTE ESTERASE

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

A

10-25 WBCs/microliter

71
Q

• 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

A

Leukocyte esterase

• 20/HPF

72
Q

LEUKOCYTE ESTERASE

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

A

UTI or inflammation in the urinary tract

esterase

73
Q

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

A

LE and nitrite tests

74
Q

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

A

Leukocyturia

bacteriuria

75
Q

LEUKOCYTE ESTERASE

REACTION INTERFERENCE
• False positive

A

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

76
Q

LEUKOCYTE ESTERASE

REACTION INTERFERENCE
••False negative

A

• High concentrations of protein, glucose, oxalic acid, Vitamin C, gentamicin, cephalosporins, tetracyclines

• Inaccurate timing (note: read LE after 2 minutes)

77
Q

SPECIFIC GRAVITY
• Expression of solute concentration

• A fixed SG of_____ regardless of hydration implies significant renal tubular dysfunction

78
Q

SG

• Reagent strip measures______ solutes only

A

ionic or charged solutes only

79
Q

• 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.

A

Urinometry, harmonic oscillation densitometry

80
Q

Indirect SG methods (2)

A

Reagent strip and refractometry

81
Q

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

A

VITAMIN C/ ASCORBIC ACIDI
ASCORBATE

82
Q

VIT C/ ASCORBATE

• can be eliminated by adding____ to the strips.

AUBF LEC (20 decks)

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