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Urinalysis and Body Fluids 4214 > Test 3: Chemical Examination of Urine > Flashcards

Test 3: Chemical Examination of Urine Flashcards

1
Q

Reagent strips are a color what

A

producing chemical reaction takes place when
the absorbent pad containing the reagent(s) contacts
urine

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2
Q

what are the two types of reagent strips

A
  • Single and multitest strips available
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3
Q

Reagent strips provide a

A

simple, rapid means for
performing routine chemical tests on urine

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4
Q

The brand and number of tests of reagent strips are

A

matter of
laboratory preference; Specified by urinalysis

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5
Q

Reagent strips

The reactions are interpreted as blank

Several degrees of what are shown

and range of readings

what is the value reordered in

A

 The reactions are interpreted by
comparing the color produced on the pad
within the required time frame with a chart
supplied by the manufacturer
 Several degrees of color are shown to
provide semiquantitative readings of neg,
trace, 1+, 2+, 3+, and 4+
 Estimates of mg/dL are also provided for
many of the test areas

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6
Q

Reagent strip technique

A

 Dip strip briefly into well-mixed specimen at room temperature
 Remove excess urine by touching edge of strip to container as strip is
withdrawn
 Blot edge of strip on absorbent pad
 Wait specified amount of time
 Read using a good light source

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7
Q

Improper techniques errors

Formed elements such as

Allowing the strip to remain blank

Excess urine remaining blank

A
  • Formed elements such as red and white
    blood cells sink to the bottom of the
    specimen and will be undetected in an
    unmixed specimen
  • Allowing the strip to remain in the urine for
    an extended period may cause leaching of
    reagents from the pads
  • Excess urine remaining on the strip after
    its removal from the specimen can produce
    a runover between chemicals on adjacent
    pads, producing distortion of the colors
    shake
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8
Q

Improper technique

The timing for reactions to blank

A good what is required

blank charts are different

Specimens must be returned to blank

A
  • The timing for reactions to take place
    varies between tests and manufacturers;
    the manufacturer’s stated time should be
    followed
  • A good light source is essential for
    accurate interpretation of color reactions
  • Color charts from different
    manufacturers are not interchangeable
  • Specimens that have been refrigerated
    must be allowed to return to room
    temperature prior to reagent strip testing
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9
Q

Handling and storing reagent strips

A

 Store with desiccant in an opaque, tightly sealed container
 Remove strips from container immediately prior to use
 Store below 30°C
 Do not use past the expiration date
 Visually inspect for discoloration/deterioration

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10
Q

Quality control of reagent strips

Run positive and negative controls how often

Run additional controls when

A

 Run positive and negative controls at least once per
24 hours
 Run additional controls
 When a new lot of strips is opened
 When results are questionable
 When there are concerns over strip integrity

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11
Q

record control results

Do not use what

A

 Manufactured positive and negative controls are
available
 Do not use distilled water as a negative control as
reactions are designed for urine ionic concentration
8

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12
Q

Specific gravity

A

 The strip measures the ionic concentration of the sample, which relates to the specific gravity. It is
not perfect, but it is what is used for routine analysis.
 The reagent pad contains polyelectrolytes with acid groups that get dissociated to a degree
dependent on the ionic strength (how many ions) of the sample.
 The reagent pad contains a pH indicator (bromothymol blue) which then measures the change in
pH. When urine has increased specific gravity, the reagent pad becomes more acidic. The colors
of the reagent pad will range from deep blue-green in urines of low ionic concentration through
green and yellow-green in urines of increasing ionic concentration. The color blocks are in
increments of 0.005 for specific gravity readings between 1.000 and 1.030. Figure 7-8 shows the
correlation between specific gravity ranges and color changes on the reagent strip pad. An
illustration shows the color chart for specific gravity at 45 seconds

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13
Q

Read SG at

A

45 seconds

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14
Q

Urine pH

what systems are buffers

A

 Renal system, pulmonary system and blood buffers maintain a pH that is
compatible with life

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15
Q

Urine pH

Slightly acidic urine at

A

5.0-6.0

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16
Q

Postprandial specimens are more

A

Alkaline

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17
Q

Not physiologically possible pH

A

 pH greater than 8 and less than 4.4 physiologically
impossible

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18
Q

pH reagent strip reactions

indicators

A

 Double-indicator system reaction
Methyl red = 4 to 6 red/orange to yellow
Bromthymol blue = 6 to 9 green to blue
Methyl red + H+ → Bromthymol blue − H+
(Red/Orange → Yellow) (Green → Blue)

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19
Q

what are other things used besides pH reagent strips?

Interferences for pH methods

A

 Can also use a pH meter or pH paper
 Interference
– No known substances interfere with urinary pH measurements performed by
reagent strips

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20
Q

pH of 4.5-6.9

A

Diet and Sleep
Metabolic acidosis (diabetic acidosis)
Respiratory acidosis
Urinary disorders: Renal Failure, Uremia

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21
Q

pH of 7.0-7.9

A

Diet
Metabolic alkalosis
Respiratory alkalosis
Urinary disorders: UTI, Renal tubular acidosis
Medications

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22
Q

Blood

Hematuria

Hemoglobinuria

A

 Hematuria: intact RBCs
-Cloudy red urine
 Hemoglobinuria: product of RBC destruction
-Clear red urine

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23
Q

Blood

Any amount of blood greater then

Chemical test for blank

The microscopic exam can be used to

A

 Any amount of blood greater than five cells per microliter of urine is
considered clinically significant
 Chemical tests for hemoglobin provide the most accurate means for
determining the presence of blood
 The microscopic examination can be used to differentiate between
hematuria and hemoglobinuria

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24
Q

Hematuria diseases

A

Glomerular disease
Pyelonephritis or cystitis
Renal calculi
Tumors
Also trauma, hypertension, exercise, smoking, meds and other toxins

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25
Q

Hemoglobinuria

A

Intravascular hemolysis: transfusion reactions, hemolytic anemia,
paroxysmal nocturnal hemoglobinuria
Infections: malaria
Chemical toxicity: copper, nitrates, nitrites
Exertional hemolysis

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26
Q

Myoglobiuria

A

Muscles: trauma, ischemia, infections, medications
Seizures
Toxins: spiders and snakes

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27
Q

Hematuria vs hemoglobinuria

A

Rapid test to distinguish hematuria from hemoglobinuria. The onset of red urine during or
shortly after a blood transfusion may represent hemoglobinuria (indicating an acute
hemolytic reaction) or hematuria (indicating bleeding in the lower urinary tract).

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28
Q

Differentiation of Hemoglobinuria and Myoglobinuria

Both have what positive

If correlation of chemical and microscopic results do not indicate

Difficult to distinguish but

A

 Both heme proteins and toxic to kidneys.
 Both will give a positive blood on dipstick
 If correlation of chemical and microscopic results do not indicate hematuria, further
studies are needed to distinguish hemoglobinuria from myoglobinuria
 Difficult to distinguish but necessary for diagnosis and treatment

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29
Q

Myoglobin in urine produces a

A

Myoglobin in urine produces a brown urine. Can spin down urine. Then can look at
plasma to diff. myoglobinuria from hemoglobinuria.

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30
Q

Hemoglobin produces a

A

Hemoglobin produces a reddish coloration in the spun serum, whereas myoglobin does not
discolor the serum (remains clear)

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31
Q

Hematuria produces a

Hemoglobinuria produces a

Myoglobinuria produces a

A

URINE
Hematuria produces a reddish sediment in spun urine samples.
Hemoglobinuria produces red to brown color in centrifuged specimen.
Myoglobinuria is brown, and often only a few RBCs are present in the urine

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32
Q

Plasma hemoglobin produces a

A

Hemoglobin produces a reddish or brown coloration in the spun serum, whereas
myoglobin does not discolor the serum

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33
Q

CK levels are markedly what of what

A

K levels are markedly elevated in myoglobinuria. Results of radioimmunoassays for the
specific measurement of serum or urine myoglobin can be delayed by several days and
are not useful in immediate diagnosis and treatment.

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34
Q

Blood reagent strip reactions of hemoglobin

Principle

Strip pad contains what

gets oxidized by

A

 Principle pseudo peroxidase activity of hemoglobin

 Strip pad contains the chromogen tetramethylbenzidine
 Gets oxidized by Hgb or Myoglobin and produces a green-blue color.

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35
Q

Pseudoperoxidase activity reaction

A

H202 + Chromogen with enzymes Hb and MB —–> Oxidized chromogen + H20

  • Tetramethylbenzidine. Hb, Hemoglobin, Mb, myoglobin
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36
Q

Blood reagent strip

Two charts corresponding to

Free heme shows

Intact RBCs show

Report and sensitivity

A

 Two charts corresponding to different reactions
 Free hemoglobin shows uniform color
 Intact RBCs show a speckled pattern on pad
 Report: trace, small (1+), moderate (2+), large (3+)
 Sensitivity 5 RBCs/μL

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37
Q

False positives of

A

False positives can occur if menstrual blood present, certain bacteria or high level of Vitamin C

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38
Q

Leukocyte esterase (LE)

A Few of what are blank

Advantages

usually see what

Not considered what

A

 A few WBCs are normal; anything over 20 WBCs/mL indicates pathologic
process: inflammation/response to infection.
 Advantage: detects presence of lysed leukocytes.
 Usually see bacteria, but could also be in infection with organisms other
than bacteria which may not be readily apparent microscopically
(Chlamydia)
 Not considered a quantitative test: do microscopic if positive

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39
Q

LE detects what

A

LE test detects the presence of leukocyte
esterase in the granulocytes and monocytes

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40
Q

LE is catalyzed by

A
  • LE catalyzes the hydrolysis of acid ester on the pad
    to aromatic compound (indoxyl or pyrrole)
    and acid; aromatic compound reacts with
    diazonium salt on a pad for purple color
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41
Q

LE reaction have to wait

A
  • Note you have to wait 2 minutes.
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42
Q

LE false positive

A

 Presence of vaginal contamination
 Highly pigmented urine (nitrofurantoin, beets)

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43
Q

False negatives of LE

A

 High concentrations of protein, glucose, high specific gravity
 Presence of the antibiotics; gentamicin, cephalosporins, tetracyclines or other
strong oxidizers

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44
Q

what will not be detected in LE

A

Detects LE so lymphocytes are not detected because they
don’t produce the enzyme.

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45
Q

Nitrate

A

Tests ability of bacteria to reduce nitrate
(normal constituent) to nitrite (abnormal)
Correspond with a quantitative bacterial
culture criterion of 100,000 organisms/mL
Does not negate the need for culture.
24

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46
Q

Nitrite reagent strip reaction step one

A

Step one picture

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47
Q

Nitrite reagent strip reaction step two

A

para-arsanilic acid or sulfanilamide in step one

diazonium salt + tetrahydrobenzoquin—→ pink azodye

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48
Q

Nitrite reaction false positives

A

Old specimens (bacterial multiplication)
Highly pigmented urine (phenazopyridine or beets)

49
Q

Nitrite reactions false negatives

A

Large quantities of bacteria converting nitrite to nitrogen
High concentrations of ascorbic acid

50
Q

Protein indicates

A

Most indicative of renal disease

51
Q

proteinuria seen

A

Proteinuria seen in early renal disease

52
Q

Normal protein range

A

Normal = <20 mg/dL

53
Q

Low molecular weight proteins are blanked

A

Low-molecular-weight serum proteins are filtered; many are reabsorbed

54
Q

what is the primary protein of concern

A

Albumin is primary protein of concern

55
Q

Other proteins include

A

Vaginal, prostatic, and seminal proteins
Tamm-Horsfall (uromodulin), secretory IgA

56
Q

Proteinuria results from

A

(1) an increase in the quantity of plasma proteins that are filtered, or
(2) filtering of the normal quantity of proteins but with a reduction in the reabsorptive ability of the renal tub

57
Q

Pre-renal overflow

A

Excessive production of low-molecular weight proteins following hemolytic event or sepsis or myoglobins from trauma (rhabdomyolysis). Goes away when condition resolved. Light chain deposition disease/multiple myeloma and amyloidosis produce light chain proteins that pass into urine. The light chains from myeloma are called Bence Jones proteins.

58
Q

Renal glomerular proteinuria

A

In disorders that cause glomerular damage. Most common and most serious. This is seen in nephrotic syndrome. Also in chronic glomerulonephritis and sclerotic conditions (focal segmented, diabetic nephropathy, lupus). Very high protein seen in urine.

59
Q

Renal tubular proteinuria

A

When tubular function is impaired (Fanconi’s, pyelonephritis, interstitial nephritis and systemic diseases like lupus. Lower protein levels - <2.5 mg/day.

60
Q

Post-renal proteinuria

A

Inflammation anywhere in the urinary tract or from injury, tumors or hemorrhage that allows blood proteins into the urinary tract. Usually goes away if condition is resolved.

61
Q

Postural proteinuria

A

considered to be a functional proteinuria. Protein in urine only when patient is in an upright (orthostatic) position. considered to be benign, but persistent proteinuria may develop Protein <1.5 g/day. Monitored every 6 months.

62
Q

Contamination

A

Dehydration, low blood pressure, inflammation, aspirin, exercise
Vaginal and prostrate secretions

63
Q

Proteins error of indicators

A

Certain indicators change color in the presence of protein at a constant pH on the pad is maintained at 3.0 by buffers.
Protein accepts H+ from the indicator, increased sensitivity to albumin due to more amino groups to accept H+ than other proteins

64
Q

pH of 3.0

A

Indicator (H+) + Protein (albumin) → H+ ions released from indicator
(Yellow) reactant (Green/Blue)

65
Q

Protein indicators

A

Indicator may be sulfanapthalein or tetrabromphenol blue

66
Q

report proteins as

trace protein values

A

Report: neg, trace, 1+, 2+, 3+, 4+, or 30, 100, 300, 2000 mg/dL

Trace values are <30 mg/dL

67
Q

Protein interferes and limitation

A

Fortunately, the test is designed to be very sensitive to the presence of albumin, but this means globulins, myoglobulin and immunoglobulin light chains (Bence Jones Proteins) are not detected by the strips because they are usually in too low a concentration to be detected.

If urine is very alkaline – can overwhelm the buffering action on the pad and give a false positive

68
Q

Sulfosalicylic Acid (SSA) Precipitation

A

Confirmatory test for protein

Proteins are precipitated by 5-sulphosalicylic acid.
Any resulting turbidity will give an estimation of the amount of protein present in the urine which can be subjectively quantitated visually or more precisely quantitated using photometry.
Cells and casts in the urine must be removed by centrifuging before carrying out the test.
The test can detect albumin, hemoglobin, myoglobin, and Bence Jones proteins.

69
Q

Sulfosalicylic Acid (SSA) Precipitation

results

A

Negative : No cloudiness
Trace: Faint turbidity.
1+ : definite turbidity
2+ : Heavy turbidity but no flocculation
3+ : Heavy turbidity with light flocculation.
4+ : Heavy turbidity with heavy flocculation.

70
Q

Microalbuminuria

A

-Diabetic nephropathy with type 1 and type 2 diabetes mellitus
-Reduced glomerular filtration
-Eventual renal failure
Since the levels are low, labs use specific strips to detect.

71
Q

Albumin creatine ratio

A

ACR = Albumin/Creatinine
ACR = 8/0.11 = 72.7 mg/g
The table in the paragraph above shows that a result between 30 and 300 mg/g
means the level of albuminuria is moderately increased,
and the patient places in category A2 of CKD stages.

72
Q

Urine albumin

A

Albumin in urine: 8 mg/dL

73
Q

Creatinine in urine

A

Creatinine: 110 mg/dL = 0.11 g/dL

74
Q

further testing of proteins

A

Once the presence of an increased amount of urine
protein has been established, accurate methods are avail-
able to differentiate and quantify the proteins. Electro-
phoresis, nephelometry, turbidimetry, and radial
immunodiffusion methods are used and are discussed at
length in clinical chemistry textbooks.

75
Q

Glucose

Clinical significance

Normally, all glucose passes through

A

Clinical Significance. The presence of glucose in the urine is termed glycosuria (or glycosuria).

Normally, all glucose that passes through the glomerular filtration barrier into the ultrafiltrate is actively reabsorbed by the proximal renal tubules.

76
Q

However, tubular reabsorption of glucose

A

is a threshold-limited process with a maximum reabsorptive capacity (Tm) averaging about 350 mg/min

77
Q

When the level of glucose in the blood exceeds

A

When the level of glucose in the blood exceeds its renal threshold level of approximately 160 to 180 mg/dL, the ultrafiltrate concentration of glucose exceeds the reabsorptive ability of the tubules, and glucosuria occurs: NORMAL RENAL THRESSHOLD FOR GLUCOSE = 160 to 180 mg/dL

78
Q

Glucosuria is caused by

A

(1) a prerenal condition (hyperglycemia), or
(2) a renal condition (defective tubular absorption).
(1) Gestational diabetes is a type of diabetes that happens during pregnancy. Your body
needs a lot of energy as your baby grows, but sometimes it can’t keep up with demand
and doesn’t make enough insulin.
(2) Renal glycosuria is a rare inherited condition where your body eliminates sugar in your
urine even though your blood levels are normal. In this condition, you don’t have too much
glucose but your body gets rid of it anyway.
(3) Fanconi syndrome is a general term for a defect in your kidneys that causes problems
absorbing glucose

79
Q

Gestational diabetes

A

is a type of diabetes that happens during pregnancy. Your body
needs a lot of energy as your baby grows, but sometimes it can’t keep up with the demand
and doesn’t make enough insulin

80
Q

Renal glycosuria

A

Renal glycosuria is a rare inherited condition where your body eliminates sugar in your
urine even though your blood levels are normal. In this condition, you don’t have too much
glucose but your body gets rid of it anyway

81
Q

Fanconi syndrome

A

Fanconi syndrome is a general term for a defect in your kidneys that causes problems
absorbing glucose

82
Q

Glucose reagent strip reaction

A

1.) Glucose + O2 with enzyme Glucose oxidase ———> Gluconic acid + H2O2

2.) H202 + chromogen with enzyme peroxidase ——> Oxidized chromogen + H20

83
Q

Dipstick interferences of glucose

False positive and negatives

A

 False-positive: only if contaminated with peroxide, oxidizing detergents
(unlikely)
 False-negative: enzymatic reaction interference
 High levels of ascorbic acid
 High levels of ketones (unlikely)
 High specific gravity and low temperature
 Greatest source of error is old specimens
 Subjecting the glucose to bacterial degradation
42

84
Q

Copper reduction test Clllinitest

and reaction

A

The dipstick used in urine testing will only detect glucose. Clinitest
tablets will detect other sugars such as lactose, fructose, galactose,
and pentoses. These other sugars may signify metabolic disorders
when found in urine of small children.
CuSO4 (cupric sulfide) + reducing substance –Heat—>
Cu2O (cuprous oxide) + oxidized substance → color Alkali
(blue/green to orange/red)
43

85
Q

Clllinitest reaction

A

CuSO4 (cupric sulfide) + reducing substance –Heat—>
Cu2O (cuprous oxide) + oxidized substance → color Alkali
(blue/green to orange/red)

86
Q

Ketones

A

 Ketones are formed during the catabolism of fatty acids.
 Three intermediate products of fat metabolism
 Acetone: 2%
 Acetoacetic acid: 20%
 β-hydroxybutyrate: 78%
 Appear in urine when body stores of fat must be metabolized to supply
energy (carbs not available or can’t be used)
 May signify diabetic ketoacidosis
45

87
Q

Three intermediate products of fat metabolism

A

 Acetone: 2%
 Acetoacetic acid: 20%
 β-hydroxybutyrate: 78%

88
Q

Ketones appear when

Signify what

A

 Appear in urine when body stores of fat must be metabolized to supply
energy (carbs not available or can’t be used)

89
Q

Ketone test

A

 Primary reagent: sodium nitroprusside
 (Nitroferricyanide)
 Measure primarily acetoacetic acid
 Assumes the presence of β-hydroxybutyrate and acetone
 Acetoacetic acid (alkaline) + nitroprusside → purple color

90
Q

Ketone reaction interferences

A

 Levodopa in large dosage
 Medications containing sulfhydryl groups (cancer, hypertension)
 May produce atypical color reactions
 False-positive results from improperly timed readings
 Falsely decreased values in improperly preserved specimens
 Breakdown of acetoacetic acid by bacteria
 Ketones are volatile and may evaporate if specimen left open.

91
Q

Acetest for ketones

A

 Not a urine confirmatory test
 Tablet = sodium nitroprusside, glycine,
disodium phosphate, lactose (gives
better color)
 Can use as a backup or to evaluate
questionable results, but affected by
same interferences seen on dipstick.
48

92
Q

Bilirubin

A

 Urine bilirubin early indicator of liver disease
 Normal degradation product of hemoglobin
 RBCs destroyed by liver and spleen following 120-day life span
 Body recycles iron, protein
 Protoporphyrin is broken down into bilirubin
 Bilirubin is bound to albumin
 Kidneys cannot excrete
 Unconjugated bilirubin: water insoluble

93
Q

Bilirubin is a normal degradation product of what

A

 Normal degradation product of hemoglobin
 RBCs destroyed by liver and spleen following 120-day life span

94
Q

Unconjugated bilirubin is water what

A

 Unconjugated bilirubin: water insoluble

95
Q

Unconjugated BR and albumins

A

Can’t get through the glomerulus

96
Q

Conjugated BR can pass

A

through glomerulus

97
Q

Clinical significance of bilirubin

Conjugated bilirubin appears

A

 Conjugated bilirubin appears in urine with bile duct
obstruction, liver disease or damage

98
Q

Clinical significance of bilirubin

Obstruction

A

 Obstruction: bilirubin backs up into circulation and is excreted
in urine
 No urobilinogen is formed

99
Q

Hepatitis, cirrhosis:

A

conjugated bilirubin leaks back into
circulation from damaged liver; some bilirubin passes to
intestine

100
Q

Hemolytic disease

A

increased unconjugated bilirubin,
increased urobilinogen

101
Q

Hemolytic disorders (hemolytic
anemia, sickle cell, transfusion
reactions)

Mechinism

A

Liver function normal. Overproduction of bilirubin from heme. Is
unconjugated and bound to albumin (does not pass through
glomerulus but passes through liver to intestine). In intestine,
some of the excess urobilinogen is reabsorbed and shows up in
urine.

102
Q

Liver disease

A

Liver can’t perform normal bilirubin metabolism. Conjugated
bilirubin leaks into circulation and can pass through glomerulus.
Less urobilinogen is removed from circulation by diseased liver,
more goes to kidney

103
Q

Bile duct obstructions

A

Liver function normal. Conjugated bilirubin can’t pass through
liver so overflows into circulation. Since no bilirubin is going to
intestines, no urobilinogen is formed. (results in pale stools).

104
Q

Bilirubin strip reactions

A

The principle is a diazo reaction

bilirubin glucuronide + *diazonium salt——–> azodye
(tan or pink to violet)

diazonium salt- (2,4-dichloroaniline diazonium salt or 2,6-dichlorobenzene
-diazonium-tetrafluoroborate

105
Q

Ictotest-diazo tablets

A

 Confirmatory for bilirubin
 Tablets containing p-nitrobenzene-diazonium-p-toluenesulfonate, SSA, sodium carbonate, and boric acid
 Use the specified mat for the test; mat keeps bilirubin on the surface for reaction, Interfering substances are
washed into the mat, and only bilirubin remains on the surface
 The same principle as strip but picks up lower levels
 Positive reaction = blue-to-purple color

106
Q

FALSE positives of bilirubin

A

 Urine pigments
 Pyridium (phenazopyridine)
 Drugs indican, iodine

107
Q

False negatives of bilirubin

A

 Old specimens - bilirubin photo oxidized and is otherwise unstable, especially
at room temp
 Ascorbic acid >25 mg/dL
 Nitrite
 Combine with diazonium salt and block bilirubin reaction

108
Q

Urobilinogen strip reactions

A

urobilinogen ERC + p-dimethylaminobenzaldehyde (Ehrlich’s reagent) ——→ red color
CHEMSTRIP:
Acid
urobilinogen + diazonium salt —→ red azodye

109
Q

Urobilinogen reaction interferences

A

 Ehrlich reactive compounds: porphobilinogen, indican, sulfonamides,
methyldopa, procaine, chlorpromazine, p-aminosalicylic acid
 Chemstrip: false-negative with high nitrite interferes with diazo reaction.
Colored urine from drugs or beets can mask reaction.
 Both tests: urobilinogen is highest after meals (increased bile salts), old
specimens and formalin preservation decrease results
 NOTE: These tests cannot reliably indicate a decrease or absence of
urine urobilinogen. Have to interpret using fecal and blood analysis. No
confirmatory test available.
 Urobilinogen is very unstable in acid urine (so best to test after meal when
urine is more alkaline) and easily photo oxidizes to urobilin.
58

110
Q

Ehrlich reactive compounds

A

porphobilinogen, indican, sulfonamides,
methyldopa, procaine, chlorpromazine, p-aminosalicylic acid

111
Q

Chemstrip for urobilinogen reaction interferences

A

false-negative with high nitrite interferes with diazo reaction.
Colored urine from drugs or beets can mask reaction.

112
Q

Urobilinogen is high after what so

A

Both tests: urobilinogen is highest after meals (increased bile salts), old
specimens and formalin preservation decrease results

113
Q

Note for urobilinogen test

A

these tests cannot reliably indicate a decrease or absence of
urine urobilinogen. Have to interpret using fecal and blood analysis. No
confirmatory test available.
 Urobilinogen is very unstable in acid urine (so best to test after meal when
urine is more alkaline) and easily photo oxidizes to urobilin.

114
Q

Reaction interferences

A

 No interference from large molecules, glucose and urea and radiographic
dye and plasma expanders
 Reason for difference in refractometer reading
 Slight elevation from protein
 Decreased readings: urine pH 6.5 or higher
 Interferes with indicator; add 0.005 to the reading; readers automatically add
this

115
Q

Clinical significance

Increased Fat metabolism=
primary causes=
Ketonuria shows=

A

 Increased fat metabolism = inability to metabolize
carbohydrate
 Primary causes
- Diabetes mellitus
- Vomiting (loss of carbohydrates)
- Starvation, malabsorption, dieting (↓ intake)
 Ketonuria shows insulin deficiency
- Monitor diabetes

116
Q

Diabetic ketoacidosis=

A

 Diabetic ketoacidosis = increased accumulation of
ketones in the blood
 Electrolyte imbalance, dehydration, and diabetic coma

117
Q

Ketonuria unrelated to diabetes

A

 Inadequate intake/absorption of carbohydrates
 Vomiting
 Weight loss
 Eating disorders
 Frequent strenuous exercise

118
Q

Multisitix Ehlichs aldehyde reaction

A

 Multistix: Ehrlich’s aldehyde reaction
 p-dimethylaminobenzaldehyde (Ehrlich reagent); report in Ehrlich units
(EU) 1 EU = 1 mg/dL
 Normal readings 0.2 to 1, abnormal 2, 4, 8
 Light to dark pink

119
Q

Chemostrip diazo reaction

A

 Chemstrip: diazo (azo-coupling) reaction
 4-Methoxybenzene-diazonium-tetrafluoroborate; more specific than
Ehrlich reaction; report in mg/dL
 White to pink

Urinalysis and Body Fluids 4214 (14 decks)

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