Reagent Strip Reaction Flashcards
(119 cards)
1
Q
What is the Multistix reagent for specific gravity?
A
Poly (methyl vinyl ether/ maleic anhydride) bromthymol blue
2
Q
What is the Chemstrip reagent for specific gravity?
A
Ethylene glycol diaminoethyl ether tetraacetic acid bromthymol blue
3
Q
What causes false positive interference in specific gravity?
A
High concentration of protein
4
Q
What causes false negative interference in specific gravity?
A
Highly alkaline urine; pH >6.5
5
Q
What should be added to correct specific gravity if pH >6.5?
A
Add 0.005
6
Q
What are the reagents for strip reaction for pH?
A
Methyl red and bromthymol blue
7
Q
What interferes with reagent strips for pH?
A
Runover from adjacent pads, old specimens
8
Q
What correlates with pH on reagent strips?
A
Nitrite, Leukocytes, Microscopic examination
9
Q
What is the test for microalbuminuria?
A
Micral test
10
Q
What is the principle of the micral test for albuminuria?
A
Enzyme-immunoassay
11
Q
What are the reagents for the micral test?
A
Gold-labeled antibody, B-galactosidase, chlorophenol red galactoside
12
Q
What is the sensitivity of the micral test?
A
0-10 mg/dL
13
Q
What causes false negative interference in micral and immunodip tests?
A
Dilute urine
14
Q
What is the principle of the Immunodip test for microalbuminuria?
A
Immunochromographics
15
Q
What is the sensitivity of the Immunodip test?
A
1.2-8.0 mg/dL
16
Q
What are the reagents for the Immunodip test?
A
Antibody-coated blue latex particle
17
Q
What is the principle of the albumin:creatinine ratio in Clintest/multistix pro?
A
Sensitive albumin tests related to creatinine concentration to correct for patient hydration
18
Q
What are the reagents for albumin in albumin:creatinine ratio (Clintest/Multistix Pro)?
A
Diiodo-dihydroxydinitrophenyl tetrabromosulfonphthalein
19
Q
What are the reagents for creatinine in albumin:creatinine ratio (Clintest/Multistix Pro)?
A
Copper sulfate, tetramethylbenzidine, diisopropylbenzene dihydroperoxidase
20
Q
What is the sensitivity for albumin in albumin:creatinine ratio?
A
10-150 mg/L
21
Q
What is the sensitivity for creatinine in albumin:creatinine ratio?
A
10-300 mg/dL (0.9-26.5 mmol/L)
22
Q
What interferes with albumin:creatinine ratio tests?
A
Visibly bloody or abnormally colored urine; creatinine: cimetidine false positive
23
Q
How does the protein reagent strip work?
A
By accepting hydrogen ions from the indicator
24
Q
What is the reagent for protein in Multistix?
A
Tetrabromophenol blue (citrate buffer at pH 3.0)
25
What is the reagent for protein in Chemstrip?
Tetrachlorophenol tetrabromosulfonphthalein (citrate buffer at pH 3.0)
26
What causes false positive protein interference?
Highly buffered alkaline urine, pigmented specimens, phenazopyridine, detergents, antiseptics, prolonged strip exposure, high specific gravity
27
What causes false negative protein interference?
Proteins other than albumin, microalbuminuria
28
To what is the protein indicator most sensitive?
Albumin
29
What correlates with protein on reagent strips?
Blood, nitrite, leukocytes, microscopic examination
30
What is the cold precipitation test for all forms of protein?
Sulfosalicylic acid precipitation test (Exton's test)
31
What is the reagent for SSA precipitation test?
Exton's reagent (3% SSA + Sodium sulfate)
32
What is the procedure for the SSA precipitation test?
3 mL of 3% SSA + 3 mL centrifuged urine or 3 mL 7% SSA + 11 mL centrifuged urine (10 mins incubation)
33
What indicates a positive result in the SSA test?
Cloudiness
34
What is the SSA turbidity grading for trace levels?
Noticeable turbidity; cannot see circle at tube bottom (6-30 mg/dL - Strasinger)
35
What is the SSA turbidity grading for 1+?
Distinct turbidity, no granulation (30-100 mg/dL - Strasinger)
36
What is the SSA turbidity grading for 2+?
No granulation or flocculation (100-200 mg/dL - Strasinger)
37
What is the SSA turbidity grading for 3+?
Turbidity with granulation and flocculation (200-400 mg/dL - Strasinger)
38
What is the SSA turbidity grading for 4+?
Clumps of protein (>400 mg/dL - Strasinger)
39
What is the SSA turbidity range for Henry's trace grading?
20 mg/dL
40
What is the SSA turbidity range for Henry's 1+ grading?
50 mg/dL
41
What is the SSA turbidity range for Henry's 2+ grading?
200 mg/dL
42
What is the SSA turbidity range for Henry's 3+ grading?
500 mg/dL
43
What is the SSA turbidity range for Henry's 4+ grading?
1.0 g/dL
44
What causes a strip positive but SSA negative result?
Highly buffered alkaline urine with no albumin present (false positive strip) or albumin present (false negative SSA)
45
What is the correction for strip positive and SSA negative results?
Acidify urine to pH 5.0 and retest
46
What causes a strip negative but SSA positive result?
Radiographic contrast media, drugs (tolbutamide, penicillins, cephalosporins, sulfonamides)
47
How to differentiate strip negative and SSA positive results?
Examine precipitate microscopically; drugs/dyes form crystals, protein forms amorphous precipitates
48
What can cause negative protein results despite significant proteinuria?
Excessively diluted urine
49
What should be considered when evaluating urine protein?
Specific gravity, as trace protein in dilute specimens is more significant
50
What enzymes are involved in the glucose reagent strip?
Glucose oxidase, Peroxidase
51
What are the reagents for glucose in Multistix?
Glucose oxidase, peroxidase, potassium iodide
52
What is the color range for glucose in Multistix?
Blue to green to brown
53
What is the reagent for glucose in Chemstrip?
Glucose oxidase, peroxidase, tetramethylbenzidine
54
What is the color range for glucose in Chemstrip?
Yellow to green
55
What causes false positive glucose strip results?
Oxidizing agents, detergents
56
What causes false negative glucose strip results?
High levels of ascorbic acid, ketones, high specific gravity, low temperature, improperly preserved specimen
57
What was the first dip-and-read reagent strip developed in 1950?
Glucose strip by Miles Inc.
58
What is the sensitivity of the glucose reagent strip?
100 mg/dL
59
What are other chromogens used for glucose determination?
Aminopropylcarbazole (yellow to orange brown), o-toluidine (pink to purple)
60
What is the correlation of glucose with other reagent strips?
Ketones, Proteins
61
What is the principle of the ketones reagent strip?
Sodium nitroprusside reaction (Legal's test)
62
What are the reagents for ketones in the reagent strip?
Sodium nitroprusside/nitroferricyanide, Glycine (Chemstrip)
63
What causes false positive results for ketones in reagent strips?
Phthalein dyes, pigmented red urine, levodopa, drugs with sulfhydryl groups
64
What causes false negative results for ketones in reagent strips?
Improperly preserved specimens
65
When is acetone detected in reagent strips?
When glycine is present
66
What is the correlation of ketones with other tests?
Glucose
67
What percentage of ketones is beta-hydroxybutyric acid?
0.78
68
What percentage of ketones is acetoacetic acid?
0.2
69
What percentage of ketones is acetone?
0.02
70
What is the first ketone formed (parent ketone)?
Acetoacetic acid/diacetic acid
71
What is the composition of the Acetest tablet?
Sodium nitroprusside, disodium phosphate, glycine, lactose
72
What is the reagent for blood in Multistix?
Diisopropylbenzene dihydroperoxidase tetramethylbenzidine
73
What is the reagent for blood in Chemstrip?
Dimethyldihydroperoxyhexane tetramethylbenzidine
74
What causes false positive results for blood in reagent strips?
Strong oxidizing agents, bactericidal peroxidases, menstrual contamination
75
What causes false negative results for blood in reagent strips?
High specific gravity, crenated cells, formalin, captopril, nitrite, ascorbic acid >25 mg/dL, unmixed specimen
76
What does a uniform green color for blood in reagent strips indicate?
Hemoglobin/Myoglobin
77
What does a speckled or spotted pattern in blood reagent strips indicate?
Hematuria (presence of RBCs)
78
What does Chemstrip contain to eliminate ascorbic acid interference?
Iodate overlay
79
What hemoglobin level produces a positive protein reagent strip reaction?
>10 mg/dL
80
What is the correlation of blood with other tests?
Protein, Microscopic
81
What is the bilirubin reagent in Multistix?
2,4-Dichloroaniline diazonium salt
82
What is the bilirubin reagent in Chemstrip?
2,6-Dichlorobenzene diazonium salt (tetrafluoroborate)
83
What causes false positive results for bilirubin in reagent strips?
Highly pigmented urines, phenazopyridine, indican metabolism of iodine
84
What causes false negative results for bilirubin in reagent strips?
Specimen exposure to light, high nitrite, ascorbic acid >25 mg/dL
85
What is the correlation of bilirubin with other tests?
Urobilinogen
86
What is the composition of the Ictotest tablet for bilirubin?
p-Nitrobenzene-diazonium p-toluenesulfonate, SSA, Na2CO3, Boric acid
87
What is the confirmatory test for bilirubin in urine?
Ictotest
88
What is the sensitivity of the Ictotest?
Detects 0.05 to 0.1 mg/dL bilirubin
89
What is the urobilinogen reagent in Multistix?
p-Dimethylaminobenzaldehyde (PDAB or Ehrlich reagent)
90
What is the urobilinogen reagent in Chemstrip?
4-Methoxybenzene-diazonium tetrafluoroborate (specific for UBG)
91
What causes false positive results for urobilinogen in reagent strips?
Ehrlich-reactive compounds (porphobilinogen, indican, methyldopa, procaine, sulfonamides, p-aminosalicylic acid, chlorpromazine), pigmented urine
92
What causes false negative results for urobilinogen in reagent strips?
Old specimen, formalin preservative, high concentration of nitrite
93
What is the correlation of urobilinogen with other tests?
Bilirubin
94
What is the leukocyte reagent in Multistix?
Derivative of pyrrole amino acid ester, diazonium salt
95
What is the leukocyte reagent in Chemstrip?
Indoxycarbonic acid ester, diazonium salt
96
What causes false positive results for leukocytes in reagent strips?
Strong oxidizing agents, formalin, highly pigmented urine, nitrofurantoin
97
What causes false negative results for leukocytes in reagent strips?
High concentration of protein, glucose, oxalic acid, ascorbic acid, gentamicin, cephalosporins, tetracyclines, inaccurate timing, crenated leukocytes
98
What is the correlation of leukocytes with other tests?
Protein, nitrite, microscopic
99
Which cells contain esterase?
Neutrophils, eosinophils, basophils, monocytes, histiocytes, trichomonas
100
Which cells do not contain esterase?
Lymphocytes
101
What can produce pyuria without bacteriuria?
Trichomonas, chlamydia, yeast, and interstitial nephritis
102
What is p-arsanilic acid used for?
Nitrite detection
103
What is the nitrite reagent in Multistix?
p-Arsanilic acid, tetrahydrobenzo(h)-quinolin-3-ol
104
What is the nitrite reagent in Chemstrip?
Sulfanilamide, hydroxytetrahydrobenzoquinoline
105
What causes false positive results for nitrite in reagent strips?
Improperly preserved specimen, highly pigmented urine
106
What causes false negative results for nitrite in reagent strips?
Nonreductase-containing bacteria, insufficient contact time, lack of urinary nitrate, bacteria converting nitrite to nitrogen, antibiotics, high ascorbic acid, high specific gravity
107
What do pink spots or edges in nitrite indicate?
Negative
108
What does positive nitrite correspond to?
100,000 organisms/mL
109
If the nitrite test is negative- can UTI be ruled out?
No
110
What organisms can cause UTIs with negative nitrite tests?
Gram-positive cocci and yeast
111
Where can dietary nitrate be found?
Green vegetables
112
What is the correlation of nitrite with other tests?
Protein, leukocyte, microscopic
113
What is the 11th reagent pad in a dipstick test?
Ascorbic acid
114
What is the principal metabolite of ascorbic acid?
Oxalate
115
How does ascorbic acid interfere in reagent strip tests?
It interferes with hydrogen peroxide or diazonium salt
116
What tests show false negatives due to ascorbic acid?
Blood, Bilirubin, Leukocyte, Nitrite, Glucose (BBLNG)
117
When should ascorbic acid be read on Chemstrip?
10 seconds
118
When should ascorbic acid be read on Multistix?
60 seconds
119
What is a more accurate and quantitative method for ascorbic acid?
GC-MS (Gas Chromatography-Mass Spectrometry)
