TEST PRINCIPLE REAGENT COLOR/REACTION
Double sequential enzyme reaction M - glucose oxidase, peroxidase, CHROMOGENS:
Glucose potassium iodide
C - glucose oxidase, peroxidase,
•
•
O-toluidine (pink to purple)
Potassium iodide (blue to brown)
(Correlated with ketones) ENZYMES:
tetramethylbenzidine • Aminopropryl-carbazol (yellow to orange- brown)
Glucose oxidase peroxidase • Tetramethylbenzidine (yellow to green)
TIME FALSE (+) FALSE (-)
Contamination by oxidizing agents and detergents • High levels of ascorbic acid, ketones, specific gravity
30s • Low temperature
• Improperly preserved specimens
TEST PRINCIPLE REAGENT COLOR/REACTION
Sodium nitroprusside reaction M — sodium nitroprusside (acetoacetic acid) CHROMOGENS:
Ketones C— sodium nitroprusside + glycine
(acetoacetic acid & acetone)
(Correlated with glucose) ENZYMES:
TIME FALSE (+) FALSE (-)
• Phthalein dyes, highly pigmented red urine, levodopa • Improperly preserved specimens
40 s • Medications containing free sulfhydryl groups
TEST PRINCIPLE REAGENT COLOR/REACTION
• pKa change of polyelectrolyte M — poly (methy Ivinyl ether/maleic anhydride) CHROMOGENS:
Specific • pKa = dissociation constant bromthymol blue
C — ethyleneglycol-Bis (aminoethylether)
Gravity ENZYMES:
bromthymol blue
TIME FALSE (+) FALSE (-)
High concentrations of proteins because of protein anions • Highly alkaline urines (>6.5)
45s • Add 0.005 to S.G. readings
TEST PRINCIPLE REAGENT COLOR/REACTION
Double-indicator system • Methyl red CHROMOGENS:
pH • Bromthymol blue
(Correlated with Nitrite, ENZYMES:
LE, microscopic)
TIME FALSE (+) FALSE (-)
None Runover from the adjacent CHON pad may lower pH
60s
TEST PRINCIPLE REAGENT COLOR/REACTION
Protein error of indicators M — tetrabromphenol blue CHROMOGENS:
Protein C — tetrachloropenol tetrabromosulfonphthalein
(Correlated with blood, ENZYMES:
nitrite, LE, microscopic)
TIME FALSE (+) FALSE (-)
• Highly buffered alkaline urine Proteins other than albumin
60s • High specific gravity pigmented specimens, phenazopyridine
quaternary ammonium compounds (detergents) antiseptics,
chlorhexidine loss of buffer from prolonged exposure of reagent
strip To the specimen
• It is important to interpret protein result by correlating it with specific gravity. Trace of protein in DILUTE URINE – indicates greater loss of protein than a
trace amounts in concentrated specimen.
TEST PRINCIPLE REAGENT COLOR/REACTION
Pseudo-peroxidase activity of M — diisopropylbenzenedehydroperoxide tetramethylbenzidine CHROMOGENS:
Blood hemoglobin C — dimethyldihyroperoxide- tetramethylbenzidine
(Correlated with protein ENZYMES:
and microscopic)
TIME FALSE (+) FALSE (-)
• Strong oxidizing agents, bacterial peroxidases • High specific gravity/crenated cells
60s • Menstrual contamination • High concentration of nitrite
• Formalin, captopril
• Ascorbic acid >25 mg/dl
TEST PRINCIPLE REAGENT COLOR/REACTION
Diazo reaction M — 2,4-dichloro-analine diazonium salt CHROMOGENS:
Bilirubin C -2, 6-dichorobenzene-diazonium-tetrafluoroborate
(Correlated with ENZYMES:
urobilinogen)
TIME FALSE (+) FALSE (-)
Highly pigmented urines, phenazopyridine, indican metabolites of Lodine Specimen exposure to light, ascorbic acid >25 mg/dl, high
60s concentrated of nitrite
TEST PRINCIPLE REAGENT COLOR/REACTION
Ehrlich's reaction M — para-dimethylaminobenzaldehyde CHROMOGENS:
Urobilinogen C — 4-methoxybenzenediazonium-tetrafluroborate
(Correlated with bilirubin)
ENZYMES:
TIME FALSE (+) FALSE (-)
M — porphobilinogen, indican, p-aminosallcyclic acid, sulfonamides, M — Old specimens, preservation in formalin
60 s methyldopa, procaine, chlorpromazine, highly pigmented urine C —old specimens, preservation in formalin, high concentration of
C — highly pigmented urine nitrite
TEST PRINCIPLE REAGENT COLOR/REACTION
Greiss reaction M — p-arsanilic acid Tetrahydrobenzo (h)-quinolin-3-ol CHROMOGENS:
Nitrite C— Sulfanilamide, hydroxytetrahydro benzoquinoline
ENZYMES:
(Correlated with protein,
LE and microscopic)
TIME FALSE (+) FALSE (-)
• Improperly preserved specimens • Non-reductase-containing bacteria
60s • highly pigmented urine • insufficient contact between bacteria and urinary nitrate (should be 4 hours)
lack of urinary nitrate,
• large quantities of bacteria converting nitrite to nitrogen,
• presence of antibiotics
• high concentration of ascorbic acid
• If the uniform pink color is VERY LIGHT, it may BEST BE SEEN by placing the strip AGAINST A WHITE BACKGROUND. The test is reported as (+) or (-).
TEST PRINCIPLE REAGENT COLOR/REACTION
Leukocyte esterase M — derivatized pyerole amino acid ester, diazonium salt CHROMOGENS:
Leukocytes C — indoxylcarbonic acid ester diazonium salt
(Correlated with protein, ENZYMES:
nitrite and microscopic)
TIME FALSE (+) FALSE (-)
Strong oxidizing agents, Formalin, highly pigmented urine, nitrofurantoin High concentration of protein, glucose, oxalic acid, ascorbic acid,
120s gentamicin, cephalosporins, tetracyclines
