Leukocytes: The test reveals the presence of granulocyte esterases. These esterases cleave an indoxyl ester, and the indoxyl so liberated reacts with a diazonium salt to produce a violet dye.
Leukocyte estefpe results may be positive in the absence of observable cells if the leukocytes have lysed. Positive results may occasionally be found with random specimens from females due to contarination of the specimen by vaginal discharge. Elevated glucose concentrations (55-110 mmolL) or high specific gravity may cause decreased test results. The presence of cephalexin, cephalothin, tetracycline may cause decreased reactivity, and high levels of the drug may cause a false negative reaction. The test area does not react with lymphocyte.
Ketone: This test is based on the principle of Legal's test and is more sensitive to acetoacetic acid than to acetone.
The reagent area does not react with p-hydroxybutyric acid. Some high specific gravity/low pH urines may give reactions up to and including Trace Normal urine specimens usually yield negative results with this reagent. False positive results (Trace) may occur with highly pigmented urine specimens or those containing large amounts or levodopa metabolites.
Nitrite: The test is based on the principle of Griess's test and is specific to nitrite. Any degree of uniform pink colour development should be interpreted as a positive. Nitrite test suggesting the presence of 10' or more organisms per mL, but colour development is not proportional to the number of bacteria present. A negative result does not in itself prove that there is no significant bacteriuria. Negative results may occur when urinary tract infections are cause by organisms which do not contain reductase to convert nitrate to nitrite, when urine has not been retained in the bladder long enough (4-&hrs) for reduction of nitrate to occur, or when dietary nitrate is absent, even if organisms containing reductase are present and bladder incubation is ample. Ascorbic acid concentrations of 1 4mmolI. or greater may cause false negative results with specimens containing nitrite ion concentrations of 58umol/L, or less
Urobilinogen: This test is based on the Ehrlich reaction The reagent area may react with interfering substances known to react with Ehrlich's reagent. Excreted pigments and medicaments that have a red colomaton in acidic medium may produce false positive results. This test is inhibited by elevated concentrations of formaldehyde. Strip reactivity increases with temperature; the optimum temperature is 22C to 26C. The absence of urobilinogen cannot be determined with this test.
Billrubin: This test is based on the coupling of bilirubin with diazonium salt in an acid medium.
Normally no bilirubin is detectable in urine by even the most sensitive methods. Even trace amounts of bilirubin are sufficiently abnormal to require further investigation. Some urine constituents (medicines, urinary indicants) may produce a yellowish or reddish discoloration of the test paper that may interfere with interpreting the result. Ascorbic acid concentrations of 1,4mmol/L or greater may cause false negatives.
Protein: The test is based on the principle of the protein error of a pH indicator.
The reagent area is more sensitive to albumin. An elevated pH (up to 9) may affect the test. The residues of disinfectants containing quaternary ammonium groups or chlorohexidine are present in the urine vessel maybe lead to a false positive result.
Glucose: The test is based on the specific glucose oxidase/peroxidase reaction.
The test is spocific for glucose, no substance excreted in urine other than glucose is known to give a positive result.
1.4mmolL and/or high Ketone concentrations (8mmoVL) may cause false negatives for specimens containing small amounts of glucose (5.5mmolL). The reactivity of the glucose test decreases as the SG of the urine increases. False positive reactions may be caused by hypochlorite peroxide (cleaning agents). Reactivity may also vary with temperature.
Specific Gravity: This test contains a detergent and Bromthymol blue that indicates the presence of ionic constituents in the urine by changing colour from green to yellow. The specific gravity test permits determination of urine specific gravity between 1.005 and 1.030. In general, it correlates within 0.005 with value obtained with the refractive index method. Strips are automatically adjusted for pH by the instrument when pH>7.0 or pH <5.0. Highly buffered alkaline urine may cause low readings relative to other methods. Elevated specific gravity readings may be obtained in the presence of modera quantities (5g/L.) of protein.
Blood: Hemoglobin and myoglobin catalyze the oxidation of the indicator by means of organic hydroperoxide contained in the test paper. This test is highly sensitive to hemoglobin and thus complements the microscopic examination. The sensitivity of this test may be reduced in urit with high specific gravity. The test is equally sensitive to myoglobin as to hemoglobin. Captopril and Lodine may also cause decreased reactive Blood is often found in the urine of menstruating females. Certain oxidizing contaminants, such as hypochlorite, may produce false positive resul Microbial peroxidase associated with urinary tract infection may cause a false positive reaction. Ascorbic acid concentrations greater than 1 4mmo may cause false negatives at the trace levels
pH: This test contains a mixed indicator which assures a marked change in colour between pH4.5 and pH9.
pH: bromxylenol blue 3.3mg; bromocresol green 0.2mg.
Please refer to the User's manual of the Uritest/URIT urine analyzer.
Use only clean vessels to collect urine. False-positive readings for blood and glucose can result from residues of strongly oxidizing disinfectants in the specimen collection vessel. Do not add preservatives to the urine. Do not expose urine specimens to sunlight as this induces oxidation of bilirubin and urobilinogen and hence leads to artificially low results for these two paraments.
Incorrect results may be obtained when you shake the strip in specimen container. The dipping time is too short or too long may result in a negative error.