11 Appendix
301-7146 English Rev B 11/02/2011 Operator’s Manual NA 229
Blood
This pseudo-enzymatic test contains organic peroxide and a chromogen.
The peroxidase effect of hemoglobin and myoglobin causes a color
change to green.
• Expected Values: Normal urine contains no detectable hemoglobin
or intact red blood cells. Any positive results should be further
evaluated.
• Sensitivity: 0.02 mg/dL blood
• Performance Characteristics: Intact and lysed red blood cells are
both detected by the assay, which contains lysing agents to lyse intact
red blood cells releasing hemoglobin. A hemoglobin concentration of
0.015 – 0.062 mg/dL is approximately equivalent to 5 – 20 intact red
blood cells per microliter.
• Limitations: Reducing agents such as ascorbic acid, uric acid,
glutathione and gentisic acid may cause false negative results.
Samples with a pH of 5 may interfere with the test. Preservatives
(formalin) and cleaning agents such as hypochlorite may result in
false positives. High concentrations of nitrite can delay the reaction.
There is no interference from specific gravity for this test. Ascorbic
acid concentrations ≥ 300 mg/dL may interfere with the test. MESNA
concentrations ≥ 1140 mg/dL may cause false negative results.
pH
This test contains a mixed indicator which assures a marked change in
color between pH 5 and pH 9. Colors range from orange through yellow
and green to cyan.
• Expected Values: The normal pH of urine can vary between pH 5.0
and pH 9.0
• Performance Characteristics: pH values are determined in units of
1.0 over the range from 5.0 to 9.0.
• Limitations: Same as manual.
Nitrite
This test is based on modified Griess reaction in which nitrite in the urine
reacts with amide to form a diazonium compound. The subsequent
coupling reaction yields a pink color in the presence of nitrite. Some Gram
positive and non-nitrite-forming bacteria are not detected in this test.
• Expected Values: Normal urine contains no detectable nitrite.
However, a negative result does not rule out a urinary tract infection.
• Sensitivity: 0.04mg/dL nitrite
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