11 Appendix
301-7146 English Rev B 11/02/2011 Operator’s Manual NA 230
• Performance Characteristics: This test is specific for nitrite. Results
may depend on the ability of bacteria to reduce nitrate to nitrite, the
number of bacteria and the retention time of the urine in the bladder.
• Limitations: Food dyes and therapeutic pigments such as red beets
and pyridium may cause false positive responses. A negative
response in the presence of bacteriuria may be caused by the
following: non-nitrite producing microorganisms, low nitrate diet,
antibiotic therapy, strong diuresis, or insufficient urinary retention time
in the bladder. There is no interference from pH or 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.
Leukocytes
This enzymatic test pad contains an indoxyl ester and a diazonium salt.
Granulocyte esterases react with indoxyl ester and diazonium salt to
generate a violet color.
• Expected Values: Normal urine specimen should not produce a
positive result.
• Sensitivity: 15 WBCs/μL
• Performance Characteristics: Leukocyte test detects the presence
of esterase in the granulocytic white blood cells. The test result is
most frequently accompanied by the presence of bacteria that may or
may not produce a nitrite positive reaction.
• Limitations: False positive results may occur in the presence of
preservatives such as formaldehyde and formalin. High
concentrations of protein, glucose, cephalexin and gentamicin may
diminish the color response. Test results may be positive in the
absence of observable cells if the granulocytes have lysed. The test
can be negative in the presence of visible leukocytes if they have not
lysed and/or are not granulocytes. There is no interference from
specific gravity for this test. WBC readings at 75 cells/uL may be
increased at pH9. There is no interference from cephalosporins at 11
mg/dL. However, higher concentrations of cephalosporins may
interfere with the test. Boric acid concentrations ≥ 500 mg/dL may
interfere with the test. MESNA may produce false positive results.
Specific Gravity
Specific gravity is physically determined by refractometry in the Urine
Chemistry System and is not analyzed by strip chemistry.
To Next Page
Loading...