Outline topic # 7
URINALYSIS- Reagent Strip,( Chemical )
MLT 310-Urinalysis & OBF
Dr. Bernard C. Silvala/Dr. Ernesto Ramirez
URINALYSIS:
Reagent Strips:
Chemical Analysis of Urine
Most common abnormalities
Increased amounts of:
 Sugars
 Protein
 RBCs
 WBCs
 Bilirubin
 Ketones
 urobilinogen
Sample reagent strips
Multistix
Chemstrip
Rapignost
Comstix SG
N-multistix
Reagent Strips:
Chemical principles employed on all reagent strips are essentially the same
Reporting of Results:
a. in concentration (mg/dL)
b. small, mod., large
c. 1+, 2+, 3+, 4+
d. as positive, negative, or normal
* exceptions: pH and sp.gr.
Procedure
Dip into urine specimen (briefly)
Remove excess urine
Read at specified time
Compare color rxn
Note
Reading time
Highly pigmented specimens
Interfering substances
Proper storage of dipsticks
Specimen used
Analytes
- pH
- Specific gravity
- Blood
- Nitrite
- Protein
Outline topic # 7
URINALYSIS- Reagent Strip,( Chemical )
MLT 310-Urinalysis & OBF
Dr. Bernard C. Silvala/Dr. Ernesto Ramirez
- glucose
- Ketones
- Bilirubin
- Urobilinogen
- Leukocytes
pH:
– Indicators: methyl red, bromthymol blue
– Sensitivity: 5 – 9
– Affecting factors: bacterial growth & metabolism may cause marked increase; test is
not affected by CHON or other endogenous substances; leaching/run-over
Specific Gravity:
 Reagents: polyelectrolyte, bromthymol blue, buffer
 Sensitivity: 1.000 – 1.030
 Affecting factors:
o LOW: pH (add 0.005 for ph >6.5), glucose
o HIGH: protein, urea, ketones, lactic acids
Blood:
 Reagents: H2O2, tetramethylbenzidine, or orthotoluidine
 Sensitivity: 5-20 RBCs; 0.05-0.3 mg/dL Hgb
 Affecting factors: oxidizing contaminants (FP), ≥5 mg/dL ascorbic acid (FN),
myoglobin should be ruled out (via dilution 1:40), high nitrite (FN),
Protein:
 Reagents: citrate buffer at pH 3
 Sensitivity: 5-20 mg/dL albumin
 Affecting factors: highly buffered alkaline urine may cause a false-positive result
Glucose:
 Reagents: glucose oxidase, peroxidase, orthotoluidine, KI, aminopropylcarbazol
 Sensitivity: 0.1 g/dL
 Affecting factors: ≥50 mg/dL ascorbic acid may inhibit the reaction
Ketones:
 Reagents: sodium nitroprusside
 Affecting factors: highly volatile; bacteria can degrade
Bilirubin:
 Reagents: dichloroaniline dichlorobenzene diazonium tetrafluoroborate
 Sensitivity: 0.4-0.8 mg/dL
 Affecting factors: unstable in light; large amounts of ascorbic acid or nitrite lower
results, FP due to abnormal urine color
Outline topic # 7
URINALYSIS- Reagent Strip,( Chemical )
MLT 310-Urinalysis & OBF
Dr. Bernard C. Silvala/Dr. Ernesto Ramirez
Urobilinogen:
 Reagents: dimethylaminobenzaldehyde
 Sensitivity: 0.2-8 Erlich units
 Affecting factors: unstable; fresh specimen required; FN – formalin
Leukocytes/LE:
 Reagents: indoxylcarbonic acid ester, diazonium salt
 Sensitivity: 5-15/hpf intact or lysed leukocytes w/ esterases
 Affecting factors:
 FP w/ histiocytes & trichomonads, vaginal contamination
 FN high sp. Gr, drugs, oxidizing agents, high glu & CHON
 Agranulocytes are not detected
 Detects WBC even when they have been lysed
Nitrite:
 Reagents: para-arsanilic acid, tetrahydrobenzoquinolin-3-ol
 Sensitivity: ≥105 bacteria/mL
 Affecting factors:
 bacteria w/o reductase do not react
 ≥25 mg/dL ascorbic acid may inhibit reaction
 <4H retention of urine in bladder
 Lack of dietary nitrate
 Contamination doesn’t cause FP