Presentation on theme: "REAGENT STRIPS Storage Handling"— Presentation transcript:
1REAGENT STRIPS Storage Handling Protect from moisture and excessive heat.Store at room temp. Do not refrigerate.Keep container tightly capped.Do not remove desiccant from container.Do not use beyond expiration date.HandlingReview manufacturer’s instructions with each new lot numberRemove strips from bottle for immediate use. Recap.Check for discoloration.Keep away from bleach, acids, fumes, etc.
2REAGENT STRIPS (continued) Testingwithin 30 minutes to 2 hoursfresh, well-mixed, unspunat room temperatureDo not touch test pad areaDip briefly, but completely - app. 1 secondDrain off excess urine, avoid runoverDo not lay strip on benchCompare test areas to color chart on bottleRead at specified timesKnow sources of error, interfering substances, sensitivity, and specificity for each strip.When automated, follow instrument’s operating manual.
3Reporting Standard terms must be used Quantitative Qualitative Concentration mg/dLPlus systemQualitativeSmall, moderate, largeNegative/positive/WRR (normal)
4pHThe strip contains the indicators methyl red and bromthymol blue. The give colors over the pH range of 5-9. Colors range from orange through yellow and green to blue.Reference value on normal diet to 8.0
5CLINICAL SIGNIFICANCE pH Acid pH <6.0Diet (high protein, meat, cranberries)Acidifying drugs to prevent alk. stone formationAbnormal crystalluria (bilirubin, cystine, tyrosine, leucine, cholesterol )Uric acid stone formersAcidosis and uncontrolled Diabetes mellitusHypokalemiaStarvation
6pH (continued) Alkaline pH >6.5 Diet (vegetarian and citrus fruits) Alkaline tide produced after a mealMetabolic and respiratory alkalosisRenal tubular diseases (Fanconi’s syndrome)Alkalizing drugs to treat acid calculi formationGenitourinary tract infectionspH >8.0Contamination or old urine (not suitable for testing)
7ProteinReagent strip testing is based on the principle of protein error of the indicators. Protein in the form of albumin accepts ions from the indicator, which is buffered in a very acid medium. Color changes from shades of green to blue.Most significant for early detection of renal disease.
8CLINICAL SIGNIFICANCE PROTEIN Reference valueRandom urine negative (not detectable) <10mg/dL)24 Hour <150mg or 10 mg/dLCompositionAlbumin, 1/3aGlobulins, 2/3Tamm-Horsfall mucoprotein (25%)Pathology >30mg/dL or on daily outputHeavy >3g/dayModerate >1-3 g/dayMinimal <1g/day
9CLINICAL SIGNIFICANCE PROTEIN (CONTINUED) BenignFunctionalexercise, fever, stress, exposure to coldOrthostaticpositional, renal congestionPregnancytransient, investigate causePathologicPrerenal: overflow of low mole weight proteinsIgG light chains (Bence Jones proteins)acute phasehemoglobin, myoglobin
10CLINICAL SIGNIFICANCE PROTEIN (CONTINUED) PathologicRenal Glomerular PatternGroup A strep and SLE glomerulonephritisHypertensive and diabetic nephropathyNephrotic syndrome, tumors, infections, toxic agentsRenal Tubular PatternAcute and chronic pyelonephritisInterstitial nephritisRenal tubular acidosis, rejection of kidney transplantPost RenalInflammation/infection bladder, renal pelvis, ureter, prostate, external genitalia
11SSA Testing for Protein When mixed with weak sulfosalicylic acid (SSA), all urine proteins will denature and precipitate at room temperature. The degree of which is graded and reported in semi-quantitative terms.Albumin, globulins, glycoproteins, and Bence-Jones protein are detected.False positive caused by x-ray contrast media, penicillin, sulfonamides, tolbutamidesFalse negative caused by highly alkaline urine
12MicroalbuminuriaProtein (albumin) that cannot be detected by routine dipstick for proteinSensitive methods needed to detect 10-20mg/L or 1-2 mg/dLImmunochemicalDye bindingClinical significanceEarly management of kidney disease in diabetes, hypertension, or peripheral vascular disease
13GlucoseThe dipstick determination of glucose is based on a double sequential enzymatic reaction using the specific glucose oxidase/peroxidase reaction in the presence of glucose and a chromogen.The Clinitest or Benedict’s Reaction is based on the ability of reducing substances to reduce copper sulfate to cuprous oxide in the presence of a chromogen, which changes color from blue to orange. Test is performed to screen for non-glucose reducing sugars in infants and children under 2 years old.
14Clinical Significance of Glucose Reference valueNo detectable amount present in urine by dipstick method (<50 mg/dl)Positive values found when renal threshold for glucose is exceeded ( mg/dl)Diabetes mellitus (DM)Impaired tubular reabsorptionPregnancy with latent DM
15COMPARISON of REAGENT STRIP vs. CLINITEST Strip Clinitest CausePositive Negative Sensitivity of methodsOxidizing contaminants/bleachDeteriorated Clinitest tabletsNegative* Positive Non-glucose reducing substanceDeteriorated reagent stripsReagent strip interferences *Ascorbic acid (vitamin C)
16KetonesConditions that result in increased and or incomplete fat metabolism can produce metabolic intermediary fat products in the urine and blood. The three ketone bodies present in urine are acetoacetic acid (20%), acetone (2%), and betahydroxybutyric acid (78%).Acetoacetic acid and acetone react with nitroprusside in an alkaline medium to form a violet dye complex. Basis of dipstick.Betahydroxybutyric acid is not detected with dipstick.
17Clinical Significance Acetone No detectable ketones present in normal urines.Positive valuesDiabetic ketosis (ketonuria)Loss of carbohydrates due to fever, vomiting, weight loss, starvation, diarrhea, stressLactic acidosis caused by liver/renal failure, salicylate overdoseInterfering factorsFalse positive: pigmented urinesFalse negative: delay in testing
18NitriteThis test depends on the conversion of nitrate to nitrite by the action on Gram negative bacteria that contain reductase enzymes in the urine.At the acid pH of the reagent area, nitrite in the urine reacts with an aromatic amine to form a diazonium salt, followed by a coupling reaction with benzoquinoline to produce a pink color.Three factors must be presentReductase producing bacteria must be presentUrine must be retained in bladder long enough to convert nitrates to nitrites (4 hours)Nitrates must be present
19CLINICAL SIGNIFICANCE NITRITE Reference valueNo nitrites presentUrine must be FRESHImproper storage will result in false positivePositive nitritesScreen symptomatic and asymptomatic UTICommon infecting organismsEnterobacter, Citrobacter, Escherichia, Proteus, Klebsiella, PseudomonasDefinitive diagnosis made by urine cultureNon-reductase producing microorganisms will be negative for nitrites
20Leukocyte EsteraseGranulocytic leukocytes contain esterase activity that catalyze the hydrolysis of an amino acid ester to form an aromatic compound which reacts with a diazonium salt to produce a color change from beige to purple on the dipstick pad.All positive reactions require a microscopic exam of the sediment.
21CLINICAL SIGNIFICANCE LEUKOCYTE ESTERASE Reference value0-5 white cells/hpffemales 0-8 WBC/hpf or app. 10 WBC/uL (vaginal discharge can cause false positive)Screens for urinary tract inflammationkidney (pyelonephritis)bladder (cystitis)urethra (urethritis)Leukocyturia can occur with or without bacteria
22LEUKOCYTE-NITRITE Combination on FRESH urine is Cost effective tool to screen for UTIProvides 97% predictive value for negative culture when both tests are negativeImproved care in asymptomatic patient
23BloodDipstick will detect blood by sensing heme that is present in red cell, hemoglobin, and myoglobin. Based on the pseudoperoxidase activity of heme in the presence of an organic peroxide and a benzidine chromogen.Hematuria: in tact red cells present in urine (scattered green dots)Hemoglobinuria: presence of hemoglobin from lysed red cell in urine (diffuse green color)Myoglobinuria: presence of heme protein from muscles in urine (diffuse green color)
24CLINICAL SIGNIFICANCE BLOOD Reference value0-5 erythrocytes/mL or 0-2 RBC/hpfHematuria - intact red cellsrenal disease, calculi, tumors, infectionsbleeding in kidneys or lower urinary tractHemoglobinuria - free hemoglobinintravascular hemolysis as seen in incompatible blood transfusions, AIHA, G6PD, etc.Myoglobinuria - heme muscle proteinacute destruction of muscle fibers (rhabdomyolysis)crush/trauma injuriesExcessive exercise can cause all above
26BilirubinThe heme released from red cells is converted to the yellow bile pigment biliribin by a series of complex reactions in liver. A small amount is excreted under normal circumstances and is not detected in the urine with the dipstick.When present, the Diazo Reaction is based on the coupling of bilirubin with a diazonium salt in an acid medium to form a colored azo-dye complex.
27Ictotest for Bilirubin Highly pigmented urines can cause false positive reactions. Confirmation is required by testing with the Ictotest tablet test for bilirubin.This diazo tablet method is very sensitive to low levels of bilirubin.Pigments will be removed by the absorbent pad supplied with the test.
28CLINICAL SIGNIFICANCE BILIRUBIN Reference valuenot detected with reagent strips <0.02 mg/dLPositive findingsobstruction to bile flow from livergallstones and neoplasms of pancreasinflammation and swelling of liver cellsacute viral hepatitis, drug indued cholestatsisacute alcoholic hepatits/cirrhosiscongenital hyperbilirubinemiasDublin-Johnson and Rotor
29UrobilinogenCollectively referred to as the end products of bilirubin metabolism. Colorless reduction product of bilirubin which is oxidized by normal intestinal bacteria to brown pigment that is excreted in the feces.Based on the Ehrlich Reaction in an acid medium to form a red color.
30CLINICAL SIGNIFICANCE UROBILINOGEN Reference valueup to 1 mg/dL or 1 Ehrlich Unitgreater in PM (alkaline tide after meals)up to 2 mg/dL transition from normal to abnormaldecrease or absence cannot be determined with stripIncreased valuesliver damage: viral hepatitis, cirrhosis, drugs, toxinsinfections of biliary tree (cholangitis)hemolytic anemias and intravascular hemolysisincreased enteric productionAbsentobstruction of bile ductabsence of intestinal flora
31UA BILIRUBIN & UROBILINOGEN in UNCOMPLICATED JAUNDICE Condition Bilirubin UrobilinogenNormal Negative up to 2 EU/dLHepatic Disease Positive Increased (+/-)Obstructive Disease Positive (+/-) AbsentHemolytic Disease Negative Increased
32QUALITY ASSURANCE Facilities and Resources Proficiency Testing OSHA complianceProficiency TestingPersonnelQualifications, education and training, competencyReviewProcedure ManualNCCLS GP2-A2Controls, Standards, ReagentsEquipment and InstrumentsReporting of Results
33COMPETENCY ALERTS REAGENT STRIP TESTING Directly ObserveFollowed SOP and manufacturer’s instructionlabeled date received, opened, expiredRemoved strip immediately before test runReplaced capPerformed test on well mixed, unspun urinePerformed daily maintenance/function checksInterpretation of color changes for strips or tabletsPerformed confirmatory testing as indicatedPerformed Clinitest on nursery or pediatric urinesFollowed SOP step-by-step
34COMPETENCY ALERTS (continued) Monitor and ReviewCompliance with QC as defined in SOPResults logged on scheduled frequency of useParallel testingPM and service logs signedCritical values reported on interim worksheets: WHO, WHAT, WHEN.Standard units of measure defined in SOP are used to report qualitative and quantitative results.
35COMPETENCY ALERTS (continued) Assessment of Test PerformanceProficiency testingInternal blind samples of known chemical concentrationProblem SolvingResolve discrepant resultsInvestigate and resolve delta checked resultsSpecimen referred for definitive testing (UA culture) based on reagent strip results. Policy defined in SOP.Resolution of “out-of-control” results for known reference controls.
36MICROSCOPIC EXAM of URINARY SEDIMENT CLIA’88 ComplexityModerateProvider Performed Microscopy (PPM)physician, midlevel practitioner, or dentistbrightfield or phase microscopySpecimen of ChoiceFresh first morning, midstream, clean catchExamine within 2 hoursSpecific gravity >1.010pH acid