Urinalysis and Body Fluids CRg Unit 3Chemical Examination of UrinePart 1 – Overview of Procedure & pH Unit Outline• Introduction to reagent strip testing• pH• Glucose & Carbohydrates• Ketones• Protein• Bilirubin• Urobilinogen• Blood• Leukocyte esterase• Nitrite• Miscellaneous Chemical Exam of Urine• Reagent strip manufactures• Siemens Multistix 10 SG• Roche ChemstripIllustration of Multistix 10 SGChemical Exam of Urine• Dipping methodChemical Exam of UrineSources of ErrorSource of ErrorWhat is going on?How to prevent it.Testing cold samplesChemical reactions slowed Test fresh / RT samplesSpecimen not mixedBlood cells have settled to bottom and not in contact Test well mixed sample.Over-dipping stripReagents get leached outDip completely, but brieflyInadequate blotting / fail to keep strip levelOver-run or mixing ofchemicalsBlot away excess urine and keep strip horiziontalImproper timingOver / under development of reagent pad colorsFollow manufacturer’s recommendationsInadequate lightingPoor lighting results in mis-interpretation of resultsWork in well lighted areaMis-using color chartMis-interpretation of resultsAlign reagent pad with proper part of color chart.Chemical Exam of Urine• Handling and Storage of Strips• Keep strips in original container• Store in cool (below 30C, but not refrigerated, not frozen)• Protect from moisture and volatile fumes• Keep bottle tightly closed• Keep desiccant in bottle • Remove strips immediately prior to use• Do not touch reagent pad areas • Use before expiration date• Do not use if pads are discoloredQuality Control• Use commercially prepared positive and negative controls.• at least once per 24 hours,• and anytime a new bottle is opened, • or question of validity of results. • Readings should agree with published results ± one color block.• Be aware of manufacturer’s stated limitationsChemical Exam of Urine - pH• pH definition: Negative log of the hydrogen ion concentration• Kidneys have major role in regulation of acid/base balance .•Kidneys & Lungs are major players in body acid/base balance. ••** The over-all goal is blood pH 7.40 ± .005.Chemical Exam of Urine - pH• No normal values• urine pH is a reflection of blood pH• Kidneys capable of 4.5-8.0 • In this hemisphere, first morning urine samples usually have an acid pH (@ 6.0)• Dipstick range is 4.5 - 9.0.• Kidneys are not able to produce urine with pH of 9 (either normally or abnormally)• pH of 9 associated with old sample / UTIFluctuations in Urine pHSituationReason / effectsUrine pH During sleepMetabolism continues; but respiration decreasedpH decrease(more acid) Following mealsStomach acids being absorbed into foodspH increases(more alkaline)General dietWestern diets of high meat = Acid urinesEastern diets of vegetables = Alkaline urinesSpecific foodsExample: metabolism of cranberries produces quinaldic acid pH decrease(more acid) Metabolic disordersExample: diabetes mellitus. Patientproduces keto-acidspH decrease(more acid) DrugsIn-advertent affects of medicationDrugs designed to control pH, as to limit kidney stone formationdependsUrine pH: Significance • Persistent AcidityPersistent Alkalinity Acidifying drugsAlkaline drugsDehydrationAcute and Chronic renal failureDiabetesDiureticsDiarrheaRenal tubular acidosisFeverUrinary tract infectionsGoutHigh protein dietsPulmonary emphysemaChemical Exam of Urine - pH• Urine pH Measurement• Purpose / reasons• Although rarely diagnostic, measurement of urine pH can be used to indicate overall body acid / base status• Medical management of pH• Crystals and renal calculi may form depending on urinary pH. • Identify crystals by the urine's pH.•Use the pH to assist in the identification of urine crystals.• Urine pH Measurement• Methods• pH meter•Overkill of technology, so rarely required.• pH papers• Litmus paper• Nitrazine paper • Reagent dipsticks▸Chemical Exam of Urine - pH• Acid indicator – methyl red• Alkaline indicator – bromthymol blue• Read 60 seconds after dipping• pH ranges from 5.0 to 8.5 in half unitspH color chart Chemical Exam of Urine - pHGlucoseBilirubinKetonesSpecific GravityBloodpHProteinUrobilinogenNitriteLeukocyte EsterasepH Over-Run PhenomenonChemical Exam of Urine - pHBuffers from the protein area of the strip (with their pH of 3.0) spill over to the pH area of the strip and make the pH of the sample appear more acidic than it really is.In - Summary • Store reagent strips in their bottle with lid closed at room temperature.• Do not expose strips to • Sunlight• Heat• Cold • Volatile substances• Moisture (each bottle contains a desiccant)• Only remove the number of strips you need for immediate testing.• Do not use strips that have discolored pads.• Do not use expired reagent strips.• Test urine which is brought to room temperature. • Run appropriate QC and only release patient results if controls perform as expected.• Kidneys are capable of producing urine with pH 4.5 – 8.0• Strips capable of providing results from @ 4.5 – 9.0• pH indicators methyl red and – bromthymol blue provide results• Be aware of ‘run-over’ and work to prevent it. Please credit those whose work and pictures I have used throughout these prsentations. Lillian Mundt & Kristy Shanahan, Graff’s Textbook of Urinalysis and Body Fluids, 2ndEd. Susan Strassinger & Marjorie Di Lorenzo, Urinalysis and Body Fluids, 5thEd.  Wikipedia, the free encyclopedia  www.wikibedia.org Siemens corporation, Healthcare division, Laboratory Diagnostics website  http://www.medical.siemens.com/ Roche Diagnostics http://www.roche.comReference ListingChemical Exam of