Chemical Examination of Urine - PowerPoint PPT Presentation

Loading...

PPT – Chemical Examination of Urine PowerPoint presentation | free to download - id: 432927-NDQyO



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

Chemical Examination of Urine

Description:

Chemical Examination of Urine Ricki Otten MT(ASCP)SC uotten_at_unmc.edu Objectives: Review the objectives on page 1 and 2 of the lecture handout Objectives marked with ... – PowerPoint PPT presentation

Number of Views:1657
Avg rating:3.0/5.0
Slides: 79
Provided by: webmediaU
Learn more at: http://webmedia.unmc.edu
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Chemical Examination of Urine


1
Chemical Examination of Urine
  • Ricki Otten MT(ASCP)SC
  • uotten_at_unmc.edu

2
Objectives
  • Review the objectives on page 1 and 2
  • of the lecture handout
  • Objectives marked with will not be tested
    over during student lab rotation

3
Historical Perspective Urinalysis
  • Physical examination of urine
  • Odor
  • Taste
  • Color
  • Clarity

4
Historical Perspective
  • Chemical examination of urine
  • Limited reactions
  • Required large volumes of urine
  • Large volumes of reagent
  • Performed in test tubes
  • Time consuming and cumbersome
  • Clinical usefulness was not realized
  • Not routinely ordered

5
Historical Perspective
  • Microscopic examination of urine
  • Not until invention of the microscope
  • Then clinical usefulness realized

6
Reagent Strip Testing
  • Technology and necessity
  • Chemical reactions miniaturized
  • Required less urine
  • Test results within minutes
  • Easy to perform
  • Increased test utilization

Brunzel, 2nd Ed, page 124
7
Reagent Strip Testing
  • Ideal qualitative screening tool
  • Sensitive Low concentration of substances
  • Negative result normal
  • Specific Reacts with only one substance
  • False negative and false positive
  • Cost effective Relatively inexpensive tool that
  • provides information about the health status
  • of the patient

8
Reagent Strip Testing
  • Chemically impregnated absorbent
  • pads attached to an inert plastic strip
  • Each pad is a specific chemical reaction that
  • takes place upon contact with urine
  • Chemical reaction causes the color of the pad to
  • change
  • Color compared to a color chart for interpretation

9
Reagent Strip Testing
  • Qualitative or semi-quantitative results
  • Concentration units (mg/dl)
  • Negative, small, moderate large
  • Negative, 1, 2, 3, 4
  • Timing of chemical reactions is CRITICAL
  • Shortest time requirement on one end of strip 30
    sec
  • Longest time requirement on the other 2 min

10
Reagent Strip Testing
  • Principle of chemical reactions
  • False negative reactions
  • False positive reactions
  • Color interferences
  • Alternative testing used to confirm results that
    you may think are invalid due to
  • Interfering substance
  • Color interference (called color masking)

11
Care and Storage (pg 4)
Reading assignment Textbook, chapter 7 Page
124-130
Confirmatory Testing (pg 6)
12
Confirmatory Testing
  • Alternative testing establishes the correctness
    or accuracy of another procedure
  • Often used when urine is highly pigmented
  • Bilirubin reagent strip ? ictotest

13
Confirmatory Testing
  • Characteristics
  • Differ in sensitivity
  • Ictotest vs Bilirubin reagent strip
  • Differ in specificity
  • SSA vs Protein reagent strip
  • Clinitest vs Glucose reagent strip
  • Differ in methodology/reaction

Ideallywant all 3
14
Differ in Specificity
  • Clinitest reacts with all reducing
  • substances
  • Glucose reagent strip reacts with only one
    reducing substance glucose

15
  • 10 reagent strip tests
  • Specific gravity
  • pH
  • Protein
  • Glucose
  • Ketones
  • Blood
  • Bilirubin
  • Urobilinogen
  • Nitrite
  • Leukocyte Esterase
  • Purpose of the test
  • What is normal
  • What is abnormal
  • Reaction
  • Causes of invalid results

16
Specific Gravity Purpose
  • Evaluates the concentrating and diluting
  • ability of the kidney
  • Density is related to the amount of substances
    (solutes) in solution
  • Increased density increased solute in solution
    hypertonic urine concentrated urine
  • Decreased density decreased solute in solution
    hypotonic urine dilute urine

17
Specific Gravity Normal
  • Normal 1.002 1.035
  • Majority of urines 1.010 1.025
  • Physiologically impossible 1.000
  • gt1.040
  • Dependent upon hydration status

18
Specific Gravity Terms
  • Isosthenuria
  • Fixed at 1.010
  • Renal tubules lost absorption and secreting
    capability
  • Hypersthenuria
  • Increased specific gravity
  • Concentrated urine
  • Hyposthenuria
  • Decreased specific gravity
  • Dilute urine

Sensitivity issues Pregnancy testing Urinary
tract infection
19
Specific Gravity Methods
  • Methods of measurement
  • Reagent strip test indicates ionic solutes
  • Refractometer indicates amount of total solutes
  • Two functions of the kidney
  • Maintain water balance
  • Maintain electrolyte homeostasis

Performed by renal tubules through concentrating
and diluting reabsorbing and secreting water and
electrolytes (ionic)
20
Specific Gravity Reaction
  • Based on a change in the pKa of a polyelectrolyte
    on the reagent pad
  • Increased ions in solution causes the
    polyelectrolyte on the pad to produce free H
  • Free H cause a change in pH on the reagent pad
  • Change in pH bromthymol blue indicator

21
Specific Gravity Reaction
22
Specific Gravity
  • Sensitivity 1.000
  • Specificity detects only ionic substances
  • Radiographic dye
  • Mannitol
  • Glucose

Does not interfere
23
pH Purpose
  • Kidneys regulate bodys acid-base
  • balance by selective handling of H and HCO3-
  • Urine pH reflects acid-base status of body
  • Treatment protocol may require urine pH be
    maintained at a specific pH
  • (Aids in identification of crystals (microscope))

24
pH Normal
  • Normal ranges from 4.5 8.0
  • First morning void acidic
  • Physiologically impossible lt4.5
  • gt8.0
  1. Urine not handled properly
  2. Old urine
  3. Treatment induced

25
pH Interpretation
  • Made in conjunction with
  • Acid-base status
  • Renal function
  • Presence of infection in urinary tract
  • Diet high protein, low protein
  • Medications
  • Age of urine sample

26
pH Abnormal
  • Acid
  • Respiratory acidosis
  • High protein diet
  • Starvation
  • UTI
  • Alkaline
  • Respiratory alkalosis
  • Vegetarian diet
  • Renal tubular acidosis
  • UTI

27
pH Reaction
  • Double indicator system
  • Methyl red
  • Bromthymol blue
  • Amount of free H influences acidity of urine and
    cause pH indicator to change color

Needed to measure the wide pH range acid to
alkaline
28
pH
  • Invalid test results due to
  • Improper handling of urine sample
  • Contamination of urine vessel prior to collection
  • Run-over phenomenon

29
Protein Purpose
  • Normal kidneys secrete LITTLE protein
  • lt15 mg/dl (or lt150 mg/24 hours)
  • The protein that is found in urine comes from
  • Bloodstream
  • Urinary tract
  • Proteinuria is an indicator of early renal
    disease
  • Proteinuria also caused by non-renal disease

30
Renal Cause of Proteinuria
  • Glomerular damage
  • Most serious cause of proteinuria
  • Most common cause of proteinuria
  • Glomerulonephritis
  • Nephrotic Syndrome
  • Tubular dysfunction
  • Reabsorption capability decreased
  • Toxin exposure, inherited disorder
  • Fancons syndrome heavy metal poisoning

31
Classification of Proteinuria
  • Functional
  • Orthostatic (postural)
  • Transient
  • Pathologic
  • Pre-renal (overflow)
  • Renal glomerular
  • Renal tubular
  • Post-renal

32
Protein Methods
  • Reagent strip test
  • SSA test
  • Foam test
  • Micro-albumin test

33
Protein Reagent Strip
  • The reagent pad is held at a
  • constant pH of 3 by a buffer
  • Proteins (anions) in solution cause an
  • indicator dye to release H causing a color
  • change
  • Protein error of indicators

34
Protein Reagent Strip
  • Sensitivity 10-25 mg/dl
  • Specificity reacts with albumin
  • False positive highly alkaline urine (pH gt 8.0)
  • False negative
  • Dilute urine
  • Presence of other proteins
  • (Tamm-Horsfall, globulins, myoglobin,
  • free light chains, hemoglobin)

35
Protein SSA (Extons Test)
  • Sulfosalicylic Acid (SSA) Precipitation Test
  • Acid will precipitate proteins out of solution
    causing the solution to become cloudy
  • Amount of cloudiness is related to the amount of
    protein present

36
Protein SSA (Extons Test)
  • Amount of cloudiness is evaluated, thus must use
    centrifuged urine
  • Sensitivity 5-10 mg/dl
  • Specificity detects all protein

37
Protein SSA (Extons Test)
  • False positive results
  • Radiographic dyes
  • Turbid urine
  • Uncentrifuged urine
  • False negative results
  • Highly alkaline urine
  • Dilute urine

38
Protein Foam test
  • Shake aliquot of urine and observe color of
    resulting foam
  • White foam protein present

39
Protein Micro-albumin test
  • Measures very low concentration of albumin
    (better sensitivity than reagent strip test for
    albumin)
  • Management of diabetic patient
  • Methods vary reagent strip test,
  • immunochemical reaction

40
Glucose Purpose
  • Healthy normal urine does not contain glucose
  • Normally, glucose is filtered by the glomerulus
    and is reabsorbed back into the bloodstream
    through active transport mechanism
  • Glucose in urine is pathologic

41
Glucose Purpose
  • Glucosuria
  • Glycosuria
  • Caused by renal and non-renal disease
  • Pre-renal glycosuria plasma glucose level
    exceeds renal threshold (diabetes mellitus)
  • Renal glycosuria plasma glucose level below
    renal threshold, but tubules cannot reabsorb
    glucose back into bloodstream

Terms used interchangeably
42
Reducing Substances Purpose
  • Reducing Substances
  • Glucose
  • Other sugars galactosemia (inherited metabolic
    disorder)

43
Glucose, Reducing Substances
  • Normal negative
  • Abnormal
  • Diabetes mellitus glucose
  • Impaired renal tubular reabsorption glucose
  • Inborn error of metabolism galactosemia

44
Methods
  • Reagent strip detects only glucose
  • Copper Reduction detects reducing substances

45
Glucose Reagent Strip
  • Detects only glucose
  • Double sequential enzyme reaction

46
Glucose Reagent Strip
  • Sensitivity 30 mg/dl
  • Specificity
  • Reacts only with glucose
  • False positive
  • Strong oxidizing agents (bleach)
  • Peroxides
  • False negative
  • Ascorbic acid (reducing agent)
  • Improperly stored urine glycolysis

47
Clinitest Reaction
  • Copper Reduction Test
  • Reducing substances are able to reduce copper
    sulfate to cuprous oxide
  • Pass-through phenomenon
  • All children lt2 years metabolic disorder
  • (galactosemia)

48
Clinitest Reaction
  • Sensitivity 250 mg/dl
  • Specificity
  • Reacts with all reducing substances
  • Reducing sugars glucose, galactose, fructose,
    lactose, maltose (NOT SUCROSE)
  • False positive any reducing substance
  • (Ascorbic acid)
  • False negative radiographic dye

49
Ketones Purpose
  • Ketones are intermediary products of fat
    metabolism

50
Ketones
  • Three ketone bodies
  • Acetone 2
  • Acetoacetic acid 20
  • Beta-hydroxybutyric acid 78
  • Characteristic fruity breath acetone

51
Ketones Normal
  • Normal negative
  • Abnormal
  • Inability to utilize carbohydrates
  • Excessive loss of carbohydrates
  • Inadequate intake of carbohydrates

52
Ketones Methods
  • Reagent strip
  • Acetest tablet test

53
Ketones Method
  • Glycine also measures acetone
  • Reagent strip check package insert
  • Acetest tablets contain glycine

54
Ketones
  • Reagent strip
  • Sensitivity 5-10 mg/dl
  • Specificity acetoacetic acid and/or acetone
  • False positive highly pigmented urine
  • False negative improper specimen handling
  • Acetest
  • Specificity acetoacetic acid and acetone
  • False positive highly pigmented urien
  • False negative improper specimen handling

55
Blood Purpose
  • Blood in urine indicates pathology
  • Two forms found in urine
  • Intact RBC
  • Hemolyzed RBC

56
Blood Terms
  • Hematuria
  • Hemoglobinuria
  • Myoglobinuria

All will give a positive blood reaction
57
Blood Reagent strip
  • Test can detect hemolyzed RBC
  • Heme moiety imparts peroxidase activity and
    catalyzes the reaction

58
Blood
  • Sensitivity
  • Specificity
  • Intact RBC
  • Hemolyzed RBC (hemoglobin)
  • Myoglobin
  • False positives myoglobin, oxidizing agents
  • False negatives ascorbic acid

59
Blood
  • Correlate reagent strip results
  • Microscopic findings
  • Color and clarity

60
Bilirubin and Urobilinogen
  • Bilirubin in urine is always pathologic
  • liver disease
  • Urobilinogen in urine normal to have a small
    amount
  • 0.2 1.0 mg/dl

61
Three mechanisms
  • Pre-hepatic liver is healthy
  • Hepatic liver disease
  • Post-hepatic liver is healthy, obstruction
    indicated

62
Bilirubin Methods
  • Reagent strip
  • Ictotest tablet test
  • Foam test

63
Bilirubin Methods
  • Reagent strip
  • Ictotest tablet test
  • Same reaction
  • Same specificity conjugated bilirubin
  • False positive urine color
  • False negative low concentration, ascorbic acid,
    improper specimen handling

64
Bilirubin Methods
  • Reagent strip
  • Ictotest tablet test
  • Sensitivity differs
  • Reagent strip 0.5 mg/dl
  • Ictotest 0.05 0.1 mg/dl

65
Bilirubin Methods
  • Possible to have a negative reagent strip test
    and positive ictotest
  • Difference in sensitivity levels
  • Always perform Ictotest when
  • Urine bilirubin test specifically ordered
  • Urine appearance is amber even if bilirubin
  • reagent strip test is negative
  • Positive reagent strip test

66
Bilirubin Foam Test
  • Shake urine and observe resulting foam
  • Yellow foam bilirubin

67
Urobilinogen Methods
  • Reagent strip test
  • Two reactions dependent upon manufacturer
  • Para-dimethylaminobenzaldehyde
  • Diazonium salt
  • Cannot determine absence of UBG
  • Watson-Schwartz assay

68
Urobilinogen Methods
  • Para-dimethylaminobenzaldehyde
  • Sensitivity 0.2 mg/dl
  • Specificity
  • False positive any Ehrlich reactive compound
    color masking urine at body temp
  • False negative improper specimen handling
  • Diazonium salt
  • Sensitivity 0.4 mg/dl
  • Specificity reacts only with UBG
  • False positive color masking
  • False negative improper specimen handling

69
Urobilinogen Watson Schwartz
  • Classic method used to differentiate
  • urobilinogen from porphobilinogen using a
  • differential extraction method
  • Para-dimethylaminobenzaldehyde

70
Nitrite Purpose
  • Bacteria that contain a specific enzyme can
    reduce dietary nitrates to nitrites
  • Rapid screening test for UTI

71
Nitrite Normal
  • Normal negative
  • Abnormal
  • Cystitis bladder
  • Pyelonephritis kidney

72
Nitrite Method
  • Reagent strip test
  • Nitrite aromatic amine ? diazonium salt
  • Diazonium salt aromatic compound ?
  • pink color
  • Sensitivity 0.06-0.1 mg/dl nitrite
  • 10,000 organisms

73
Nitrite Method
  • Reagent strip test
  • Specificity
  • False positive improper specimen handling color
    masking
  • False negative bacteria cannot reduce nitrates
  • Bladder time not sufficient need 4 hours
  • Low nitrite levels
  • Ascorbic acid
  • Antibiotic inhibition of bacteria
  • Further reduction of nitrites to nitrogen

74
Leukocyte Esterase Purpose
  • Increased WBC in urine is pathologic
  • Indicates inflammation, infection
  • Neutrophils most common type of WBC found in
    urine
  • Can detect intact WBC and lysed WBC

75
Leukocyte Esterase Normal
  • Normal negative
  • Abnormal
  • Bacterial infection
  • cystitis, pyelonephritis, urethritis
  • Non-bacterial infection yeast, trichomonas

76
Leukocyte Esterase Method
  • Reagent strip
  • Granules in cytoplasm of WBC contain an enzyme
    (esterase)
  • Ester esterase? aromatic compound
  • Aromatic compound diazonium salt ?
  • Purple colored complex

77
Leukocyte Esterase
  • Sensitivity 5-15 WBC/hpf
  • Specificity
  • False positive vaginal contamination color
    masking
  • False negative strong oxidizing agents (bleach)
    lymphocytes (no granules)

78
(No Transcript)
About PowerShow.com