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MLAB 2401: Clinical Chemistry Keri Brophy- M artinez. Chapter 5: Assessment o f Iron, Porphyrins and Others. Specimen Requirements: Iron Studies. Serum without anticoagulant Plasma with heparin ( check product insert) Oxalate, citrate or EDTA binds Fe ions, so they are unacceptable

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mlab 2401 clinical chemistry keri brophy m artinez

MLAB 2401: Clinical ChemistryKeri Brophy-Martinez

Chapter 5: Assessment of Iron, Porphyrins and Others

specimen requirements iron studies
Specimen Requirements: Iron Studies
  • Serum without anticoagulant
  • Plasma with heparin ( check product insert)
    • Oxalate, citrate or EDTA binds Fe ions, so they are unacceptable
    • Early morning sample preferred due to diurnal variation
  • No hemolysis
iron study profiles
Three Components

Total Iron ( serum )

TIBC

% Iron Saturation ( Fe Sat )

The Iron Saturation is a measurement of how “full” transferrin is

Iron Study/Profiles
assessing iron levels and forms
Assessing Iron Levels and Forms
  • Directly measured
    • Iron
    • Transferrin
      • Beta globulin formed in the liver
      • Measured by the amount of iron it can bind
    • Ferritin
      • Best diagnostic test for IDA
      • Acute phase reactant
assessing iron levels and forms1
Assessing Iron Levels and Forms
  • Indirect measure
    • TIBC (Total iron-binding capacity)
      • Measures the total amount of iron that apotransferrin can bind
      • Can be expressed as a percentage(percent saturation)
          • Ratio of serum iron to TIBC
      • Increased
        • Late pregnancy
        • IDA
        • Following hemorrhage
        • Following destruction of liver cells
      • Decreased
        • Decreased synthesis of transferrin
        • Increased loss of urine proteins
test methodologies iron
Test Methodologies: Iron
  • Colorimetric Procedure
    • Separate Fe from transferrin with a strong acid
    • Iron is reduced from ferrous(Fe3+)to ferric(Fe2+) state
    • Addition of a chromogen creates a colored compound
    • Measurement of colored product by spectrophotometry
iron reference ranges
Iron Reference Ranges
  • Diurnal variation
  • Men: 65-165 µg/dL
  • Women: 45-160 µg/dL
  • Decreased Levels
    • Decreased intake
    • Increased need
    • Increased loss
  • Increased Levels
    • Increased absorption
    • Hemolytic anemia
    • Lead poisoning
    • Pernicious anemia
    • Megaloblastic anemia
    • Hepatitis
test methodologies tibc
Test Methodologies:TIBC

Pre-treatment and Colorimetric Method

  • Add Fe3+ to saturate binding sites on transferrin
  • MgCO3 is added to remove unbound Fe3+
  • Mixture is centrifuged and the supernatant tested using the serum iron methodology
reference ranges
Reference Ranges
  • Transferrin
    • 200-360 mg/dL
  • Ferritin
    • Male: 20-250 ng/mL
    • Female: 10-120 ng/mL
  • TIBC
    • 250-425 µg/dL
  • % saturation
    • 15-55
test methodology hemoglobin
Test Methodology: Hemoglobin
  • Electrophoresis
    • Discussed in separate unit
test methodology porphyrins
Test Methodology: Porphyrins
  • Screening tests
    • Urinary PBG
    • Urinary ALA
    • Urinayr porphyrins
  • Quantitative Assays
    • URO
    • PROTO
    • COPRO
  • Serve to classify porphyrias
lab methods
Lab Methods
  • Watson-Schwartz for Urinary PBG( porphobilinogen)
    • Screen for acute intermittent porphyria
    • Specimen
      • Qualitative: fresh morning urine
      • Quantitative: 24 hour collection
    • Reference Range
      • <2 mg/daily
watson schwartz
Watson-Schwartz
  • Principle
    • PBG + Ehrlich’s reagent results in a red-orange chromogen
    • Interferences
      • Urobilinogen
      • indole
lab methods hgba1c
Lab Methods: HgbA1c
  • Electrophoresis
  • Enzymatic Assays
  • HPLC
    • Goal is to separate hemoglobin forms within a column. Then, glycated versus total hemoglobin can be measured spectrophotometrically
    • Specimen requirements
      • EDTA whole blood
      • Can be non-fasting
  • Reference range
    • 4.0-6.0%
lab methods myoglobin
Lab Methods: Myoglobin
  • Procedures incorporate the binding of specific antibodies to myoglobin with a resulting chemical or physical change that can be measured and correlated to myoglobin concentration
  • Specimen requirements
    • Usually plasma ( check product insert)
specimen requirements lead
Specimen Requirements: Lead
  • Whole blood
    • Why? Circulating lead found in the RBC
    • Venous sample preferred but capillary sample can be used ( must confirm positive on capillary)
    • Royal blue top with EDTA anticoagulant
    • Lead-free containers
  • Urine
lab method lead
Lab Method: Lead
  • Test methodologies
    • AAS
    • Anodic stripping voltammetry
  • Reference Ranges in blood
    • Children< 10 µg/dL
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