Mlab 2401 clinical chemistry keri brophy m artinez
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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

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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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