1 / 17

MLAB 2401: Clinical Chemistry Keri Brophy- M artinez

MLAB 2401: Clinical Chemistry Keri Brophy- M artinez. Assessment o f Iron, Porphyrins and Others. Laboratory Evaluation of Iron Metabolism. Hematocrit Hemoglobin Red cell count + indices Total iron TIBC Percent saturation Transferrin Ferritin. Specimen Requirements: Iron Studies.

skip
Download Presentation

MLAB 2401: Clinical Chemistry Keri Brophy- M artinez

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. MLAB 2401: Clinical ChemistryKeri Brophy-Martinez Assessment of Iron, Porphyrins and Others

  2. Laboratory Evaluation of Iron Metabolism • Hematocrit • Hemoglobin • Red cell count + indices • Total iron • TIBC • Percent saturation • Transferrin • Ferritin

  3. 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

  4. Iron Panels • Three components • Total serum iron • Reflects the amount of ferric iron bound to transferrin • Does not include free iron found in hemoglobin • TIBC= Total Iron Binding Capacity • Measures capacity to bind iron with transferrin • Sum of the serum iron and the UIBC • Percent Iron Saturation/Transferrin Saturation • Ratio of serum iron to TIBC

  5. Assessing Iron Levels and Forms • Directly measured • Iron • Transferrin • Useful to diagnose hypochromic anemias • Measured by the amount of iron it can bind • Ferritin • Best diagnostic test for IDA • Reflects iron stores • Acute phase reactant

  6. Assessing Iron Levels and Forms • Indirect measure • TIBC (Total iron-binding capacity) • Measures the total amount of iron that apotransferrin can bind • TIBC= serum iron + unsaturated binding capacity • Can be expressed as a percentage=percent saturation • Ratio of serum iron to TIBC % Iron Saturation= (Total iron/TIBC) X 100

  7. Test Methodologies: Iron • Colorimetric Procedure • Separate Fe from transferrin with a strong acid • Iron is reduced from ferric(Fe3+)to ferrous(Fe2+) state • Addition of a chromogen creates a colored compound • Measurement of colored product by spectrophotometry

  8. Iron Reference Ranges • Diurnal variation • Men • 65-175 µg/dL • Women • 50-170 µg/dL • Decreased Levels • Decreased intake • Increased need • Increased loss • Increased Levels • Increased absorption • Lead poisoning • Pernicious anemia • Megaloblastic anemia • Hepatitis

  9. Test Methodologies:TIBC & UIBC 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

  10. Reference Ranges • Transferrin • 200-360 mg/dL • Ferritin • Male: 20-250 ng/mL • Female: 10-120 ng/mL • TIBC • 250-425 µg/dL • % saturation • 15-50%

  11. Test Methodology: Porphyrins • Screening tests • Urinary porphobilinogen (PBG) • Urinary aminolevulinic acid (ALA) • Urinary porphyrins • Quantitative Assays • URO • PROTO • COPRO • Serve to classify porphyrias

  12. Specimen Requirements:Porphyrias • Protect specimens from light • Urine samples • Fresh • Random • 24-hour sample with no preservative • Blood samples • Whole blood • Plasma

  13. Testing:Porphyrias • Ehrlich Watson test –outdated test to differentiate between urobilinogen and porphobilinogen. • Urobilinogen is extractable into either chloroform or butanol. • Porphobilinogen is neither, and is left behind. • Hoesch rapid screening test for porphobilinogen • Fluorescent technique for other porphyrins. • Mauzerall-Granick–more reliable screening test

  14. 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

  15. Specimen Requirements: Lead • Whole blood • Why? Circulating lead found in the RBC • Royal blue top with EDTA anticoagulant • EDTA • Lead-free containers • Venous sample preferred • Capillary specimens can be used for screening • Urine

  16. Lab Method: Lead • Test methodologies • AAS • Anodic stripping voltammetry • Reference Ranges in blood • Children: < 10 µg/dL • Adult :<25 µg/dL

  17. References • Bishop, M., Fody, E., & Schoeff, l. (2010). Clinical Chemistry: Techniques, principles, Correlations. Baltimore: Wolters Kluwer Lippincott Williams & Wilkins. • http://www.clsi.org/source/orders/free/h17-a.pdf • Sunheimer, R., & Graves, L. (2010). Clinical Laboratory Chemistry. Upper Saddle River: Pearson .

More Related