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90640:PROTOPORPHYRINS, FRACTIONATION, RBC
Methodology:High-Performance Liquid Chromatography (HPLC) with Fluorometric End Point
Edit Date:2/11/2010
Performed:Monday-Friday
Released:72 hours after setup at PeaceHealth Laboratories’ reference lab. Not reported Saturday or Sunday.
CPT Code:82491-90
Specimen Collection Details
Collection:One 4 mL green top tube (heparin). Also acceptable: One 4 mL lavender top tube (EDTA). Patient must be fasting 12-14 hours and abstain from alcohol for 24 hours.
Handling:Place on wet ice immediately. Transfer blood to a 12 mL graduated centrifuge tube. Centrifuge for 10 minutes at 2000 rpm. Record volume of packed cells. Discard supernatant plasma. Wash erythrocytes three times by resuspension in 5 mL of cold 0.9% saline. Resuspend packed cells to original volume with 0.9% saline and freeze in a plastic vial. Allow no more than one freeze/thaw cycle. Volume of packed cells and total volume of erythrocyte suspension (red cells + saline) are required for testing.
Stability:Frozen. Unstable ambient or refrigerated.
Standard Volume:4 mL red cell resuspension.
Minimum Volume:1 mL red cell resuspension.
Transport:Frozen on dry ice.
Rejection Criteria:Specimen frozen and thawed more than once; specimen other than heparin or EDTA; frozen whole blood.
Reference Range:
Includes separate quantitation of zinc protoporphyrins and free protoporphyrins.
Free Protoporphyrin <20 µg/dL packed cells
Zinc-Complexed Protoporphyrin <60 µg/dL packed cells

Values of zinc-complexed protoporphyrin >60 ug/dL suggest iron deficiency anemia or may indicate chronic intoxication by heavy metals or organic chemicals. A predominance of noncomplexed (free) protoporphyrin indicates a diagnosis of EPP.