Protoporphyrin, Free Erythrocyte, and Zinc Protoporphyrin

CPT: 84202
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Test Details


  • FEP
  • ZPP

Test Includes

Zinc protoporphyrin and free erythrocyte protoporphyrin


Fluorescent substances in plasma may interfere with hematofluorometer results.2 Skin contamination may lead to false elevations. Both this test and blood lead are needed for full evaluation.



Reference Interval

Environmental exposure:

• FEP, blood: Adults: 0−34 μg/dL

• ZPP, blood: Adults: 0−38 μg/dL; occupational exposure: BEI® (sampling time is after one month's exposure): 100 μg/dL1

Additional Information

“Free” protoporphyrin is noncomplexed, nonheme protoporphyrin. Lead poisoning is also characterized by elevated plasma and urine δ-aminolevulinic acid and increased urinary coproporphyrin. Urinary porphobilinogen and uroporphyrin are normal to slightly increased.3 Free erythrocyte protoporphyrin is a sensitive test for lead toxicity or chronic exposure in adults. Erythrocyte protoporphyrin levels should not be used as a screening test for lead poisoning in children.4 The diagnosis of lead exposure or poisoning includes consideration of environmental exposure, as well as symptoms and abnormal erythrocyte protoporphyrin. This test is not to be used for workplace exposure to lead. If lead testing is required for workplace exposure to lead, please order test 010169.

Increased lead absorption is reported in the presence of iron deficiency.5

Specimen Requirements


Whole blood


7 mL

Minimum Volume

0.2 mL


Royal blue-top (EDTA) tube or tan-top lead-free tube; submit original tube.


Mix tube thoroughly to avoid clotting.

Storage Instructions

Maintain specimen at room temperature.

Stability Requirements



Room temperature

14 days


14 days

Causes for Rejection

Clotted specimen; frozen specimen

Clinical Information


1. BEI® (Biological Exposure Indices) based on 1994-1995 Recommendations of the American Conference of Governmental Industrial Hygienists (ACGIH).
2. Marsh WL Jr, Nelson DP, Koenig HM. Free erythrocyte protoporphyrin (FEP) I. Normal values for adults and evaluation of the hematofluorometer. Am J Clin Pathol. 1983 Jun; 79(6):655-660. 6846255
3. Chisholm JJ. Increased lead absorption and lead poisoning. In: Behrman RE, Vaughan VC III, Nelson WE, eds. Nelson Textbook of Pediatrics. 13th ed. Philadelphia, Pa: WB Saunders Co;1987:1507-1511.
4. DeBaun MR, Sox HC Jr. Setting the optimal erythrocyte protoporphyrin screening decision threshold for lead poisoning: A decision analytic approach. Pediatrics. 1991 Jul, 88(1):121-131. 2057248
5. Carraccio CL, Bergman GE, Daley BP. Combined iron deficiency and lead poisoning in children. Effect on FEP levels. Clin Pediatr (Phila). 1987 Dec; 26(12):644-647. 3677534


Bird TD, Wallace DM, Labbe RF. The porphyria, plumbism, pottery puzzle. JAMA. 1982 Feb 12; 247(6):813-814. 7057560
Schreiber WE. Iron, porphyrin and bilirubin metabolism. In: Kaplan LA, Pesce AJ, eds. Clinical Chemistry−Theory, Analysis, and Correlation. 2nd ed. St Louis, Mo: Mosby-Year Book Inc; 1989:496-511.
Zanella A, Gridelli L, Berzuini A, et al. Sensitivity and predictive value of serum ferritin and free erythrocyte protoporphyrin for iron deficiency. J Lab Clin Med. 1989 Jan; 113(1):73-78. 2909654


Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
010165 Protoporphyrin, FEP/ZPP 012090 Protoporphyrin (FEP) ug/dL 2892-8
010165 Protoporphyrin, FEP/ZPP 012079 Zinc Protoporphyrin ug/dL 2895-1

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