Zinc protoporphyrin (ZPP) Test

Zinc protoporphyrin (ZPP) is a compound found in red blood cells. it is normally in small amounts, but the level may increase in people with lead poisoning and iron deficiency. This test measures the level of ZPP in the blood.

There are two types of test available to measure the level of ZPP in the blood.

  • Free erythrocyte protoporphyrin (FEP) test. This test measures both ZPP, which accounts for 90% of protoporphyrin in red blood cells, and free protoporphyrin, which is not bound to zinc.
  • ZPP/heme ratio. This test gives the proportion of ZPP compared to the normal iron-containing heme in red blood cells.


The ZPP concentration in blood is usually very low.

  • An increase in ZPP indicates a disruption of normal heme production without the specific cause. The main reasons behind the increase are lack of iron or (and) lead exposure.
  • An increase in the ZPP/heme ratio in a child is mostly due to iron deficiency.
  • A decreasing ZPP/heme ratio over time following iron supplementation likely demonstrates successful treatment.

Things you must keep in mind:

Before the evaluation, a person’s history, clinical findings, and the results of other tests, such as ferritin, lead, and a complete blood count (CBC) should be examined. The possibility exists that the person may have both iron deficiency and lead poisoning.

Keywords: Zinc protoporphyrin; ZPP; FEP; heme; lead posioning; iron deficiency

* The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.