Protoporphyrin (Blood)

Does this test have other names?

Protoporphyrin, ZPP, zinc protoporphyrin test, erythrocyte protoporphyrin test

What is this test?

The protoporphyrin test is used to diagnose blood abnormalities caused by lead. The test can indicate lead exposure or lead poisoning. Lead poisoning is extremely dangerous because lead can damage organs throughout the body.

Lead poisoning does not always cause symptoms, so a blood test may be the only way to confirm lead exposure or poisoning. (Doctors usually order a protoporphyrin test after a simple blood screening shows elevated levels of lead.) The test can also identify an iron deficiency anemia or other types of anemia.

The protoporphyrin test doesn't measure the levels of lead in the blood. Instead, it measures how the blood has been affected by lead. Lead can impair the blood's ability to create new blood cells. The protoporphyrin test measures the effects of lead exposure that have happened over the past two to three months. 

Why do I need this test?

You may need this test if you have symptoms of iron deficiency or lead poisoning, including:

  • Repeated miscarriages or fertility problems

  • Digestive problems such as nausea or constipation

  • High blood pressure

  • Fatigue

  • Weakness

  • Hearing problems

  • Difficulty concentrating

  • Seizures

  • Nerve damage 

You may need this test if the result from your blood lead screening is 25 micrograms per deciliter (mcg/dL) or higher. Children may have the protoporphyrin test to confirm lead poisoning. You may need this test if you have been exposed to lead or if your health care provider suspects that you have lead poisoning or an iron deficiency.  

What other tests might I have along with this test?

You may need a number of other tests along with a protoporphyrin test, including:

  • Complete blood count

  • Blood erythrocyte protoporphyrin test

  • Reticulocyte count, or a count of young red blood cells

  • Serum iron, iron binding capacity, ferritin levels, or other measurements of iron in the blood

  • X-rays 

What do my test results mean?

Many things may affect your lab test results. These include the method each lab uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your health care provider.

Test results showing zinc protoporphyrin levels higher than 50 mcg/dL indicate an elevated level of lead in the blood.

How is this test done?

The test requires a blood sample, which is drawn through a needle from a vein in your arm. 

Does this test pose any risks?

The risks are very minor. The finger prick or needle may feel uncomfortable or painful. You may experience bruising, soreness, or pain in your hand or arm at the puncture spot. These symptoms usually go away soon after the test is over.

What might affect my test results?

Only exposure to lead should affect your test results. 

How do I get ready for this test?

A blood test rarely requires any preparation. You can probably eat, drink, and take your medication as usual, but check with your doctor to be sure. Remember to tell your doctor about any medications or supplements that you take. Your doctor will also tell you if you need to skip any of your regular medications on the day of the test.