How the Test is Performed

A blood sample is needed. For information on how this is done, see: Venipuncture

The sample is then placed in ice and taken immediately to the laboratory. Three porphyrins can normally be measured in small amounts in human blood. They are:

• Coproporphyrin
• Protoporphyrin (PROTO)
• Uroporphyrin

Protoporphyrin is normally found in the highest amount. More tests are needed to show the levels of specific porphyrins.

How to Prepare for the Test

You should not eat for 12 - 14 hours before this test. You may drink water right before the test. Failure to follow these restrictions may affect the test results.

How the Test Will Feel

When the needle is inserted to draw blood, you may feel moderate pain, or only a prick or stinging sensation. Afterward, there may be some throbbing.

Why the Test is Performed

This test is used to diagnose porphyrias, a group of rare disorders often passed down through family members.

It may also be used along with other tests to diagnose lead poisoning and certain nervous system and skin disorders.

Normal Results

This test specifically measures total porphyrin levels, but reference values (a range of values seen in a group of healthy people) for the individual components are also included:

• Total porphyrin levels: 16 to 60 mcg/dL
• Coproporphyrin levels: < 2 mcg/dL
• Protoporphyrin levels: 16 to 60 mcg/dL
• Uroporphyrin levels: < 2 mcg/dL

Note: mcg/dL = micrograms per deciliter

Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

The examples above show the common measurements for results for these tests. Some laboratories use different measurements or may test different specimens.

What Abnormal Results Mean

Increased levels of coproporphyrins may be a sign of:

• Congenital erythropoietic porphyria
• Hepatic coproporphyria
• Sideroblastic anemia
• Variegate porphyria

Increased protoporphyrin levels may be a sign of:

• Anemia of chronic disease
• Congenitalerythropoietic protoporphyria
• Increased erythropoiesis
• Infection
• Iron deficiency anemia
• Lead poisoning
• Sideroblastic anemia
• Thalassemia
• Variegate porphyria

Increased uroporphyrin levels may be a sign of:

• Congenital erythropoietic porphyria
• Porphyria cutanea tarda

Risks

Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight but may include:

• Excessive bleeding
• Fainting or feeling light-headed
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)

Alternative Names

Protoporphyrin levels; Porphyrins - total; Coproporphyrin levels; PROTO test

References

Anderson KE. The porphyrias. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 229.

Wiley JS, Moore MR. Heme biosynthesis and its disorders: porphyrias and sideroblastic anemias. In: Hoffman R, Benz EJ Jr., Shattil SJ, et al, eds. Hoffman Hematology: Basic Principles and Practice. 5th ed. Philadelphia, Pa: Churchill Livingstone Elsevier; 2008:chap 38.

Update Date: 2/28/2012

Reviewed by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.