Porphyrin Tests
- Also Known As:
- Uroporphyrin
- Coproporphyrin
- Protoporphyrin
- Delta-aminolevulinic Acid
- ALA
- Porphobilinogen
- PBG
- Free Erythrocyte Protoporphyrin
- FEP
- Formal Name:
- Porphyrins

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At a Glance
Why Get Tested?
To help diagnose and sometimes to monitor porphyrias
When To Get Tested?
When you have symptoms that suggest a neurologic porphyria (e.g., abdominal pain, tingling or numbness in the hands or feet, muscular weakness and/or alterations in thought or mood) or a cutaneous porphyria (e.g., redness, blistering, or scarring of sun-exposed skin)
Sample Required?
The sample type depends on the porphyrin tests ordered by the health care practitioner. It may include one or more of the following:
- A blood sample obtained by inserting a needle into a vein
- A random or 24-hour urine collection (urine must be protected from light during collection)
- A fresh stool sample that is not contaminated with urine or water
Test Preparation Needed?
If a neurologic porphyria is suspected, the sample should be collected during an acute attack.
You may be able to find your test results on your laboratory’s website or patient portal. However, you are currently at Testing.com. You may have been directed here by your lab’s website in order to provide you with background information about the test(s) you had performed. You will need to return to your lab’s website or portal, or contact your healthcare practitioner in order to obtain your test results.
Testing.com is an award-winning patient education website offering information on laboratory tests. The content on the site, which has been reviewed by laboratory scientists and other medical professionals, provides general explanations of what results might mean for each test listed on the site, such as what a high or low value might suggest to your healthcare practitioner about your health or medical condition.
The reference ranges for your tests can be found on your laboratory report. They are typically found to the right of your results.
If you do not have your lab report, consult your healthcare provider or the laboratory that performed the test(s) to obtain the reference range.
Laboratory test results are not meaningful by themselves. Their meaning comes from comparison to reference ranges. Reference ranges are the values expected for a healthy person. They are sometimes called “normal” values. By comparing your test results with reference values, you and your healthcare provider can see if any of your test results fall outside the range of expected values. Values that are outside expected ranges can provide clues to help identify possible conditions or diseases.
While accuracy of laboratory testing has significantly evolved over the past few decades, some lab-to-lab variability can occur due to differences in testing equipment, chemical reagents, and techniques. This is a reason why so few reference ranges are provided on this site. It is important to know that you must use the range supplied by the laboratory that performed your test to evaluate whether your results are “within normal limits.”
For more information, please read the article Reference Ranges and What They Mean.
What is being tested?
Porphyrins are a group of compounds defined by their chemical structure. These compounds are by-products of heme synthesis and are normally present at low levels in blood and other body fluids. Porphyrin tests measure porphyrins and their precursors in urine, blood, and/or stool.
Heme is an iron-containing pigment that is a component of hemoglobin and a number of other proteins. It consists of an organic portion (protoporphyrin) bound to an iron atom. The synthesis of heme is a step-by-step process that requires the sequential action of eight different enzymes. If there is a deficiency in one of these enzymes, the process is impeded and intermediate porphyrins such as uroporphyrin, coproporphyrin, and protoporphyrin build up in the body’s fluids and tissues. The precursors that accumulate depend on which enzyme is deficient, and they can exert toxic effects.
Porphyrin tests are used to help diagnose and monitor a group of disorders called porphyrias. There are seven types of porphyria, and each one is associated with a different enzyme deficiency. Most porphyrias are inherited, the result of a gene change (variant). Porphyrias may be classified according to the signs and symptoms of the disease as neurological, cutaneous, or both.
The porphyrias that cause neurological symptoms present with acute attacks lasting days or weeks. Signs and symptoms during the attack include abdominal pain, constipation, confusion, hallucinations, and/or seizures. There are four neurologic porphyrias: acute intermittent porphyria (AIP), variegate porphyria (VP), hereditary coproporphyria (HCP), and the very rare ALA dehydratase deficiency porphyria (ADP). Some cases of VP and HCP may also have skin-related symptoms.
The cutaneous porphyrias are associated with photosensitivity that causes redness, swelling, a burning sensation, blistering, skin thickening, hyperpigmentation, and/or scarring. There are three cutaneous porphyrias: porphyria cutanea tarda (PCT), erythropoietic protoporphyria (EPP), and congenital erythropoietic porphyria (CEP).
Experts have not yet reached agreement on whether all porphyrias are inherited. Porphyria cutanea tarda (PCT) may result from genetic or environmental factors such as exposure to certain chemicals or significant liver damage. This type of PCT is termed “acquired” or “sporadic.” In patients with acquired PCT, the disorder usually develops after age 30 and onset in childhood is rare.
To diagnose porphyrias, laboratories measure porphyrins and their precursors in urine, blood, and/or stool. Testing may include measurement of one or more of the following:
- Porphobilinogen (PBG), a porphyrin precursor, in urine
- Delta-aminolevulinic acid (ALA), another porphyrin precursor, in urine
- Porphyrins (uroporphyrin, coproporphyrin, and protoporphyrin) in urine, blood, or stool
Specialized laboratories may offer testing for one or more of the affected enzymes. The most commonly measured enzyme is porphobilinogen deaminase (PBG-D) in red blood cells, which tests for acute intermittent porphyria. A few laboratories offer genetic testing for specific gene variants that cause one of the porphyrias, but this type of testing is not widely available. If your health care practitioner strongly suspects a specific type of porphyria, a sample for genetic testing may be sent to a reference laboratory that performs that type of testing routinely.
Common Questions
View Sources
Sources Used in Current Review
2020 review performed by Grace R. Williams, PhD, Virginia Commonwealth University Health System, Assistant Professor, Division of Clinical Pathology, Toxicology Laboratory Director, Clinical Chemistry Laboratory Associate Director.
(April 14, 2020) NIH Genetic and Rare Diseases Information Center. Porphyria. Available online at https://rarediseases.info.nih.gov/diseases/10353/porphyria#diseaseOverviewSection. Accessed April 2020.
(April 14, 2020) American Porphyria Foundation Guidelines for Health Professionals: Emergency Room Guidelines for Acute Porphyrias. Available online at https://porphyriafoundation.org/for-healthcare-professionals/emergency-room-guidelines-for-acute-porphyrias/. Accessed April 2020.
(April 14, 2020) National Organization of Rare Diseases. Porphyria Cutanea Tarda. Available online at https://rarediseases.org/rare-diseases/porphyria-cutanea-tarda/. Accessed April 2020.
(April 14, 2020) Mayo Clinic Laboratories Test Catalog: Porphyria Acute Testing Algorithm. Available online at https://www.mayocliniclabs.com/it-mmfiles/Porphyria__Acute__Testing_Algorithm.pdf. Accessed April 2020.
(April 14, 2020) Mayo Clinic Laboratories Test Catalog: Porphyria Cutaneous Testing Algorithm. Available online at https://www.mayocliniclabs.com/it-mmfiles/Porphyria__Cutaneous__Testing_Algorithm.pdf. Accessed April 2020.
(April 14, 2020) NIH National Library of Medicine MedlinePlus. Porphyria. Available online at https://medlineplus.gov/ency/article/001208.htm. Accessed April 2020.
Rifai N, Horvath AR, Wittwer CT eds. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics, 6th Ed. Porphyrias and Porphyrins p. 776-799.
Sources Used in Previous Reviews
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AIP, HCP, VP, & ADP, Diagnosis.
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EPP.
http://www.porphyriafoundation.com/for_physicians/epp/epp02.html
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(© 2004). Six articles [see below]. ARUP’s Guide to Clinical Laboratory Testing. Available online through http://www.aruplab.com
Aminolevulinic Acid (ALA), Urine.
http://www.aruplab.com/guides/clt/tests/clt_al48.jsp#1141880
Porphobilinogen (PBG) Deaminase, Erythrocyte.
http://www.aruplab.com/guides/clt/tests/clt_146b.jsp#1144972
Porphobilinogen (PBG), Urine.
http://www.aruplab.com/guides/clt/tests/clt_147b.jsp#1144990
Porphyrins, Urine.
http://www.aruplab.com/guides/clt/tests/clt_150b.jsp#1145094
Porphyrins, Fecal.
http://www.aruplab.com/guides/clt/tests/clt_149b.jsp#1145074
Porphyrins, Blood and Serum.
http://www.aruplab.com/guides/clt/tests/clt_148b.jsp#1145040
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Pischik E, Kauppinen R. An update of clinical management of acute intermittent porphyria. Appl Clin Genet. 2015 Sep 1;8:201-14. Available online at http://www.ncbi.nlm.nih.gov/pubmed/26366103. Accessed May 2016.
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