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Alternative names Return to top
Uroporphyrin levels; Protoporphyrin levels; Porphyrins - total; Coproporphyrin levelsDefinition Return to top
This test measures total red blood cell porphyrins.
Porphyrins are pigments found in animals and plants. They are involved in the formation of many important substances in the body including hemoglobin, which carries oxygen in the blood.
Coproporphyrin, protoporphyrin, and uroporphyrin are three porphyrins related to red blood cells, which can normally be measured in small amount in the human blood stream. Protoporphyrin is normally found in highest quantity and thus this test is also known as the PROTO test. Additional tests are needed to know the levels of specific porphyrins.
How the test is performed Return to top
Blood is drawn from a vein, usually on the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and an elastic band is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the band to fill with blood.
A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the band is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.
For an infant or young child, the area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding.
How to prepare for the test Return to top
Fasting for 12 to 14 hours prior to this test is required. You may drink water right before the test.How the test will feel Return to top
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.Why the test is performed Return to top
This test is used to diagnose porphyrin disorders involving red blood cells. In combination with other tests, this test is useful for diagnosing disorders such as lead poisoning and some neurologic and skin disorders.Normal Values Return to top
This test specifically measures total porphyrin levels, but reference values (i.e., range of values seen in a group of "healthy" people) for the individual components are also included:Note: mcg/dl = micrograms per deciliter
It is important to recognize that these reference ranges will vary between different laboratories depending upon the way the test is performed. Individual results must therefore be interpreted accordingly.What abnormal results mean Return to top
Increased levels of coproporphyrins may indicate:What the risks are Return to top
Risks associated with having blood drawn are slight:Special considerations Return to top
Failure to comply with dietary restrictions prior to the test may alter and invalidate test results.
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Page last updated: 28 October 2004 |