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Porphyrins - bloodDefinition Total porphyrin levels measure 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 amounts 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 show the levels of specific porphyrins. How the test is performed Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic. An elastic band is placed around the upper arm to apply pressure and cause the vein to swell 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. In infants or young children: 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. A bandage may be applied to the puncture site if there is any bleeding. The sample is then placed in ice and taken immediately to the laboratory. How to prepare for the test Fasting for 12 - 14 hours prior to this test is required. You may drink water right before the test. If your child is to have this test performed, it may be helpful to explain how the test will feel, and even demonstrate on a doll. Explain the reason for the test. Knowing the "how and why" may reduce the anxiety your child feels. 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 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 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:
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 Increased levels of coproporphyrins may indicate:
Increased protoporphyrin levels may indicate:
Increased uroporphyrin levels may indicate:
What the risks are Risks associated with having blood drawn are slight:
Special considerations Failure to comply with dietary restrictions prior to the test may alter and invalidate test results. 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. Illustrations
Page Content: Uroporphyrin levels; Protoporphyrin levels; Porphyrins - total; Coproporphyrin levels |
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