Porphyrins are pigments found in both animal and plant life.
Coproporphyrin, protoporphyrin, and uroporphyrin are three porphyrins related to red blood cells that can normally be measured in small amount in the human blood stream. Additional tests must be performed to know the levels of specific porphyrins. A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the tourniquet 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 .