You are in Medical Library . This test is most often performed when porphyria or other disorder that can cause abnormal urine porphyrins is suspected. The most important function of porphyrins is as components of heme.
Oxygen binds to the iron in the heme molecules.
Various kinds of porphyrins exist with the same basic structure, but with slightly different chemical appearance. The major biochemical pathway includes conversions from porphyrins to delta-ALA , then to PBG , then uroporphyrin, then coproporphyrin, then protoporphyrin, and finally into the end product, heme. Each step requires the presence of an enzyme . A 24-hour urine sample is needed. The health care provider will instruct you, if necessary, to discontinue drugs that may interfere with the test.