Abnormal levels of urinary porphyrins, oxidized metabolites of heme biosynthesis, are associated with genetic disorders, metabolic disturbances and diseases, anemias, oxidative stress, and high-level exposure to toxic chemicals or metals. Specific urine porphyrin profiles are associated with high-level exposure to mercury, arsenic, lead and some chemicals and drugs. Urinary porphyrins are readily excreted in excess when porphyrinogens accumulate as a result of inhibition of specific enzymes in the heme biosynthetic pathway. Heme is required for oxygen binding, transport and utilization, cytochromes, and electron transport in mitochondria. The high rate of production of heme facilitates the use of urinary porphyrins as early and sensitive biomarkers of disorders in heme production, which has long been associated with genetic disorders, metabolic disturbances and diseases, nutritional status, oxidative stress and high-level exposure to toxic chemicals or metals. Analytes Tested: Copro I-Copro III ratio Coproporphyrin I Coproporphyrin III Heptacarboxyporphyrin Hexacarboxyporphyrin Pentacarboxyporphyrin Precoproporphyrin Peak I Precoproporphyrin Peak II Precoproporphyrin Peak III Precoproporphyrin Uro Ratio Total Porphyrins Total Precoproporphyrin Peak IIII Uroporphyrins