High levels of urinary porphyrins in the urine are due to porphyria. Porphyria is a disorder of porphyrin metabolism characterized by increased excretion of porphyrins and porphyrin precursors in the urine and feces. Porphyria is a congenital disorder caused primarily by a deficiency of various enzymes related to heme synthesis and has a family history of occurrence. What are the causes of high urinary porphyrins in the urine? 1. Acute intermittent hematoporphyria is more common and is an autosomal dominant disease caused by a deficiency of PBG deaminase (uroporphyrinogen synthase). This defect reduces the conversion of PBG to uroporphyrinogen III in the liver, and the resulting impaired synthesis of heme causes the enhanced action of ALA synthase, resulting in increased synthesis of ALA and PBG and increased excretion from the urine. 2. Late-onset cutaneous hematoporphyria is the most common hematoporphyria, which is caused by a deficiency of uroporphyrinogen decarboxylase in the liver. It is autosomal dominant. Cases are sporadically distributed, with more males than females, and most patients have no family history. Some individuals have a biochemical defect of reduced enzymatic activity of uroporphyrinogen decarboxylase, but urinary excretion of uroporphyrins is not necessarily increased and clinically significant symptoms are not always present. The synergistic effects of genetic defects and acquired factors such as alcoholism, intrahepatic iron overload, liver damage, and female hormones further diminish the activity of uroporphyrin decarboxylase or stimulate the formation of ALA, resulting in a marked increase in the formation of uroporphyrins, leading to the development of late-onset cutaneous porphyria. 3, mixed porphyria is a disease caused by the reduction of protoporphyrinogenic oxidase and heme synthetase, which is inherited by autosomal dominant, and both sexes can get the disease. 4, hereditary fecal porphyria is a rare porphyria. It is an autosomal dominant disease, caused by the deficiency of fecal porphyrinogen oxidase. Some patients have photosensitive skin damage, and its clinical manifestations are similar to those of acute intermittent porphyrias. Although large amounts of fecal porphyrins are excreted in the feces of patients with this disease, the level of protoporphyrin is generally low. During acute attacks, large amounts of uroporphyrins, fecal porphyrins, ALA, and PBG may be present in the urine, which may become normal during recovery.