Porphyrins are increased in bone marrow, erythrocytes, plasma, urine, and feces in a characteristic pattern, usually to levels much higher than those in other porphyrias. I are the predominant porphyrins in urine, plasma, and erythrocytes, and coproporphyrin I is the predominant porphyrin in feces. Sometimes erythrocytes contain large amounts of protoporphyrin, as in other homozygous porphyrias. Demonstration of deficient uroporphyrinogen cosynthase activity confirms the diagnosis. ALA and PBG are not increased.
Hepatoerythropoietic porphyria is similar clinically, but porphyrin patterns are different.
Treatments for CEP are not very effective. Therefore, avoiding sunlight and wearing protective clothing are important. Several manufacturers specialize in protective fabrics and clothing for sun-sensitive people. More recently NASA has developed a special space suit for CEP patients to wear. Heterozygotes can be detected in affected families, and diagnosis in utero is possible.