Porphyria (Cutaneous) Testing Algorithm* Symptom: Skin manifestations restricted to sun-exposed areas Possible cutaneous porphyria: ■ Porphyria cutanea tarda (PCT) Symptoms: ■ ■ Edema Erythropoietic protoporphyria (EPP) PPFE / Protoporphyrins, ■ a ■ Sun-induced erythema Variegate porphyria (VP) Fractionation, Whole Blood ■ Hereditary coproporphyria (HCP)b ■ Acute painful photodermatitis ■ Congenital erythropoietic porphyria (CEP) ■ Urticaria ■ X-linked dominant protoporphyria (XLDPP) Normal Increased zinc Increased free Increased free and Symptoms: protoporphyrin protoporphyrin zinc protoporphyrins ■ Blistering lesions or bullae (>40% zinc ■ Skin fragility protoporphyrin) ■ Scarring Excludes EPP Consider: ■ EPP ■ Hyper/hypopigmentation ■ Iron de ciency anemia ■ Family studies ■ Possible hypertrichosis If clinically indicated ■ Heavy metal may be warranted intoxication Suspicious of XLDPP ■ Anemia of chronic Excludes Normal PQNRU / Porphyrins, Quantitative, disease FECHZ / Ferrochelatase PCT and CEP Random, Urine (includes PBG) (FECH) Gene, Full Gene Analysis If clinically Increased coproporphyrin Increased uroporphyrin Increased uroporphyrin and indicated and/or PBG and uroporphyrin and coproporphyrin heptacarboxylporphyrin Mutation No mutation indentified found FQPPS / Porphyrins, Feces UPGC / Uroporphyrinogen III Synthase UPGD / Uroporphyrinogen Confirms EPP (Co-Synthase) (UPG III S), Erythrocytes Decarboxylase (UPG D), Whole Blood Increased Increased coproporphyrin III/I coproporphyrin Normal Decreased Normal Decreased Normal ratio (<10) and III/I ratio (>10) and protoporphyrin coproporphyrin III a. 80% of patients with VP have Excludes Confirms ■ ■ Excludes PCT type II Excludes PCT type II cutaneous symptoms VP and HCP CEP CEP ■ Family studies ■ Does not exclude PCT type b. 20% of patients with HCP have ■ VP ■ HCP may be warranted I (sporadic) or PCT type IIIc cutaneous symptoms ■ Family studies ■ Family studies c. Erythrocyte uroporphyrinogen may be warranted may be warranted decarboxylase is normal in PCT types I and III PPOXZ / PPOX Gene, CPOXZ / CPOX Gene, Full Gene Analysis Full Gene Analysis Interpretive report provided for all tests in this algorithm © Mayo Foundation for Medical Education and Research (MFMER). All rights reserved. 11/2018.