What are labs of PCT?

• Urinary porphyrin levels are abnormally high in PCT patients, with several hundred to several thousand micrograms excreted in a 24-hour period • The excess porphyrin pigment is often grossly evident in visible light and yields a pink fluorescence under Wood lamp (black light) radiation • Skin biopsy findings by light microscopy DIF may be consistent with a diagnosis of PCT but are not unequivocally diagnostic • DIF can help differentiate PCT from immunobullous diseases with dermoepidermal junction cleavage (epidermolysis bullosa acquisita, lupus erythematosus) in which the perivascular Ig deposition found in PCT is not observed