The evaluation of porphyria cutanea tarda begins with a history and physical examination.

Physical findings of porphyria cutanea tarda may include:

• Red rash:
• Occurs on skin exposed to the sun
• Blisters:
• Form on the hands and arms, or the face
• Darkened skin on the face, hands, neck and back
• Increased hair growth on the face
• Firm, yellow skin:
• Located on the trunk and back of the neck
• Dark urine

Testing is necessary to confirm the diagnosis of porphyria cutanea tarda.

Tests that may be used to evaluate porphyria cutanea tarda include:

• Blood porphyrin levels
• Blood assays for enzymes involved in the production of the chemical heme
• Skin biopsy
• Urine porphyrins
• Urine porphobilinogen
• Kidney profile