Porphyria cutanea tarda - Don't forget to look at the urine

Diagnosis of porphyria cutanea tarda is usually fairly straightforward beca use of the characteristic clinical findings. Blisters and erosions develop acutely on sun-exposed skin, sometimes accompanied by hypertrichosis, abnor mal pigmentation, and milia formation. Iron stores are usually elevated, an d liver transaminases and blood glucose levels are often above normal as we ll. Gross examination of the urine can provide a valuable clue, since urine of porphyria cutanea tarda patients is red to brown in natural light and p ink to red in fluorescent light. Biopsy of a bullous lesion is useful to ru le out other diseases. Confirmations of porphyria cutanea tarda requires measurement of porphyrin levels in a 24-hour urine collection. Once the diagnosis is confirmed, it a ppears reasonable to screen all patients with porphyria cutanea tarda for h epatitis C and possibly B, but especially those less than 30 years old who have high level transaminase levels. Therapeutic measures for porphyria cutanea tarda include avoidance of exace rbating factors, especially ultraviolet light, ethanol, and certain medicat ions. Phlebotomy or choloroquine therapy is reserved for patients in whom c onservative measures fail.