Bullous dermatoses in end-stage renal failure: Porphyria or pseudoporphyria?

Bullous dermatoses (BD) are well recognized in patients with end-stage rena l disease (ESRD), It is important to distinguish pseudoporphyria (porphyrin accumulation due to decreased clearance) from true porphyrias, particularl y those in which acute neurological attacks may occur. Investigation of the dialysis patient poses practical diagnostic difficulties because urinary p orphyrin profiles are not available. We describe a patient on continuous am bulatory peritoneal dialysis (CAPD) with several recognized causative facto rs for porphyria cutanea tarda (PCT). The patient presented with a blisteri ng photosensitive rash. We highlight the importance of investigating anuric patients with fractionation of both fecal and plasma porphyrins. Plasma po rphyrins were grossly elevated (345 nmol/L; reference range, <13), whereas plasma porphyrins in a control group of CAPD patients without blistering ra shes were only minimally elevated (mean, 23.9 nmol/L; SD, 11.0; n = 9). Fra ctionation of fecal porphyrins by high-performance liquid chromatography (H PLC) yielded a pattern typical of PCT. In addition to the contributory fact ors for PCT that were present, it is possible that porphyrin accumulation s econdary to renal failure played a role in the expression of her disease. P atients with ESRD presenting with ED require careful evaluation, including fractionation of fecal porphyrins. (C) 1999 by the National Kidney Foundati on, Inc.