[Chronic hemodialysis-related porphyria/pseudoporphyria]

Abstract

In a considerable proportion of the patients with chronic renal failure, skin changes resembling porphyria cutanea tarda (PCT) develop some months to years after the onset of maintenance hemodialysis. This can be either real PCT, or secondary PCT, or PCT-like bullous dermatosis. In a minor proportion, real PCT can be diagnosed. In such cases, elevated total porphyrin levels with a predominance of uro- (I > III) and heptacarboxyl porphyrins (III > I) can be measured in the plasma (also in the urine, if not anuric), and fecal (perhaps urinary as well) isocoproporphyrin can be detected. The activity of the hepatic uroporphyrinogen decarboxylase (UD) is decreased in every type of PCT; in PCT-II, also that of the erythrocyte UD. In a higher proportion, secondary PCT (pseudo-PCT) develops. In this group, porphyrins are accumulated in the plasma due to the unsatisfactory renal function. Uro and hepta are the dominant fractions here as well, but alteration in the ratio of the uro isomers or the presence of isocoproporphyrin can not be expected. The UD activity is probably normal in every tissue. In 1% to 18% of the cases, PCT-like bullous dermatoses develop, but porphyrins are at normal levels in all compartments. The phototoxic agent here is other than porphyrin (e.g. nalidixic acid, furosemide, tetracycline, etc., or unknown). The authors review the knowledge on chronic hemodialysis-related PCT or the PCT-like bullous dermatoses: development of the above-mentioned conditions, clinical and morphological and biochemical features, difficulties in diagnosis, or the possibilities in therapy.