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.