Ascorbic Acid Deficiency in Porphyria Cutanea Tarda
Porphyria cutanea tarda (POT), the most common form of porphyria, is manifested as skin photosensitivity caused by excess hepatic production of uroporphyrin and heptacarboxylporphyrin. In experimental animal models, ascorbic acid modulates chemically induced uroporphyrin accumulation, The purpose of this study was to determine whether ascorbic acid is decreased in the plasma of patients with PCT. Plasma was obtained after an overnight fast from 21 PCT patients, 16 of whom were infected with hepatitis C virus (HCV), and from a separate group of 9 patients with HCV infection but not PCT, Thirteen PCT patients were studied when they had active disease and 8 after treatment-induced remission. Plasma ascorbic acid was low (less than 23 mu mol/L) in 11 (85%) of the 13 untreated PCT patients and deficient (less than 11 mu mol/L) in 8 (62%), Two patients with normal ascorbic acid levels (45 and 62 mu mmol/L) had consumed multivitamins. In 2 patients with deficient ascorbic acid, plasma levels returned to normal after phlebotomy treatment, Of the 8 patients studied during remission, 4 had normal ascorbic acid values and 4 were deficient (5 to 8 mu mol/L). Plasma ascorbic acid values were normal for all patients who had HCV but no PCT, These data suggest that plasma ascorbic acid concentrations are commonly low in POT, but this decrease is unrelated to HCV infection, Ascorbic acid deficiency may be one of the factors that contributes to the pathogenesis of PCT.
Author: SINCLAIR PR, VET ADM MED CTR, WHITE RIVER JCT, VT 05009; Source: JOURNAL OF LABORATORY AND CLINICAL MEDICINE 1997 AUG;130(2):197-201