Long-standing changes in the urinary profile of porphyrin isomers after clinical remission of porphyria cutanea tarda.

Patients with overt porphyria cutanea tarda (PCT) show a distinctive and abnormal urinary profile of porphyrin excretion. It is not known, however, whether clinical remission of the disease produces complete normalization of this profile. We selected 46 patients, previously diagnosed with PCT, who after treatment presented normal levels of total porphyrins in urine (< 35 nmol/mmol creatinine). We analyzed their urine specimens by hplc to identify and quantify the various porphyrins and we compared the urinary porphyrin profiles to those of 40 healthy volunteers. While healthy volunteers gave a pattern dominated by excretion of coproporphyrin III, 80% of the PCT patients in clinical remission showed the characteristic profile of PCT, with decreased coproporphyrin-to-uroporphyrin ratio and/or inversion of the normal coproporphyrin III-to-coproporphyrin I ratio. Detection of uroporphyrin III and heptacarboxyl III intermediates was significantly more common among the patients than the controls (p < 0.05). This study shows that PCT patients demonstrate persistent changes in urinary porphyrin profiles during clinical remission, even when total urinary porphyrin excretion has fallen to the normal range.