Plasma porphyrins in the porphyrias.

BACKGROUND As an aid in the diagnosis and management of porphyria we have developed a method to fractionate and quantify plasma porphyrins and have evaluated its use in various porphyrias. METHODS We used HPLC with fluorometric detection to measure plasma concentrations of uroporphyrin I and III, heptacarboxyl III, hexacarboxyl III, pentacarboxyl III, and coproporphyrin I and III. We studied 245 healthy subjects, 32 patients with classical porphyria cutanea tarda (PCT), 12 patients with PCT of renal failure, 13 patients with renal failure, 8 patients with pseudoporphyria of renal failure, 3 patients with acute intermittent porphyria, 5 patients with variegate porphyria, 5 patients with hereditary coproporphyria, and 4 patients with erythropoietic protoporphyria. RESULTS Between-run CVs were 5.4-13%. The recoveries of porphyrins added to plasma were 71-114% except for protoporphyrin, which could not be reliably measured with this technique. Plasma porphyrin patterns clearly identified PCT, and its clinical sensitivity equaled that of urine porphyrin fractionation. The patterns also allowed differentiation of PCT of renal failure from pseudoporphyria of renal failure. CONCLUSIONS The assay of plasma porphyrins identifies patients with PCT and appears particularly useful for differentiating PCT of renal failure from pseudoporphyria of renal failure.