Plasma porphyrins were grossly elevated, and a 24-hour urine specimen collected in a dark container also showed remarkably elevated porphyrin levels. Some were several thousand times the normal limit: uroporphyrin (octacarboxyl porphyrin) 3,629 ug/dL (normal 0-24), heptacarboxyl porphyrin 2,208 ug/dL, hexacarboxyl porphyrin 57 ug/dL, pentacarboxyl porphyrin 223 ug/dL, and coproporphyria (tetracarboxyl porphyrin) 47 ug/dL.
Analysis of the data revealed that the porphyrin increase was predominantly accounted for by uroporphyrin and heptacarboxyl porphyrin. This is specifically seen in PCT, not in the other porphyrias, confirming the diagnosis.
Ms. H was cautioned to adhere strictly to sun protection using physical barriers and sunscreens with zinc oxide or titanium dioxide (standard sunscreens do not absorb radiation in the near-visible UVA range).
Careful wound care was required for the enlarging vesicles, some of which covered the entire dorsum of the fingers (Figure 2). The vesicle roof was punctured via sterile technique to relieve pressure and alleviate pain. It was then left intact, providing a natural barrier to trauma and infection.
Ms. H. was referred to a hematology clinic for phlebotomy treatment and to a hepatologist specializing in the porphyrias for consultation. Avoidance of triggers, including alcohol, tobacco, estrogen, and iron supplementation, was emphasized.
The porphyrias are a group of disorders, either familial or acquired, caused by a defect in the metabolic pathway of heme synthesis, leading to increased production of the porphyrins. PCT, the most common of the porphyrias, is classified as a hepatic porphyria because the primary defect is in the hepatic enzyme uroporphyrinogen decarboxylase.
When uroporphyrinogen decarboxylase activity fails, porphyrin by-products accumulate in the liver and spread to other organs. Decline of enzyme activity to approximately 25% of normal is necessary for clinical disease to be expressed. Water-soluble porphyrins are excreted in the urine, and the others are excreted in the feces. The enzyme system that catalyzes heme synthesis is inducible; medications that affect the cytochrome drug metabolizing system may precipitate or exacerbate the porphyrias.