endocrine and metabolic disorders
Porphyria Cutanea Tarda
Diagnosis of Porphyria Cutanea Tarda
Elevated levels of plasma porphyrins, urinary uroporphyrin and heptacarboxyl porphyrin, and fecal isocoproporphyrin In otherwise healthy patients, fragile skin and blister formation suggest porphyria cutanea tarda. Differentiation from Acute Porphyrias (variegate porphyria [VP] and hereditary coproporphyria [HCP]) is important because in patients with VP and HCP, the erroneous prescription of porphyrogenic medications may trigger the severe neurovisceral symptoms of the acute porphyrias. Previous unexplained neurologic symptoms or abdominal pain may suggest an acute porphyria. A history of exposure to chemicals that can cause pseudoporphyria should be sought. Although all porphyrias that cause skin lesions are accompanied by elevated plasma porphyrins, elevated urinary uroporphyrin and heptacarboxyl porphyrin and fecal isocoproporphyrin indicate PCT. Urine levels of porphyrin precursor porphobilinogen (PBG) is normal in PCT. Urinary delta-aminolevulinic acidmay be slightly increased (< 3 times the upper limit of normal). Red blood cell activity of UROD is normal in type 1 and type 3 PCT but decreased (by ~50%) in type 2. All patients with PCT should be tested for Hepatitis C, Chronic and 1.Caballes FR, Sendi H, Bonkovsky HL: Hepatitis C, porphyria cutanea tarda and liver iron: an update.Liver Int32(6):880–893, 2012. doi:10.1111/j.1478-3231.2012.02794.x 2.Bonkovsky HL, Guo JT, Hou W, et al: Porphyrin and heme metabolism and the porphyrias.Compr Physiol3(1):365–401, 2013. doi:10.1002/cphy.c120006 