Chapter 49 - Porphyrias Flashcards Preview

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Flashcards in Chapter 49 - Porphyrias Deck (13):

How many types of porphyria are currently known?



True or false: in porphyrias, cutaneous symptoms affect the sun-exposed areas only.



Are all eight types of described porphyrias inherited?

No; porphyria cutanea tarda can be either acquired (type I) or inherited (type II)


List the four non-acute porphyrias.

Porphyria cutanea tarda (PCT), erythropoietic protoporphyria (EPP), congenital erythropoietic porphyria (CEP), and hepatoerythropoietic porphyria


How can natural light and Wood's light (a UVA light) be used to help diagnose PCT?

Urine from a PCT patient will turn red-brown after exposure to natural light after several hours and will then also fluoresce pink under UVA light (Wood's light)


What are the subtypes of acute and non-acute porphyrias?

Acute - acute intermittent, variegate, hereditary coproporphyria, ALA-D deficiency. Non-acute - PCT, erythropoietic protoporphyria, congenital erythropoietic, hepatoerythropoietic. Only acute intermittent and ALA-D deficiency have no cutaenous findings.


What is believed to cause life threatening acute neurologic attacks in acute intermittent and ALA-D defieincy porphyria?

Accumulation of porphyrin precursors ALA and porphobilinogen, which are excreted in large amounts by the liver and is very neurotoxic


What enzyme is affected in PCT?

Uroporphyrinogen decarboxylase


What is the difference between type I and II PCT?

Type 1 is acquired and the enzyme deficiency is expressed only in the liver. Type II is hereditary and enzyme deficiency is expressed in all tissues


What are some triggering factors for PCT?

EtOH, estrogens, polychlorinated hydrocarbons, hemodialysis, iron, mutations of HFE gene/hemochromatosis, viral infections (Hep C, HIV). There is a higher risk for PCT patients to develop hepatocellular carcinoma


What are some causes of pseudoporphyria?

CRD, hemodialysis, medicaions (NSAIDs, furosemide, tetracycline, retinoids), tanning beds


What is the treatment for PCT and other non-acute porphryias?

Supportive (avoid UVR, sun protective clothing, sunscreen especially titanium dioxide and zinc oxide), avoid EtOH, estrogen therapy, control iron overload with phlebotomy, antimalarials (except in those with homozygous C282Y). For EPP, beta-carotene, blood transfusions, deferoxamine/deferasirox, bone marrow/hematopoietic stem cell transplant. No specific treatment options for hepatoerythropoietic porphyria


What is the treatment for acute porphyric attacks?

Remove precipitating factors, symptomatic treatment, IV heme preparations (heme arginate or hematin). +/- ICU admission. Monitor. Avoid antimalarials and phlebotomy