Pitfalls in Erythrocyte Protoporphyrin Measurement for Diagnosis and Monitoring of Protoporphyrias

“…Severity is highly variable, however, most patients are able to tolerate <30 minutes of sun exposure. 5 With chronic exposure, the involved skin may become hyperkeratotic. 3,8 Anemia is seen in ~40% of patients and 25% of patients will develop abnormal serum aminotransferases.…”

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confidence: 99%

Diagnostic Delay in Erythropoietic Protoporphyria

Lala

Naik

Balwani

2018

The Journal of Pediatrics

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“…While the ultimate diagnosis requires genetic testing, XLP can be distinguished from EPP by a much higher percent of zinc‐complexed protoporphyrin on whole blood studies. In EPP, less than 15% of total protoporphyrin is zinc protoporphyrin, while in XLP zinc protoporphyrin is 15%‐50% of the total …”

Section: Discussionmentioning

confidence: 99%

Erythema and blistering after sun exposure in a 12‐year‐old boy

Collier

Danford

Boyd

2019

Pediatric Dermatology

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A previously healthy 12-year-old boy presented to the emergency room with severe pain, erythema, and blistering on his dorsal hands and feet after prolonged sun exposure 3 days prior. The caregiver reported that since the age of 4, the patient has had several episodes of rash after sun exposure. In total, he has had 4 to 5 episodes, with the current outbreak being the most severe. He reported that he does not always get a rash after sun exposure, but it is worsened by sunscreens. The family reported that he had previously been diagnosed with a "sunscreen allergy" and thus had not been using sun protection this summer. Physical examination was significant for well-defined erythematous to violaceous patches and macules studded with vesicles on the dorsal hands and dorsal feet. There were well-demarcated areas of sparing at sites of a previous bandage sandal strap (Figures 1 and 2). The bilateral malar cheeks and nasal bridge demonstrated erythematous patches. A 4-mm punch biopsy was obtained from the right dorsal hand (Figure 3).

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“…Specialized porphyria laboratories report levels of total erythrocyte, metal-free, and zinc-protoporphyrin. 113 The proportion of zinc-protoporphyrin to metal-free protoporphyrin is significantly higher in patients with XLP (>25%) than in those with EPP (up to 15%). Notably, urinary porphyrins are normal in protoporphyrias.…”

Section: Diagnosismentioning

confidence: 95%

Clinical Guide and Update on Porphyrias

Stölzel¹,

Doss²,

Schuppan³

2019

Gastroenterology

115

158

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Physicians should be aware of porphyrias, which could be responsible for unexplained gastrointestinal, neurologic, or skin disorders. Despite their relative rarity and complexity, most porphyrias can be easily defined and diagnosed. They are caused by well-characterized enzyme defects in the complex heme biosynthetic pathway and are divided into categories of acute vs non-acute or hepatic vs erythropoietic porphyrias. Acute hepatic porphyrias (acute intermittent porphyria, variegate porphyria, hereditary coproporphyria, and aminolevulinic acid dehydratase deficient porphyria) manifest in attacks and are characterized by overproduction of porphyrin precursors, producing often serious abdominal, psychiatric, neurologic, or cardiovascular symptoms. Patients with variegate porphyria and hereditary coproporphyria can present with skin photosensitivity. Diagnosis relies on measurement of increased urinary 5-aminolevulinic acid (in patients with aminolevulinic acid dehydratase deficient porphyria) or increased 5-aminolevulinic acid and porphobilinogen (in patients with other acute porphyrias). Management of attacks requires intensive care, strict avoidance of porphyrinogenic drugs and other precipitating factors, caloric support, and often heme therapy. The non-acute porphyrias are porphyria cutanea tarda, erythropoietic protoporphyria, X-linked protoporphyria, and the rare congenital erythropoietic porphyria. They lead to the accumulation of porphyrins that cause skin photosensitivity and occasionally severe liver damage. Secondary elevated urinary or blood porphyrins can occur in patients without porphyria, for example, in liver diseases, or iron deficiency. Increases in porphyrin precursors and porphyrins are also found in patients with lead intoxication. Patients with porphyria cutanea tarda benefit from iron depletion, hydroxychloroquine therapy, and, if applicable, elimination of the hepatitis C virus. An a-melanocytestimulating hormone analogue can reduce sunlight sensitivity in patients with erythropoietic protoporphyria or Xlinked protoporphyria. Strategies to address dysregulated or dysfunctional steps within the heme biosynthetic pathway are in development.

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Pitfalls in Erythrocyte Protoporphyrin Measurement for Diagnosis and Monitoring of Protoporphyrias

Cited by 28 publications

References 17 publications

Diagnostic Delay in Erythropoietic Protoporphyria

Diagnostic Delay in Erythropoietic Protoporphyria

Erythema and blistering after sun exposure in a 12‐year‐old boy

Clinical Guide and Update on Porphyrias

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