Phototherapy contraindicated in infants with which porphyria?

• A. Porphyria cutanea tarda
• B. G6PD deficiency
• C. Congenital erythropoietic porphyria
• D. HbH disease

Answer: (C)

Phototherapy uses blue light to transform unconjugated bilirubin into water-soluble forms that can be excreted. In certain porphyrias, especially congenital erythropoietic porphyria, porphyrins accumulate in the skin and are highly light-sensitive. When exposed to light, these porphyrins generate reactive oxygen species that cause tissue damage and severe photosensitivity. Because phototherapy would trigger this light-induced injury, it is contraindicated in infants with congenital erythropoietic porphyria.

Porphyria cutanea tarda is a photosensitive porphyria but typically presents later in life and is not the classic neonatal contraindication. G6PD deficiency is an enzymatic defect affecting red cell oxidative stress, not a porphyrin-based photosensitivity, so it does not constitute a contraindication to phototherapy. HbH disease is a hemoglobinopathy and likewise does not involve light-activated porphyrin accumulation, so it is not a reason to avoid phototherapy.