Haem synthesis

Haem is a multi-ring (porphyrin) structure that chelates an iron ion. It is a key component of cytochromes and haemoglobin.

Porphyria

Porphyria Cutanea Tarda (PCT)

• most common hepatic porphyria
• more common in men; after age of 40
• sporadic cases are due to chronic liver disease, usually alcohol-related, Hepatitis C, iron overload (hemochromatosis), HIV and sometimes estrogen use
• reduced uroporphyrinogen decarboxylase activity

Features

• photosensitive skin rash and bullae
• (hypersensitivity of the skin to abnormal porphyrias when they are exposed to light)
• occur as fragile, nonhealing blisters, leading to hyperpigmentation of the skin in general and hypertrichosis of the face
• Diabetes is found in 25% of patients

Dx

• the most accurate test = increased uroporphyrins in a 24-hr urine collection

Tx -

1. treat underlying liver disease (stop alcohol, discontinue estrogens),
2. barrier sun protection