Porphyrins pathway is involved in heme synthesis, which is the red pigment that gives red blood cells their distinctive color. Disturbance in one of the enzymes of the pathway will lead to accumulation of the intermediate molecules.
Porphyria cutaneous tarda (PCT) is the most common human porphyria caused by hepatic deficiency of uroporphyrinogen decarboxylase (UROD). Clinical picture is limited to cutaneous manifestations.
In 1⁄3 of patients, familial autosomal dominant UROD mutation is the underlying cause of the disease. However an underlying acquired cause could be the culprit as well.
Acquired causes:
● Presence of iron overload ● Alcohol abuse
● Infections (HIV and HCV) ● Smoking
PCT can occur at any age but the peak incidence is around 5th or 6th decade. It also occurs in both genders but a slight predilection for men.
It can present as increased photosensitivity due to the porphyrin associated with skin fragility and blistering in sun-exposed areas, i.e the hands and the forearms. Most notably the color of the urine becomes darker, with a reddish hue.

Treatment of the underlying problems yields the good results. Phlebotomy is the main treatment for PCT, it can effectively treat the problem. If the patient is geriatric or anemic, the use of hydroxychloroquine is advisable to excrete porphyrins more easily.

Written by: Naif Alalshaikh, medical student

References:

“Porphyria Cutanea Tarda.” DermNet, https://dermnetnz.org/topics/porphyria-cutanea-tarda.

Singal, Ashwani K. “Porphyria Cutanea Tarda: Recent Update.” Molecular Genetics and Metabolism, vol. 128, no. 3, 2019, pp. 271–281., https://doi.org/10.1016/j.ymgme.2019.01.004.