Imagine that seated in the waiting room of your office is a pale stranger wearing a flowing black cape. In a halting Slavic accent, he complains of an aversion to sunlight and claims that his condition temporarily improves with ingestion of exogenous blood. While your instinct may be to protect your neck and run for safety, perhaps as his physician the next best step is to perform a urinalysis and hematologic testing!
Porphyria refers to a group of disorders characterized by defects in the biosynthetic pathway of heme, an erythrocyte cofactor essential for oxygen transport. Manifestations of this disease occur secondary to the accumulation of intermediates called porphyrins, which can cause photomutilation in sun-exposed areas of the skin. It was not until the 1980s, however, that porphyrias were first postulated as the inspiration for the myth of vampirism.
Maranda EL, Heifetz R, Estes WA, Cortizo J, Shareef S, Jimenez JJ. Porphyria and Vampirism—A Myth, Sensationalized. JAMA Dermatol. 2016;152(9):975. doi:10.1001/jamadermatol.2015.6066