The use of a metal halide lamp for the induction of photohemolysis in porphyria.

Abstract

ABSTRACTSeveral light sources, including sunlight, xenon lamps, fluorescent lamps, mercury lamps and carbon arc lamps, have been used to provoke skin changes for phototests in patients with porphyrias, or to induce experimental hemolysis of porphyrins for research. The metal halide lamp has a strong emission range between 400 nm and 450 nm, and a relatively low emission range in the ultraviolet region. For this reason, we explored the possibility that this lamp could be used to induce photohemolysis caused by hematoporphyrin (HP) and the radiation of light. Twenty to forty μg of HP‐HCl was added to 25 ml of a normal red blood cell suspension. The flask containing this red blood cell suspension was then irradiated using a metal halide lamp with 3.6 to 10.8 J/cm2 of light. All of the irradiated red blood cell suspension was hemolyzed, but the non‐irradiated control showed very little hemolysis.Compared to natural sunlight, the energy emitted by the metal halide lamp is small. Therefore, a longer exposure from the metal halide lamp is required to obtain an amount of energy equivalent to sunlight. This type of light source covers a wide area for irradiation. From these results, we can speculate that a metal halide lamp source is of value when used experimentally to produce the chronic skin changes of porphyria.