Riboflavin Status in PUVA Patients

To the Editor.—  A recently developed method for controlling psoriasis vulgaris employs a phototoxic chemical, 8-methoxypsoralen and long-wave ultraviolet (UV) light in the A range of 320 to 390 nm.¹ The method is called PUVA (for psoralen and UVA). Equipment for delivering the UVA provides UV light with peak intensity at 360 nm but also emits considerable light of longer wavelengths.The vitamin riboflavin is degraded by light in the 425-nm range.² Riboflavin deficiency has been caused in neonates treated with phototherapy (415 to 465 nm) for hyperbilirubinemia.² We wondered whether PUVA therapy might also result in riboflavin deficiency.Ten patients with psoriasis who were receiving PUVA therapy had their riboflavin levels assessed by the method of erythrocyte glutathione reductase activity.³ These patients were receiving 40 mg of 8-methoxypsoralen orally, followed after two hours by whole-body irradiation with UVA (along with the inevitable longer wavelengths of