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Protoporphyrin IX in the skin measured noninvasively predicts photosensitivity in patients with erythropoietic protoporphyria
Author(s) -
Heerfordt I.M.,
Wulf H.C.
Publication year - 2016
Publication title -
british journal of dermatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.304
H-Index - 179
eISSN - 1365-2133
pISSN - 0007-0963
DOI - 10.1111/bjd.15050
Subject(s) - erythropoietic protoporphyria , protoporphyrin ix , erythema , photobleaching , photodynamic therapy , protoporphyrin , medicine , dermatology , photosensitivity , pathology , chemistry , fluorescence , materials science , porphyrin , optics , photochemistry , physics , organic chemistry , optoelectronics
Summary Background Erythropoietic protoporphyria ( EPP ) is a rare genetic disease that causes severe sensitivity to visible light as a result of protoporphyrin IX (Pp IX ) accumulation in the skin. Objectives To establish a noninvasive method to measure Pp IX in the skin of patients with EPP and to investigate how skin Pp IX relates to erythrocyte Pp IX and photosensitivity. Methods Skin Pp IX was measured in 25 patients with EPP by calculating the difference in Pp IX fluorescence before and after complete photobleaching of Pp IX using controlled illumination. The patients reported symptoms during the illumination and skin erythema was measured before and after illumination. Confirmation of the presence of Pp IX was obtained in seven patients by measuring the in vivo fluorescence emission spectrum. This method was used to examine skin Pp IX during the hours after an illumination in seven patients. Results We established a noninvasive method to measure skin Pp IX based on measurements of Pp IX fluorescence before and after complete Pp IX photobleaching. The patients had an average skin Pp IX of 2·0 units and skin emission spectra confirmed the presence of skin Pp IX (peak emission 632 nm). Skin Pp IX was associated with erythrocyte Pp IX ( P = 0·002, R 2 = 0·34), skin erythema ( P = 0·001, R 2 = 0·47) and symptoms during illumination. Furthermore, skin Pp IX increased during the hours after illumination. Conclusions We have developed a noninvasive method to measure skin Pp IX in patients with EPP . Skin Pp IX is dependent on erythrocyte Pp IX and exposure of the skin to light. This method can be used for objective monitoring of treatment effect.