[Quantitative measurement of induced skin reddening using optical reflection spectroscopy--methodology and clinical application].

Optical reflection spectroscopy is a simple and quick method for the quantification of colour intensity, and is thus suitable for the determination of changes in skin reddening (erythema) due to local vasodilatation. To quantify the time course of this erythema, the oxyhaemoglobin absorption double peak with maxima at 542 and 577 nm is an appropriate parameter. A compact handheld optical spectrometer makes the technique applicable to clinical use, an example being the niacin patch test described herein. This noninvasive test provides information about the cell membrane metabolism via the skin flush induced by niacin (vitamin B3) and mediated by prostaglandin. The aim of this study was to adapt optical reflection spectroscopy to the requirements of the clinical niacin patch test. To that end, we investigated 60 healthy volunteers. Analysis of the spectroscopic data with regard to physiological covariables of niacin sensitivity revealed faster and more intense erythema in females--a gender effect that to our knowledge has not previously been reported. In the light of these results, the findings of other researchers based on semi-quantitative test methods should be reassessed, with consideration given to the gender effect.