Using hair as a diagnostic tool: X-ray fluorescence monitoring of the Zn content of hairs of patients under parenteral nutrition

X-ray fluorescence excited by synchrotron radiation is a very sensitive met hod, allowing the analysis of trace elements along a single human hair. Our results demonstrate the applicability of the method to patients under pare nteral nutrition, in order to validate an adequate supplementation of Zn. W e were able, by studying different successive segments of a single hair, to monitor the Zn concentration during the therapy. Whereas the usual techniq ues for human hair analysis yield a mean value of the Zn concentration, the analysis of a single hair revealed important fluctuations with time (along the hair), among the different hairs of the same person and among hairs fr om different persons.