Microsoft Word - NEF485BF

P. Bindi, Service de Néphrologie, (Prof. Mignon), Hôpital Tenon, 4, rue de la Chine, F-75020 Paris (France) Dear Sir, Aluminum (Al) overload is still a worrying problem in long-term dialysis patients. Data are lacking on Al accumulation in the skin of such patients and its relationship to bone overload. Skin biopsies would yet be a noninva-sive method to assess Al intoxication. In their study, Ichimaru and Horie [1] found large amounts of Al in the skin of dialyzed patients with an energy-dispersive X-ray spectrometer. However, a number of artefacts may be due to the use of a spectrometer of low resolution, and Al was surprisingly found in all structures of the skin. Skin specimens were harvested from the buttocks, using the punch biopsy technique, of 3 hemodialyzed (60, 96 and 244 months respectively) patients, 1 end-stage renal failure, nondialyzed patient, and 1 patient with normal renal function. Tape stripping of the skin was performed just before harvesting in order to clear out the stratum corneum contaminated by aluminosilicate deposits. The skin Al content was measured by electrothermal atomic absorption spectrometry. Another fragment was fixed in glutaraldehyde, postosmicated, and embedded in Epon. This fragment was studied by two mic-roanalytical methods: (1) electron proble X-ray analysis using an instrument equipped with a four wavelengh dispersive X-ray spectrometer of high resolution and with a transmission electron microscope which allows the distinction between cell accumulation and contamination by atmospheric dusts and (2) analytical electron microspcopy [2], a highly sensitive method for the detection of Al (about 1,000-fold more sensitive than X-ray analysis). Despite tape stripping, deep stratum corneum was still present in all biopsied fragments. Considerable variation in biochemical Al skin content was found from one patient to another (table 1). Values were greatly higher than in organs where Al is known to accumulate, i.e., liver or parathyroid glands. There was no correlation between skin Al content and dialysis duration, nor with bone intoxication: a patient with aplastic bone disease and Table 1. Al content in skin and plasma with biochemical measurements related to bone Al staining and dialysis duration