DRY SKIN (XEROSIS) IN PATIENTS UNDERGOING MAINTENANCE HEMODIALYSIS - THE ROLE OF DECREASED SWEATING OF THE ECCRINE SWEAT GLAND

The aetiology and the pathophysiological mechanisms underlying the dev elopment of dry skin in uraemia are still unclear, but the hydration s tatus of stratum corneum clearly influences the appearance of skin. Th e xerotic skin texture is often referred to as 'dry skin' and has been suggested as a cause of uraemic pruritus. To understand the aetiology of dry skin in uraemia we measured the status of skill surface hydrat ion of uraemic patients with the corneometer and skin surface hydromet er, the functional capacity and the urea concentration of stratum corn eum and the response of eccrine sweat gland to sudorific agent (0.05% pilocarpine HCL) in 18 age-matched haemodialysis patients and 10 healt hy volunteers. We also performed the water sorption-desorption test to uraemic and control subjects after application of urea in various con centrations. Uraemic patient's skin showed decreased water content com pared to control subjects. However, we found no correlation between dr y skin and pruritus. Although the urea concentration of the horny laye r in uraemic patients was elevated compared to control subjects (28.2 mu g/cm(2) vs 5.04 mu g/cm(2), P < 0.05), its moisturizing effect to r elieve pruritus is questionable because its artificial application rev ealed no improvement of the functional capacity of horny layer in conc entration 5 times higher than the physiological concentration. Uraemic patients showed decreased sweating response to sudorific agent. In co nclusion, the functional abnormalities of eccrine sweat glands may be account for dry skin in uraemic patients at least in part, but there i s no correlation between xerosis and pruritus.