Dry skin (xerosis) in patients undergoing maintenance haemodialysis: the role of decreased sweating of the eccrine sweat gland

The aetiology and the pathophysiological mechanisms underlyingthe development of dry skin in uraemia are still unclear, butthe hydration status of stratum corneum clearly influences theappearance of skin. The xerotic skin texture is often referredto as ‘dry skin’ and has been suggested as a causeof uraemic pruritus. To understand the aetiology of dry skinin uraemia we measured the status of skin surface hydrationof uraemic patients with the corneometer and skin surface hydrometer,the functional capacity and the urea concentration of stratumcorneum and the response of eccrine sweat gland to sudorificagent (0.05% pilocarpine HCL) in 18 age-matched haemodialysispatients and 10 healthy volunteers. We also performed the watersorption-desorption test to uraemic and control subjects afterapplication of urea in various concentrations. Uraemic patient'sskin showed decreased water content compared to control subjects.However, we found no correlation between dry skin and pruritus.Although the urea concentration of the horny layer in uraemicpatients was elevated compared to control subjects (28.2 ug/cm2vs 5.04 ug/cm2, P<0.05), its moisturizing effect to relievepruritus is questionable because its artificial applicationrevealed no improvement of the functional capacity of hornylayer in concentration 5 times higher than the physiologicalconcentration. Uraemic patients showed decreased sweating responseto sudorific agent. In conclusion, the functional abnormalitiesof eccrine sweat glands may be account for dry skin in uraemicpatients at least in part, but there is no correlation betweenxerosis and pruritus.