Relationship between pruritus, transepidermal water loss, and biochemical markers of renal itch in haemodialysis patients

: The pathogenesis of pruritus in patients undergoing chronic haemodialysis is unknown. Dryness of the skin is common in uraemic patients, and a correlation between xerosis and pruritus has been reported. Transepidermal water loss (TEWL) is a measure of cutaneous barrier function and also reflects skin water content. In this study the transepidermal water loss was measured at four sites pre- and postdialysis in 20 subjects undergoing chronic haemodialysis and in 16 healthy controls. Patients were weighed before and after dialysis and blood was taken for measurement of urea, creatinine, calcium, magnesium, phosphate and haemoglobin. All patients had parathyroid hormone measured within 3 months of the assessment. There was no significant difference in TEWL between patients and controls, with control values in general being between pre- and postdialysis rates of TEWL, and no correlation between TEWL and the presence or absence of pruritus. There was no significant differences between the pruritic and non-pruritic patients for any of the biochemical markers measured. Finally there was no significant correlation between the percentage water loss and TEWL. These findings indicate that pruritus of chronic haemodialysis is not related to abnormalities of cutaneous permeability.