['The pathogenesis of pruritus in renal disease is not yet understood. Evidence suggests that mast cells play a role; for example, the number of dermal mast cells is increased in patients on hemodialysis.', 'To investigate a possible role of mast cell tryptase in pruritus of patients undergoing chronic hemodialysis, serum mast cell tryptase concentrations were measured in blood samples taken from 93 such patients, 53 of whom also recorded the severity of their pruritus on a visual analogue scale.', 'Serum mast cell tryptase levels were above 11.4 microg/l (95th percentile) in 84 of 93 hemodialysis patients (90.3 %). The intensity of pruritus correlated significantly (p = 0.014) with the tryptase levels, an associated not yet shown for other mast cell-related parameters.'] Are baseline serum levels of mast cell tryptase raised in hemodialysis patients and associated with severity of pruritus?