Background Maintaining fluid balance is one of major challenges of the dialysis therapy. It includes, in particular, the management of "dry body mass". We postulated that simple measurement of subscapular skinfold thickness before and after hemodialysis could help monitor hydration status in chronic dialysis patients.

Aim of the study The aim of the study was to compare the conventional methods of monitoring hydration status during hemodialysis with an assessment of skin fold thickness.

Materials and Methods 50 participants (21 F, 29 M; age 60 ±15 years) were enrolled. Directly before the hemodialysis session the following parameters were measured: body composition with bioimpedance spectroscopy, skinfold thickness in subscapular area with standardized caliper and blood tests: blood count, urea, n-terminal pro B-type natriuretic peptide (nt-proBNP) and pro-adrenomedullin (pro-ADM). The procedures were repeated at the end of three consecutive hemodialysis sessions.

Inclusion Criteria:

• chronic hemodialysis for at least 3 months

Exclusion Criteria:

• severe mental disabilities, poor compliance, any acute infection, instability of the cardiovascular hemodynamic condition