Abstract
INTRODUCTION: Maintaining fluid balance is one of the 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. The aim of the study was to compare the conventional methods of monitoring hydration status during hemodialysis with an assessment of skinfold thickness. METHODS: A total of 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. The procedures were repeated at the end of three consecutive hemodialysis sessions. RESULTS: The mean change of skinfold thickness in subscapular area before and after hemodialysis session was -2.2 ± 1.6 mm. A significant correlation was found between the change of extracellular water volume and skinfold thickness before and after hemodialysis (r = 0.33; p = 0.02) and between the change of total water volume and body mass before and after hemodialysis (r = 0.49; p < 0.01). There was also a positive correlation between the change of skinfold thickness and systolic blood pressure before and after a hemodialysis session (R = 0.36; p = 0.01). Dialysis vintage correlated significantly with the changes of plasma nt-proBNP level during hemodialysis (r = 0.40; p = 0.02). Multivariate analysis revealed that baseline body mass, BMI, changes of systolic blood pressure determined the variability of skinfold thickness during hemodialysis. Receiver operating curve analysis revealed that BIA spectrometry was more sensitive and specific than the skinfold thickness assessment for the assessment of hydration condition. CONCLUSION: The simple measurements of skinfold in subscapular area may approximate changes of hydration status but are inferior to BIA spectroscopy. Further research is needed to confirm the utility of this method in monitoring blood pressure control in dialysis patients.