Calf bioimpedance ratio improves dry weight assessment and blood pressure control in hemodialysis patients.

Background: Chronic fluid overload due to overestimation of dry weight (DW) is the major factor in the development of hypertension in hemodialysis (HD) patients. The present study was undertaken to investigate whether bioimpedance ratio in the calf (Calf-BR = impedance at 200 kHz/impedance at 5 kHz) could be a useful hydration marker for estimation of DW and facilitate better control of blood pressure (BP) in HD patients.

Methods: Target range of Calf-BR was derived from 157 healthy Chinese subjects. Post-dialysis Calf-BR was measured in 117 stable, non-edematous HD patients. Those with Calf-BR(s) above target level had their DW(s) gradually reduced under the guidance of Calf-BR.

Results: The Calf-BR was normally distributed and increased with age, but was independent of BMI and gender in both healthy subjects and dialysis patients. HD patients with Calf-BR above age-stratified target range had significantly higher home BP, in spite of more antihypertensive treatments (p = 0.058). The patients who reached the target range of Calf-BR by decreasing DW, had their home BP significantly decreased, along with reduction in antihypertensive medications (p = 0.012).

Conclusion: Recognition and correction of chronic fluid overload based on age-stratified Calf-BR is helpful in hypertension control in Chinese HD patients.