Bioelectrical impedance analysis in the assessment of hydration status in peritoneal dialysis patients.

OBJECTIVE

Assessment of fluid status in chronic peritoneal dialysis (PD) patients is complex. Clinical evaluation based solely on body weight, blood pressure, volume of ultrafiltration (UF) and peripheral edema is insufficient. A non-invasive test, bioelectrical impedance analysis (BIA) might be of potential benefit.

AIM

To test whether BIA correlates with other ancillary markers of extracellular fluid volume, namely B-type natriuretic peptide (BNP), residual renal function (RRF) and UF, and whether BIA provides complementary information in categorizing PD patients vis-à-vis hydration status.

METHODS

A cross-sectional study of 61 out-patients on chronic PD. Single-frequency BIA measurements of resistance/height were divided into tertiles (lowest: <253 Ω/m; middle: >253 Ω/m and <316 Ω/m; highest: >316 Ω/m).

RESULTS

Compared to patients in the highest tertile of BIA (least fluid), patients in the lowest tertile (most fluid) had highest BNP, RRF and UF (93.5 vs. 55.0 pg/ml, p = 0.029; 850 vs. 300 ml/day, p = 0.05; and 1.75 vs. 1.21 l/day, p = 0.023, respectively).

CONCLUSIONS

BIA tertiles categorized PD patients who differed in BNP, RRF and UF in a stepwise pattern, suggesting BIA may better inform hydration status, and serve as an additional clinical tool in management of chronic PD patients.