Quantification of excretory renal function and urinary protein excretion by determination of body cell mass using bioimpedance analysis

Abstract

BackgroundCreatinine clearance (CrCl) based on 24 h urine collection is an established method to determine glomerular filtration rate (GFR). However, its measurement is cumbersome and the results are frequently inaccurate. The aim of this study was to develop an alternative method to predict CrCl and urinary protein excretion based on plasma creatinine and the quantification of muscle mass through bioimpedance analysis (BIA).MethodsIn 91 individuals with normal and impaired renal function CrCl was measured from 24 h urine excretion and plasma creatinine concentration. A model to predict 24 h-creatininuria was developed from various measurements assessing muscle mass such as body cell mass (BCM) and fat free mass (FFM) obtained by BIA, skinfold caliper and other techniques (training group, N = 60). Multivariate regression analysis was performed to predict 24 h-creatininuria and to calculate CrCl. A validation group (N = 31) served to compare predicted and measured CrCl.ResultsOverall (accuracy, bias, precision, correlation) the new BIA based prediction model performed substantially better compared with measured CrCl (P15 = 87 %, bias = 0, IQR of differences = 7.9 mL/min/1.73 m2, R = 0.972) versus established estimation formulas such as the 4vMDRD (P15 = 26 %, bias = -8.3 mL/min/1.73 m2, IQR = 13.7 mL/min/1.73 m2, R = 0.935), CKD-EPI (P15 = 29 %, bias = -7.0 mL/min/1.73 m2, IQR = 12.1 mL/min/1.73 m2, R = 0.932, Cockcroft-Gault equations (P15 = 55 %, bias = -4.4 mL/min/1.73 m2, IQR = 9.0 mL/min/1.73 m2, R = 0.920). The superiority of the new method over established prediction formulas was most obvious in a subgroup of individuals with BMI > 30 kg/m2 and in a subgroup with CrCl > 60 mL/min/1.73 m2. Moreover, 24 h urinary protein excretion could be estimated accurately by normalization with 24 h-creatininuria derived from BIA based BCM.ConclusionPrediction of CrCl based on estimated urinary creatinine excretion determined from measurement of BCM by BIA technique is both accurate and convenient to quantify renal function in normal and diseased states. This new method may become particularly helpful for the evaluation of patients with borderline renal insufficiency and/or with abnormal body composition.

Estimation of Urinary Creatinine Excretion and Prediction of Renal Function in Morbidly Obese Patients: New Tools from Body Composition Analysis

“…Limitations of this study are its monocentric nature and the need for further external validation of the proposed prediction formulas. Recently, other authors confirmed the accuracy of the prediction of UCr and CCr from BCM and suggested that this method may become particularly helpful for the evaluation of patients with abnormal body composition [39]. The results of our study indicate that an accurate prediction of UCr is possible when the measurement of BCM is added in the prediction formula.…”

International Collaboration for the Epidemiology of eGFR in Low and Middle Income Populations - Rationale and core protocol for the Disadvantaged Populations eGFR Epidemiology Study (DEGREE)

“…Adjustment of measures of creatinine based renal clearance for estimates of creatinine production have been shown to provide a more precise estimate of excretory function across a range of physical builds and renal function [21, 22]. Simple bioimpedence devices produce highly reproducible measurements, are now routinely in use by nutritional researchers globally and are available cheaply.…”

Estimating of Residual Kidney Function by Multi-Frequency Bioelectrical Impedance Analysis in Hemodialysis Patients Without Urine Collection

“…On the basis of study by Donadio et al [14], Flury et al [16] elaborated and validated an equation incorporating body cell mass (BCM) obtained by BIA to predict creatinine clearance in CKD patients without timed urine collection. Using predicted muscle mass, achieved by BIA measurements, Macdonald et al [15] improved the prediction of GFR measured by renal inulin clearance in 75 non-diabetic CKD patients.…”

“…Currently, several GFR predicting equations utilizing BIA measurements and anthropometric data are valid for general population [14] and non-dialysis chronic kidney disease (CKD) patients [15-16]. So far there has been no attempt to use BIA measurements to calculate residual GFR in dialysis population.…”