Relationship between values of bioelectrical impedance and creatinine clearance.

This investigation was conducted to determine if measurements of bioelectrical impedance in conjunction with serum creatinine concentrations are useful in predicting creatinine clearance. Twenty-eight healthy volunteers between 23 and 50 years of age followed an individualized protein diet to provide 1.2 g protein/kg/day for 3 consecutive days. At the beginning of day 3, a 24-hour urine collection was initiated. At the midpoint of urine collection, bioelectrical impedance measurements of resistance and reactance were taken, together with a single blood sample for assessment of serum creatinine concentration. Multiple linear regression techniques were used to identify significant values for predicting creatinine clearance. Resistance and serum creatinine concentration were identified as significant predictors. The measured creatinine clearance was compared to that predicted by the impedance-derived model that we developed, as well as other established estimation methods. Mean absolute prediction errors in creatinine clearance using this model were significantly lower than those obtained using four empiric methods. Bioelectrical impedance may provide a noninvasive, quick, and accurate method for predicting creatinine clearance from serum creatinine concentration values.