Estimation of extracellular fluid volume in children

Many equations have been developed to estimate various body fluid volumes from height and weight, but few have been developed for children. The aim of this study was to compare four height/weight formulae for estimating extracellular fluid volume (eECV) in children against measured extracellular fluid volume (mECV).

The mECV was obtained from plasma Cr-51-EDTA clearance data used for routine measurement of glomerular filtration rate (GFR) in two groups of children (n=182 and 69, respectively). eECV obtained using the formulae of Abraham et al. (Clin J Am Assoc Nephrol 6:741-747, 2011) and Friis-Hansen (Pediatrics 28:169-181, 1961) were compared with mECV in both patient groups. The formulae of Bird et al. (J Nucl Med 44:1037-1043, 2003) and of Peters (Nucl Med Commun 32:375-380, 2011) were originally based on groups 1 and 2, respectively, so the eECV from them was compared with the mECV in groups 2 and 1, respectively.

The eECV from the Friis-Hansen formula underestimated the mECV in larger children. Biases (mean differences between eECV and mECV) from the Bird (0.146 l) and Peters (0.029 l) formulae were not significantly different from zero, but those from the Abraham formula was higher than zero (0.694 and 0.588 l in groups 1 and 2; p<0.001). Precisions (standard deviations of the biases) of these three formulae were similar, ranging from 0.731 l (Peters) to 0.878 l (Abraham, group 2; p>0.1).

The formulae of Bird, Peters and Abraham have similar precisions. The higher bias of the Abraham formula is probably due to the higher values of mECV on which their formula was based. The Friis-Hansen formula no longer has a place.