LABORATORY PREDICTORS OF FLUID DEFICIT IN ACUTELY DEHYDRATED CHILDREN

To determine which laboratory studies are most predictive of the fluid deficit in acutely dehydrated children, we studied a convenience samp le of 40 children requiring intravenous fluid resuscitation. Nine labo ratory studies (serum BUN/cr, total serum CO2, serum uric acid, serum anion gap, urine anion gap, venous pH, venous base deficit, urine spec ific gravity, and fractional excretion of sodium) were individually as sessed in simple linear regression models with fluid deficit as the de pendent variable. Only the serum BUN/cr and serum uric acid were signi ficantly associated with increasing fluid deficit (r=0.52, P=0.0005 an d r=0.35, P=0.03, respectively). The sensitivities and specificities o f these two laboratory studies for the detection of >5% fluid deficit were poor. Conventional laboratory studies used to assess dehydration in children are poorly predictive of fluid deficits.