Estimation of Dry Weight in Children with Oedematous Nephropathy

Abstract

Nephrotic syndrome (NS) and acute glomerulonephritis (AGN) are two leading childhood renal disorders in the tropics that present commonly with oedema and therefore increased weight. Knowledge of the dry weight of oedematous patients will provide more objective assessment of the degree of fluid retention and would also guide fluid electrolyte and drug management. All children admitted for NS and AGN to the Paediatric Nephrology Unit of University of Ilorin Teaching Hospital, Ilorin between 2004-2008 were recruited for the study. For each child, the oedematous weight was recorded at admission and the dry weight was determined when the oedema became clinically undetectable. The oedema and dry weight were computed and compared. The weight differential and percentage losses for each patient were also computed. A formula for estimation of dry weight in the oedematous nephropathy was then derived. A total of 37 children were recruited for the study comprising 31 males and 6 females giving a male /female ratio of 5.2:1. Thirty-three children were diagnosed as NS; the other four children had AGN. The weight range among all the NS children was 12.0-68.0 kg while that among the AGN was 12.033.7 kg. Oedematous weight of the children with NS ranged from 12.0-68.0 kg while that of children
with AGN ranged from 12.0-33.7 kg. Dry weight among children with NS was10.0-53.1kg, while that among children with AGN was 11.5-30.0kg. Weight loss among children with NS ranged from 1.2-21.0kg (percentage weight loss 4.8-43.5%) and among children with AGN, weight loss was 0.5-5.2kg (percentage weight loss 4.2-26.4%). Based on the mean weight loss, a formula (n-0.18n or n-0.2n) was proposed for children with NS while the formula (n0.13n or n-0.1n) was proposed for children with AGN. The formula for the estimation of dry weight among children with NS and AGN was (n-0.2n) and (n-0.1n) respectively where n is the oedematous weight. The formula for the estimation of dry weight in all children with oedematous nephropathy was (n-0.176n or n0.2n).