THE ADJUSTMENT OF POSTDIALYSIS DRY-WEIGHT BASED ON NONINVASIVE MEASUREMENTS IN CHILDREN

Background. The clinical criteria, to assess hydration status are not always reliable. Hence, the development of techniques to estimate more accurately post-dialysis dry weight (DW) remains a major challenge. T he present study evaluates the value of the inferior vena cava (IVC) d iameter, plasma concentration of atrial natriuretic peptide (ANP), and plasma renin activity (PRA in determining the DW in chronic haemodial ysis children. Methods. Twelve overhydrated haemodialysis patients (4 girls, 8 boys) with a mean age of 12.8 were admitted to the study. Cli nical, electrocardiographic, telecardiographic and echocardiographic f indings, IVC and collapsibility indices and plasma concentrations of A NP and PRA were investigated before and after ultrafiltration (UF) the rapy. Twelve age-matched normal children were studied as controls. Ana lysis of variance and Dunnett's test were applied for comparisons betw een patients and controls. Results. Following UF therapy the patients' mean IVC collapsibility index was increased from 42.3 to 53.6% and IV C index was decreased from 1.08 to 0.81 cm/m(2), both statistically si gnificant, The pre-UF therapy collapsibility and IVC indices of the pa tient group were significantly different from those of the control gro up (56.9% and 0.70 cm/m(2) respectively). The patients' mean plasma co ncentrations of ANP were: 171 +/- 47.4 pg/ml before UF, 129 +/- 51.3 p g/ml after UF and 102 +/- 38.7 pg/ml in the control group. The ANP lev els of the patients showed a significant decrease following the UF the rapy, PRA was measured as 0.82 ng/ml/h before UF and 1.08 ng/ml/h afte r UF, bur the increase was not statistically significant. Conclusions. Our findings revealed increased diameter of the IVC and plasma ANP co ncentrations and decreased collapsibility due to overhydration. Echogr aphy of IVC may be a promising non-invasive tool to estimate the DW in haemodialysis children. Further studies providing normative values fo r the IVC indices in both haemodialysis and normal children are requir ed.