[Changes in body fluid compartments estimated by multifrequency bioelectric impedance analysis in patients treated by hemodialysis]. / Hemodialízist kísérö folyadéktér változások nyomon követése multifrekvenciás bioelektromos impedancia analízissel.

Bioimpedance is a simple non-invasive method of assessing body composition. The aim of this study was to investigate the effect of changes in body fluid related to haemodialysis on measured bioimpedance parameters, to determine correlation between bioimpedance data and the volume of ultrafiltratum, and to collect data on alterations of body fluids resulting from a treatment. Measurements were done on 19 patients (mean age 36.7 years) prior to and after haemodialysis. After dialysis we found significantly higher impedance values on each measured frequency (1, 5, 10, 50, 100 kHz) (p < 0.001). An inverse correlation was found between the changes in body weight (x) and resistance at 50 kHz (y): y = 8.4830-2.1850x (r = 0.7167, p < 0.01). Total body water calculated by bioimpedance analysis (BIA) decreased from 38.47 +/- 8.567 litres (56.07%) to 35.06 +/- 8.045 significantly (p < 0.001), and the reduction of extracellular water proved to be also significant [from 15.76 +/- 2.992 litres (22.97%) to 14.06 +/- 2.736 litres (21.17%), p < 0.001]. The relationship between the change in calculated body water (x) and the volume of ultrafiltratum (y) is: y = -0.5590 + 0.5864x (r = 0.4898 p < 0.05), bioimpedance in our study overestimated the fluid loss by 55%. The intradialytical shifts between extra- and intracellular spaces might be responsible for the difference in the two values.

[Nocturnal enuresis and diurnal changes in extracellular fluid space in childhood]. / Enuresis nocturna és az extracelluláris folyadéktér diurnális változásai gyermekkorban.

Diurnal changes of extracellular body water in enuretic (n = 8) and healthy children (n = 8) and plasma antidiuretic hormone level were examined in enuretic patients, using bioelectrical impedance analysis and radioimmunoassay. In enuretic children day/night values of extracellular space were 25.81% (10.90 l) vs 25.00% (10.52 l), with a night reduction of 3.13% (daytime 100%) (0.38 l). In controls the same parameters were 24.92% (11.88 l) vs 24.82% (11.80 l), the difference is 0.44% (0.08 l). In patients plasma antidiuretic hormone values were 2.96 pM/ml during the day and 2.70 pM/ml in the night. Results show, that in enuretic children there is a nocturnal reduction in extracellular water (p < 0.01), and the physiological nocturnal rise in antidiuretic hormone secretion in absent.