P1080INCREASE OF POST DIALYSIS HEMOGLOBIN CONCENTRATION IS MORE APPROPRIATELY EXPLAINED BY PLASMA VOLUME CHANGE THAN INTRADIALYTIC WEIGH LOST

Background and Aims It is well known that haemoglobin significantly increases after haemodialysis and it is associated with the rate of weight loss during dialysis. However, it has been shown that the increase in haemoglobin is not always proportional to the rate of body weight loss during haemodialysis (ultrafiltration). The purpose of the study was to investigate the correlation between haemoglobin changes, body weight loss and plasma volume changes during haemodialysis Method A prospective study was performed on 92 patients in mid-week treatments. Pre-dialysis and post-dialysis haemoglobin and weight were measured. 27 patients were excluded because clinical instability, no change or a decrease in Hb and low pre-dialysis haemoglobin (< 9 g/dL). The correlation was statistically significant between %ΔPV and ΔHb in both groups (R2=0.59), whereas the correlation between %ΔBW and ΔHb was lower (R2=0.19). So, analysis show that only 19% of the variability in haemoglobin is explained by %ΔBW, and that 59% of the variability in haemoglobin is explained by %ΔPV. Results The mean age was 61.16 ± 13.11 year. The men were 52 (56%). The mean pre-dialysis Hb was 11.31 ± 1.16 g/dL, the mean post-dialysis Hb level was 12.53 ± 1.47 g/dL. The mean absolute change of haemoglobin (ΔHb g/dL) and percent of change of haemoglobin (%ΔHb) were 1.22 ± 0.76 and 9.44 ± 5.31, respectively. Average percent of weight change (%ΔBW) was - 2.44 ± 1.01. Percent of plasma volume change was - 9.22 ± 5.46. The patients were divided in two groups according post-dialysis haemoglobin level: Group A with haemoglobin Hb < 13 g/dL (64 patients) and group B with Hb ≥13 g/dL (28 patients). The mean time average haemoglobin concentration (TAC Hb) in all patients was 11.68 ± 1.11 g/dL.(Predicted Hb TAC was calculated according Krisper′s formula) In both groups there was an increase in %ΔHb, but in the group with post dialysis Hb ≥ 13 g/dL, %ΔHb was greater than in group B with post dialysis Hb < 13 g/dL (13.08 ± 5.11 versus 7.87± 4.61, P = 0.000) despite the relatively small difference of %ΔBW between the two groups (- 2.85 ± 0.95 versus - 2.23 ± 1.02; P = 0.010). However, the difference in %ΔPV between the two groups was significant (- 12.90 ± 5.63 versus - 7.61 ± 4.57; P < 0.000). Conclusion The intradialytic changes in haemoglobin levels are predominantly determined by changes in plasma volume. Changes in body weight are of little predictive value in evaluation of variation of haemoglobin levels. TAC Hb determination should be performed in patients with large variations in plasma volume, because the plasma volume has very little effect on TAC Hb.

Do Male 100-km Ultra-Marathoners Overdrink?

Purpose:Fluid overload is considered a main risk factor for exercise-associated hyponatremia (EAH). The aim of this study was to investigate the incidence of EAH in ultra-runners at the 100 km ultra-run in Biel, Switzerland.Methods:Pre- and postrace, body mass, urinary specific gravity, hemoglobin, hematocrit, plasma [Na+], and plasma volume were determined.Results:Of the 145 finishers, seven runners (4.8%) developed asymptomatic EAH. While running, the athletes consumed a total of (median and interquartile ranges) 6.9 (5.1-8.8) L over the 100 km distance, equal to 0.58 (0.41-0.79) L/h. Fluid intake correlated negatively and significantly with race time (r = -.50, P < .0001). Body mass decreased, plasma [Na+] remained unchanged, hematocrit and hemoglobin decreased, and urinary specific gravity increased. Plasma volume increased by 4.6 (-2.3 to 12.8) %. Change in body mass correlated with both postrace plasma [Na+] and Δ plasma [Na+]. Postrace plasma [Na+] correlated to Δ plasma [Na+]. Fluid intake was associated neither with postrace plasma [Na+] nor with Δ plasma [Na+]. Fluid intake was related to Δ body mass (r = .21, P = .012), but not to postrace body mass. Fluid intake showed no correlation to Δ plasma volume. Change in plasma volume was associated with postrace [Na+].Conclusions:Incidences of EAH in 100 km ultra-marathoners were lower compared with reports on marathoners. Body mass decreased, plasma volume increased, and plasma [Na+] was maintained. Since fluid intake was related neither to Δ plasma volume nor to Δ plasma [Na+], we assume that factors other than fluid intake maintained body fluid homeostasis.