Chronic renal failure induces anemia and a short erythrocyte life span. Red blood cell (RBC) osmotic fragility is the resistance of RBC hemolysis to osmotic changes that is used to evaluate RBC friability. To find the cause of shortened red cell survival in uremic patients, we evaluated the RBC osmotic fragility in 57 chronic hemodialyzed patients. Each patient had received 12 h of dialysis per week continuously prior to being enrolled in the study. Nineteen healthy volunteers served as a control group. Biochemistry, hemoglobin, electrolyte, osmolarity, β₂-microglobulin, and intact parathyroid hormone were examined before and after the dialysis session. To evaluate the osmotic fragility of RBC, blood samples were collected in heparinized test tubes. Fifty microliters of the RBC of each individual was then incubated in solutions containing a series of various concentrations of NaCl ranging from 0 to 0.6%. The concentration of NaCl at which 50% of RBCs were lysed was considered the median osmotic fragility (MOF). The results showed that the MOF was significantly greater in hemodialyzed patients before dialysis than in the control group (0.41 ± 0.03 vs. 0.39 ± 0.02%). The osmotic resistance to hemolysis was also recorded after dialysis (MOF 0.38 ± 0.03%). Correlation analysis showed that the MOF was significantly correlated with urea nitrogen, serum osmolarity, and intact parathyroid hormone level. In addition, the osmotic fragility was higher in patients who had a predialysis intact parathyroid hormone level >100 pg/dl. In conclusion, hemodialysis can improve the osmotic fragility. The mechanism underlying this improvement may be the removal of low molecular weight uremic toxins, resulting in normalization of serum osmolarity. Our results indicate that parathyroid hormone is probably a major factor influencing RBC osmotic fragility in chronic renal failure.

SUMMARY: Interdialytic weight gain (IDWG) has been reported to contribute to cardiovascular mortality in haemodialysis patients. In order to determine the relationship of IDWG to the pre‐dialysis blood pressure and left ventricular hypertrophy, 168 patients on maintenance haemodialysis were initially evaluated. The IDWG was estimated as the current pre‐dialysis weight minus the preceding post‐dialytic weight and expressed as a proportion (%) of the current dry weight. Patients were divided into two groups: group I consisted of patients with a mean IDWG > 5% each month for 6 months and group II consisted of patients with a mean IDWG < 5% each month for 6 months. As 51 patients had increased IDWG > 5% on more than one occasion, but fewer than six times, they were not included in the above two groups. Thus, 117 patients (33 men, 84 women) were enrolled in this study. All patients received haemodialysis three times a week, with a duration of 4.6 ± 0.5 h per dialysis session. Pre‐dialysis systolic and diastolic blood pressure (SBP, DBP) and left ventricular mass index (LVMI), as determined by echocardiography, were studied regularly. The results demonstrated that the IDWG correlated significantly with age (r = −0.209, P = 0.024) and solute removal index (Kt/V) (r = 0.254, P = 0.006), but did not correlate with pre‐dialysis systolic or diastolic blood pressure. In contrast, LVMI correlated with SBP (r = 0.816, P < 0.001), DBP (r = 0.377, P < 0.001) and age (r = 0.458, P < 0.001). Left ventricular hypertrophy presented in 18 group I subjects (81%) and 68 group II subjects (72%) respectively (P < 0.001). In conclusion, this study shows that excessive IDWG in patients maintained on haemodialysis does not correlate with pre‐dialysis blood pressure, emphasizing that additional factors other than fluid volume may play a role in the control of blood pressure in uraemic patients.

In patients with advanced uremia, rhuEPO therapy may result in improved gonadotropic hormone levels and sexual function. Good dialysis quality may contribute to the increase in the incidence of patients with better sexual function.