Plasma human, dialysed

In the hemofiltration HF (i.e., ultrafiltration see Section 8.3) of blood, using an appropriate membrane, all of the solutes in plasma below a certain molecular weight will pass into the filtrate at the same rate, irrespective of their molecular sizes, as occurs in the human kidney glomeruli. Since its first proposal in 1967 [14], HF has been studied extensively [15-17]. Although a dialysate solution is not used in HF, the correct amount of substitution fluid must be added to the blood of the patient, either before or after filtration, to replace all the necessary blood constituents that are lost in the filtrate. This substitution fluid must be absolutely sterile, as it is mixed with the patient s blood. For these reasons, HF is more expensive to perform than hemodialysis, and so is not generally used to the same extent. 

Conventional hemodialysis is of little value in the treatment of methylmercury poisoning because methylmercury concentrates in erythrocytes, and little is contained in the plasma. However, it has been shown that L-cysteine can be infused into the arterial blood entering the dialyzer to convert methylmercury into a diffusible form. Both free cysteine and the methylmercury—cysteine complex form in the blood and then diffuse across the membrane into the dialysate. This method has been shown to be effective in humans. Studies in animals indicate that succimer may be more effective than cysteine in this regard. 

Patients suffering from renal failure and receiving dialysis treatment frequently suffer from a normocytic anemia successfully treated with human recombinant erythropoietin, a regulatory protein synthesized by the kidney. However, patients often also exhibit a microcytic, hypochromic anemia that can be separated from the normocytic anemia of renal insufficiency, and that is refractory to erythropoietin (Rosenlof et al. 1990). Al administration to animals produces a similar microcytic anemia (Touam et al. 1983 Fulton and Jeffery 1993). In addition, not only can the anemia be reversed by desferrioxamine treatment (Tielmans et al. 1985), but a prospective clinical study correlated plasma Al levels with severity of the anemia (Short et al. 1980). Patients undergoing hemodialysis with Al-contaminated fluids showed an increased plasma Al and decreased hematocrit both parameters were then reversed when the patients were switched to an Al-free dialysate. 

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