Anemia of the regular hemodialysis patient and its treatment

In Vitro and in Vivo Studies of Erythropoiesis during Continuous Ambulatory Peritoneal Dialysis

In order to understand the effect of CAPD on the anemia of chronic renal failure, we studied the behaviour of some hematological parameters and of the colony-formation capacity of bone marrow cells in in vitro cultures in patients undergoing this therapy.

Our studies showed a rise in hematocrit, hemoglobin and reticulocyte values, which showed a significant correlation with a recovery of the erythroid cell proliferative activity. Since serum erythropoietin levels do not change, the improvement of bone-marrow function appears to be due to a better clearance (by CAPD) of substances, which inhibit the response of bone marrow to the erythropoietin.

Adequate hemodialysis improves anemia by enhancing glucose-6-phosphate dehydrogenase activity in patients with end-stage renal disease

Background

We conducted this study to determine the erythrocyte glucose-6-phosphate dehydrogenase (G6PD) activity level in patients with end-stage renal disease (ESRD) on maintenance hemodialysis (HD) and to determine the effect of hemodialysis adequacy on G6PD activity levels and its impact on anemia.

Methods

Eighty-two patients (48 men and 34 women) receiving regular hemodialysis for ESRD through arteriovenous fistulae for at least one year prior to the start of the study were enrolled in this study. G6PD activity levels were measured in all patients and the average Kt/V was used as a parameter of HD adequacy. Patients were divided into two groups according to Kt/V values. Group 1 included 45 patients with Kt/V˃1.2 (adequate HD), and group 2 included 37 patients with Kt/V˃1.2 (inadequate HD). The average hemoglobin level and the weekly dose of an erythropoietin-stimulating agent, epoetin alpha (ESA), for each patient were calculated for one year.

Results

The mean (SD) erythrocyte G6PD activity for all patients on hemodialysis was 7.64 ± 1.85 U/g Hb. Patients who had received adequate hemodialysis had a significantly higher average erythrocyte G6PD (mean (SD) = 9.2 ± 0.7 U/g Hb) compared to patients who had inadequate hemodialysis (mean (SD) = 5.7 ± 0.7U/g Hb) (P-value <0.005). The mean hemoglobin concentration was significantly higher in patients with adequate hemodialysis compared to those with inadequate hemodialysis.

Conclusion

Our study demonstrated the beneficial effect of adequate hemodialysis in correcting anemia by enhancing the erythrocyte G6PD activity in patients.

Optimization of anemia treatment in hemodialysis patients via reinforcement learning

OBJECTIVE

Anemia is a frequent comorbidity in hemodialysis patients that can be successfully treated by administering erythropoiesis-stimulating agents (ESAs). ESAs dosing is currently based on clinical protocols that often do not account for the high inter- and intra-individual variability in the patient's response. As a result, the hemoglobin level of some patients oscillates around the target range, which is associated with multiple risks and side-effects. This work proposes a methodology based on reinforcement learning (RL) to optimize ESA therapy.

METHODS

RL is a data-driven approach for solving sequential decision-making problems that are formulated as Markov decision processes (MDPs). Computing optimal drug administration strategies for chronic diseases is a sequential decision-making problem in which the goal is to find the best sequence of drug doses. MDPs are particularly suitable for modeling these problems due to their ability to capture the uncertainty associated with the outcome of the treatment and the stochastic nature of the underlying process. The RL algorithm employed in the proposed methodology is fitted Q iteration, which stands out for its ability to make an efficient use of data.

RESULTS

The experiments reported here are based on a computational model that describes the effect of ESAs on the hemoglobin level. The performance of the proposed method is evaluated and compared with the well-known Q-learning algorithm and with a standard protocol. Simulation results show that the performance of Q-learning is substantially lower than FQI and the protocol. When comparing FQI and the protocol, FQI achieves an increment of 27.6% in the proportion of patients that are within the targeted range of hemoglobin during the period of treatment. In addition, the quantity of drug needed is reduced by 5.13%, which indicates a more efficient use of ESAs.

CONCLUSION

Although prospective validation is required, promising results demonstrate the potential of RL to become an alternative to current protocols.

Anemia in renal disease: diagnosis and management

Chronic kidney disease (CKD) is a widespread health problem in the world and anemia is a common complication. Anemia conveys significant risk for cardiovascular disease, faster progression of renal failure and decreased quality of life. Patients with CKD can have anemia for many reasons, including but not invariably their renal insufficiency. These patients require a thorough evaluation to identify and correct causes of anemia other than erythropoietin deficiency. The mainstay of treatment of anemia secondary to CKD has become erythropoiesis-stimulating agents (ESAs). The use of ESAs does carry risks and these agents need to be used judiciously. Iron deficiency often co-exists in this population and must be evaluated and treated. Correction of iron deficiency can improve anemia and reduce ESA requirements. Partial, but not complete, correction of anemia is associated with improved outcomes in patients with CKD.

Treatment of refractory anemias with methenolone

A therapeutic trial with methenolone (Primobolan) in 19 consecutive patients with different types of refractory anemia is reported. The remission frequencies were: pancytopenia 3/6, bicytopenia 2/4, refractory anemia with hyperplastic marrow 1/5, myelofibrosis 1/4. There was no obvious prolongation of survival in the patients responding. Side-effects were negligible.

Iron therapy in patients undergoing maintenance hemodialysis

Twelve patients in maintenance hemodialysis, receiving long-term oral iron therapy, have been treated with i.v. iron dextran, in order to evaluate the effect on the Hb level. Both Hb and hematocrit were unchanged before and after the iron dextran infusion (p greater than 0.5, p greater than 0.7, respectively). Oral iron therapy is usually sufficient to maintain an adequate iron balance in dialysed patients and should be preferred to parenteral iron in view of the better utilization and absence of side-effects. The indication for parenteral iron should be limited to patients with impaired gastrointestinal iron absorption.

Would artificial neural networks implemented in clinical wards help nephrologists in predicting epoetin responsiveness?

Background

Due to its strong intra- and inter-individual variability, predicting the ideal erythropoietin dose is a difficult task. The aim of this study was to re-evaluate the impact of the main parameters known to influence the responsiveness to epoetin beta and to test the performance of artificial neural networks (ANNs) in predicting the dose required to reach the haemoglobin target and the monthly dose adjustments.

Methods

We did a secondary analysis of the survey on Anaemia Management in dialysis patients in Switzerland; a prospective, non-randomized observational study, enrolling 340 patients of 26 centres and in order to have additional information about erythropoietin responsiveness, we included a further 92 patients from the Renal Services of the Ente Ospedaliero Cantonale, Bellinzona, Switzerland. The performance of ANNs in predicting the epoetin dose was compared with that of linear regressions and of nephrologists in charge of the patients.

Results

For a specificity of 50%, the sensitivity of ANNs compared with linear regressions in predicting the erythropoietin dose to reach the haemoglobin target was 78 vs. 44% (P < 0.001). The ANN built to predict the monthly adaptations in erythropoietin dose, compared with the nephrologists' opinion, allowed to detect 48 vs. 25% (P < 0.05) of the patients treated with an insufficient dose with a specificity of 92 vs. 83% (P < 0.05).

Conclusion

In predicting the erythropoietin dose required for an individual patient and the monthly dose adjustments ANNs are superior to nephrologists' opinion. Thus, ANN may be a useful and promising tool that could be implemented in clinical wards to help nephrologists in prescribing erythropoietin.

Hemoglobin cycling in hemodialysis patients treated with recombinant human erythropoietin

BACKGROUND

Treatment with recombinant human erythropoietin (rHuEPO) has been a major advance for the management of anemia in patients on hemodialysis. Therapy, however, is often observed to be associated with recurrent cyclic fluctuations in hemoglobin levels. The purpose of this analysis was to describe the phenomenology of hemoglobin cycling during rHuEPO treatment.

METHODS

Data were analyzed for 281 hemodialysis patients treated at Winthrop-University Hospital Dialysis Centers between 1998 and 2003. Eligible patients' first full 1-year period with less than 10 hospital days was studied. Hemoglobin cycling (cycles with amplitude >1.5 g/dL and duration >8 weeks) and excursions (half of one full cycle) were analyzed.

RESULTS

Greater than 90% of patients experienced hemoglobin cycling. The mean number of hemoglobin excursions was 3.1 +/- 1.1 per patient/year. The mean amplitude per hemoglobin excursion was 2.51 +/- 0.89 g/dL. The mean duration of hemoglobin excursions was 10.3 +/- 5.1 weeks. Factors associated with initiation of up excursions included increases in rHuEPO dose (84%), intravenous iron treatment initiation or increase in dose (27%), posthospital discharge (36%), factors associated with down excursions included rHuEPO dose hold (15%) or dose reduction (62%), infection (6%), discontinuation of intravenous iron therapy (5%), and hospitalization (14%). Patients with frequent hemoglobin cycling (>two full cycles per year) were characterized as being more responsive to rHuEPO [index of EPO responsiveness (ERI) 1036 +/- 659 compared to 1992 +/- 701 for other patients] (P = 0.02).

CONCLUSION

Hemoglobin cycling is a common occurrence in rHuEPO-treated hemodialysis patients. It is most closely associated with frequent rHuEPO dose changes, hospitalization, and iron treatment practices.

Reduced requirement for erythropoietin with quotidian hemodialysis therapy

Quotidian (daily) hemodialysis has many potential advantages over conventional three times weekly hemodialysis, including improved control of anemia. However, previous reports do not consistently describe beneficial effects regarding anemia and erythropoietin requirements. We sought to determine whether erythropoietin dose is altered in this form of therapy, and elucidate the potential contributing factors. An analysis of an ongoing, nonrandomized, prospective trial of daily nocturnal, daily short, and their cohort of conventional hemodialysis controls was performed. Those patients who had completed 15 months of the trial were analyzed, which include nine patients in the quotidian dialysis group and nine cohort controls receiving conventional three times weekly dialysis. At 15 months, the weekly Kt/V in the quotidian group was 6.8 (+/-0.6) and 4.5 (+/-0.4) in the conventional group (p = 0.001). Mean erythropoietin dose fell in the quotidian group from 87 (+/-66) to 53 (+/-50) U/week per kg (p = 0.020). The mean hemoglobin rose from 115 (+/- 18) to 129 (+/- 14) g/L (p = 0.008). There was no significant change in erythropoietin dose or hemoglobin in the conventional hemodialysis group. Serum ferritin and the transferrin-saturation did not change significantly and remained above 100 microg/L and 20%, respectively, throughout. Serum albumin and C-reactive protein were similar between the quotidian and conventional dialysis groups and did not change over time. In patients who were receiving conventional thrice weekly hemodialysis, initiation of quotidian hemodialysis led to a 39% reduction in erythropoietin dose at 15 months, most likely due to the increased dose of delivered dialysis.

Hemeral (daily) hemodialysis

Hemodialysis is generally performed 3 times per week, a treatment prescription not based on optimizing the physiology of the normal kidney that maintains body homeostasis by removing water and waste products continuously and efficiently. Peritoneal dialysis might be continuous but it is not efficient. Daily hemodialysis is both frequent and efficient and theoretically should be superior to other forms of dialysis for renal replacement therapy. There is again a growing interest in daily hemodialysis (it was originally described in 1969), and a number of investigators in North America and Europe are using it. As yet, there have been no randomized prospective studies comparing hard outcomes in patients dialyzed by conventional 3-times-per-week hemodialysis with those treated with daily hemodialysis (either short high-efficiency or long, slow nocturnal). The London, Ontario, study is the first attempt to obtain comparative data. It is a 3-year study to compare daily dialysis patients with cohort controls. To date, the study shows that short daily dialysis does provide more dialysis based on Kt/V than standard therapy. However, predialysis blood urea values are not different because of improved nutrition (increased normalized protein from nitrogen appearance (nPNA) and serum albumin levels). Anemia is improved with less erythropoeitin usage in the study group. Phosphate control is good, but no better than by conventional dialysis and phosphate binders are still required unlike patients receiving nocturnal dialysis. Blood pressure and volume management is better with daily dialysis. So far, the study patients show a trend to less morbidity than their controls, but differences are not (as yet) statistically different. Blood access in daily dialysis dose not cause problems. Quality of life is significantly increased in a number of areas with daily dialysis. The economic impact of daily dialysis is not yet known; the general premise is that the higher dialysis costs attributable to an increment in treatments will be offset by increased wellness and less morbidity with the subsequent beneficial impact on drugs, hospitalizations, and so on. The provision of daily dialysis in the home has attractive economic implications. A considerable growth for this superior form of therapy is expected.

Increased susceptibility to erythrocyte C5b-9 deposition and complement-mediated lysis in chronic renal failure

BACKGROUND

Decreased red blood cell survival contributes to the anemia of chronic renal failure patients. Because patients on chronic dialysis therapy are frequently exposed to excessive complement activation, we investigated the susceptibility of this patient population to erythrocyte C5b-9 deposition, complement-mediated lysis, and ghost formation.

METHODS

We developed a flow cytometric assay using antibodies to both glycophorin and the C5b-9 complex to detect C5b-9 deposition on intact erythrocytes and erythrocyte ghosts. Serum C5b-9 levels and C5b-9 deposition on erythrocyte ghosts were measured by enzyme-linked immunosorbent assay.

RESULTS

A significant increase in C5b-9 deposition on intact erythrocytes was demonstrated in patients with advanced chronic renal failure (2.2 +/- 0.5%) and in patients on chronic maintenance hemodialysis (2.3 +/- 0.4%) compared with normal volunteers (0.9 +/- 0.1%, P = 0.005 vs. chronic renal failure, P < 0.001 vs. chronic hemodialysis patients). There was also a significantly higher percentage of C5b-9-positive erythrocyte ghosts in patients with advanced chronic renal failure (20.6 +/- 5%) and in chronic hemodialysis patients (15.5 +/- 3.1%) compared with normal controls (2.6 +/- 0.9%, P < or = 0.001 vs. advanced chronic renal failure and chronic hemodialysis patients). Treatment of erythrocyte preparations with cobra venom factor, which activates the complement cascade, resulted in dramatic increases in the percentages of C5b-9-positive erythrocyte ghosts in patients with chronic renal failure (49.9 +/- 6.9%) and in chronic hemodialysis patients (45.0 +/- 4.2%) compared with normal volunteers (22.3 +/- 2.7%, P < 0.001 vs. chronic renal failure and chronic hemodialysis patients). Erythrocyte membrane expression of the complement regulatory proteins CD59 and CD55 did not significantly differ between normal controls and hemodialysis patients. Plasma C5b-9 levels after cobra venom factor stimulation were higher in chronic renal failure patients (538 micrograms/ml) compared with normal controls (345 micrograms/ml, P < 0.001).

CONCLUSIONS

Patients with chronic renal failure and on hemodialysis therapy are susceptible to erythrocyte C5b-9 deposition with subsequent lysis and ghost formation. Susceptibility to complement-mediated erythrocyte injury may contribute to the anemia of chronic renal disease.

Recombinant human erythropoietin enhances superoxide production by FMLP-stimulated polymorphonuclear leukocytes in hemodialysis patients

Recombinant human erythropoietin (rHuEPO) is a hematopoietic growth factor that has a broad spectrum of action. We have observed the in vivo and in vitro effects of rHuEPO on the superoxide production of circulating polymorphonuclear leukocytes (PMNs) in hemodialysis patients. The PMNs were separated from heparinized blood after dextran sedimentation and Ficoll-Conray centrifugation and stimulated with formyl-methionyl-leucyl-phenylalanine (FMLP), serum-treated zymosan (STZ), or phorbol myristate acetate (PMA). The in vivo study showed that rHuEPO therapy for 12 weeks enhanced the superoxide production by FMLP-stimulated PMNs (P < 0.01). However, no significant changes on superoxide production was found in either STZ- or PMA-stimulated PMNs. Simultaneous measurement of PGE2 production by PMNs in response to all three stimulants did not show any significant changes after rHuEPO therapy. The direct in vitro effect of rHuEPO on PMNs showed that rHuEPO does not enhance the superoxide production by non-stimulated PMNs. However, preincubation of rHuEPO enhanced superoxide production from FMLP- and STZ-stimulated PMNs. Our results indicate that rHuEPO enhanced FMLP-stimulated superoxide production of PMNs both in vivo and in vitro in hemodialysis patients, which may be responsible for the increased oxidant stress in hemodialysis patients after rHuEPO therapy.

Severity of AIDS and the response to EPO in uremia

To determine the factors that govern their response to erythropoietin (EPO), we conducted a cross-sectional study of all patients in four outpatient hemodialysis facilities in Brooklyn, NY, who had end-stage renal disease (ESRD) and human immunodeficiency virus (HIV) infection and were receiving recombinant EPO. We also compared the hematocrit and EPO requirements of these patients to those of a control group of hemodialysis patients without HIV infection. We documented known duration of HIV infection, and total CD4 count was measured once. In both groups, hematocrit was measured weekly for 5 weeks and a mean value calculated for each subject. Transferrin saturation was measured twice and a mean value calculated for each subject. Intensity of hemodialysis was assessed by measuring both percent reduction of urea and serum albumin concentration twice; mean values were calculated for each subject. Twenty-nine (88%) of 33 study subjects had acquired immunodeficiency syndrome. Mean known duration of HIV infection was 49 +/- 32.5 months (median, 48 months), and mean total CD4 count was 143 +/- 152.4 cells/mm3 (median, 72 cells/mm3). Mean hematocrit in the study subjects was 27.4% +/- 4.7% compared with 27.6% +/- 3.7% in the controls (P = 0.69). Mean thrice-weekly EPO dose was higher in the study subjects (90 +/- 52 U/kg body weight) than in the controls (62 +/- 36 U/Kg body weight) (P = 0.001). Among the study subjects, hematocrit had direct univariate correlations with serum albumin concentration (r = 0.43; P = 0.02), transferrin saturation (r = 0.4; P = 0.03), and percent reduction of urea (r = 0.4; P = 0.02), but not with total CD4 count (r = -0.05; P = 0.8) or known duration of HIV infection (r = -0.11; P = 0.55). There was an inverse correlation between hematocrit and dose of EPO (r = -0.5; P = 0.003). Multiple regression analysis showed that transferrin saturation (P = 0.01) and percent reduction of urea (P = 0.003) had direct correlations with hematocrit after adjustment for other factors. There was an inverse relationship between hematocrit and dose of EPO (P = 0.0006). We conclude that in patients with ESRD and HIV infection receiving hemodialysis, the response to EPO (hematocrit) is modulated by the dose of EPO, quantity of hemodialysis, and transferrin saturation, but not by the severity of HIV disease. Hemodialysis patients infected with HIV receive a higher dose of EPO than those without HIV infection.

The intensity of hemodialysis and the response to erythropoietin in patients with end-stage renal disease

BACKGROUND

Anemia (characterized by a hematocrit of 30 percent or lower) persists in 40 to 60 percent of patients treated for end-stage renal disease with maintenance hemodialysis, despite concomitant erythropoietin (epoetin) therapy. We tested the hypothesis that inadequate dialysis is a key reason for the insufficient response to erythropoietin in patients with end-stage renal disease who are receiving hemodialysis.

METHODS

We prospectively studied 135 randomly selected patients undergoing hemodialysis who had been receiving intravenous erythropoietin for at least four months. The adequacy of dialysis was assessed by measuring the percent reduction in the blood urea nitrogen concentration and the serum albumin concentration. The hematocrit was measured weekly for four weeks, transferrin saturation was measured, and coexisting illnesses were documented. To determine the effect of an increased level of dialysis on the hematocrit, the thrice-weekly schedule of dialysis was increased to raise the mean urea-reduction value from 60.7 to 72 percent for six weeks in 20 consecutive patients whose base-line urea-reduction value was less than 65 percent. The change in the hematocrit in these patients was compared with that observed in the next 20 patients who had an equivalent base-line urea-reduction value but whose level of dialysis was not altered.

RESULTS

The mean hematocrit of the entire group was 29.2 +/- 4 percent, and the mean thrice-weekly dose of erythropoietin was 59 +/- 29 U per kilogram of body weight. The mean serum albumin concentration was 3.8 +/- 0.4 g per deciliter, the mean urea-reduction value was 62 +/- 4.8 percent, and the mean transferrin saturation was 20 +/- 9 percent. Multiple regression analysis revealed direct correlations between the hematocrit and the serum albumin concentration (P = 0.009) and between the hematocrit and the urea-reduction value (P = 0.012) after adjustment for other factors. A logistic-regression analysis indicated that an 11 percent increase in the urea-reduction value doubled the odds that a patient would have a hematocrit above 30 percent. After six weeks of increased intensity of dialysis in 20 patients with base-line urea-reduction values of less than 65 percent, the mean (+/- SE) hematocrit rose from 28.4 +/- 0.78 percent to 32.3 +/- 0.71 percent (P = 0.002); there was no significant change in a control group of 20 patients with equivalent base-line urea-reduction values in whom the dialysis level was not altered (28.2 +/- 0.84 percent to 26.3 +/- 0.85 percent; P = 0.175).

CONCLUSIONS

In patients with end-stage renal disease, inadequate hemodialysis is associated with a suboptimal response to erythropoietin therapy. Increasing the intensity of dialysis in patients with anemia who are receiving inadequate dialysis results in a significant increase in the hematocrit.

Androgens potentiate the effects of erythropoietin in the treatment of anemia of end-stage renal disease

Since androgens may increase the sensitivity of the erythroid progenitors to erythropoietin, the present studies were designed to investigate the effect of administration of androgens on the actions of exogenous erythropoietin (EPO) in hemodialysis patients. Studies were performed in a group of 15 adult male hemodialysis patients. Seven patients were treated with EPO alone at a dose of 2,000 U intravenously (IV) three times a week. An additional group of eight patients was treated with 2,000 U of EPO three times a week and also received 100 mg of nandrolone decanoate intramuscularly (IM) each week. After 12 weeks of therapy, hematocrit values increased slightly in the group receiving EPO alone, from 25.3 +/- 0.8 to 27.4 +/- 1.5. In contrast, EPO in combination with nandrolone decanoate resulted in a greater increase in hematocrit values, from 24.4 +/- 1.4 to 32.9 +/- 1.8 (P less than 0.001). The results show that the groups receiving low-dose EPO alone had a poor erythropoietic response. In contrast, patients receiving androgen in addition to EPO had a significantly greater increase in hematocrit values with treatment. Transfusions were eliminated in both groups of patients. These data show that androgen therapy significantly augments the action of exogenous EPO such that lower doses of EPO are sufficient for an adequate hematopoietic response.

Glutathione peroxidase activity and reduced glutathione content in erythrocytes of patients with chronic renal failure

Erythrocytes from 18 patients with chronic renal failure (CRF) and 10 healthy subjects were examined with respect to glutathione peroxidase (GSH-Px) activity and reduced glutathione (GSH) contents. The activity of GSH-Px and GSH content were found to be lower in RBC from CRF patients as compared with normal RBC. These reduced levels of GSH and GSH-Px in the red cells of uraemic patients may predispose the cells to oxidative damage.

Correlation of clinical and in vitro erythropoietic responses to androgens in renal failure

To assess in vitro erythropoietic cultures as a tool to discriminate between patients whose anemia improves with and those whose anemia fails to improve with androgens, bone marrows of 24 anemic patients receiving maintenance hemodialysis in hormone-depleted plasma clots were cultured. While erythroid colony proliferation in the presence and absence of androgens by cells of seven patients with good clinical outcomes who were initially studied was similar to that of normal donors, it was reduced (P less than 0.001) in cultures of cells from seven patients whose clinical responses were ultimately poor. Fewer than 25 colonies/6 X 10(4) cells at optimal erythropoietin concentrations, and less than a 25% enhancement in colony growth by androgens were observed in only those cultures derived from clinical nonresponder marrows. Using these criteria, nine of ten prospectively classified patients (five clinical responders and four nonresponders) were identified correctly.

The use and misuse of androgens

Because testosterone is rapidly metabolized by the liver, it is necessary either to administer androgens by injection in the form of testosterone esters that are absorbed slowly into the circulation or to administer by mouth derivatives that are slowly metabolized by the liver. The later derivatives, however, have deleterious side effects that limit their usefulness. Long-acting parenteral androgen esters are the treatment of choice in the replacement therapy of male hypogonadism. Because these esters must be hydrolyzed to the free hormone prior to exerting their cellular actions the effectiveness of therapy can be monitored by following plasma testosterone levels. All known effects of the endogenous hormone can be duplicated except for the induction and maintenance of normal spermatogenesis. Androgens have been tried in a variety of clinical situations other than male hypogonadism in the hopes that the nonvirilizing actions would outweigh any detectable side effects. The only disorders in which a salutary effect has been documented are hereditary angioneurotic edema and some patients with anemia due to failure off the bone marrow.

Improving anemia by hemodialysis: effect of serum erythropoietin

Serum erythropoietin (SEP) concentration was measured on two occasions in 42 patients with terminal renal failure (1) immediately before the first hemodialysis, and (2) 3 to 27 months following the onset of regular hemodialysis treatment. Although the hematocrit (Hct) showed an increase in every patient, the SEP concentration decreased in every patient. The mean Hct rose frm 21.7 to 28.6% (volume per volume) P < 0.001), and the SEP dropped from 509 to 182 mU/ml (P < 0.001). This shows that anemia improvement is not a consequence of increased erythropoietin production but that it is most likely due to elimination of an inhibitor of the bone marrow by hemodialysis treatment. The decrease of SEP concentration has to be interpreted as a response to the improved tissue oxygenation that correlates with the hjigher hematocrit or as a consequence of further reduction of renal mass with progress of the renal disease.

Serum ferritin assay and bone-marrow iron stores in patients on maintenance hemodialysis

Fifty-five patients on maintenance hemodialysis underwent bone-marrow aspirations for evaluation of iron stores that were to be compared to concomitant measurements of hematocrit, red blood cell volume, serum iron concentration, total iron binding capacity, transferrin saturation, and serum ferritin concentration. In 42 patients (76.4%), the bone marrow iron stores were found to be absent or deficient. Mean hematocrit for the total group was 26.4%, and red blood cell volume measurement showed a mean value of 41.1% of predicted normal. Results also indicated that serum ferritin was the best predictor of iron storage levels, with diagnostic thresholds of 80 to 350 ng/ml derived from statistical analysis of the data. Other hematologic parameters studied had significantly less correlation with bone-marrow iron stores.

[Plasma erythropoietin and hematocrit under the influence of chronic hemodialysis treatment (author's transl)]

Hematocrit and plasma ESF titers were determined at 2 to 3 weeks intervals in 21 patients with chronic renal failure prior to and during a 15-weeks' period following initiation of chronic intermittent hemodialysis. While hematocrits increased from 22 to 27%, plasma ESF titers were found unchanged between 31 and 35 mU/ml. It can be excluded therefore that the improvement of erythropoiesis following initiation of dialysis was in part due to an increase in plasma ESF titers. The increased erythropoiesis observed is probably not dependent on increased ESF production. A 30-fold ESF deficit existed in patients with renal failure prior to the initiation of hemodialysis when compared with 5 patients with aplastic anemia (hematocrit 23%, plasma ESF titer 1115 mU/ml). At one exception ESF titers up to 500 mU/ml were found in dialysed patients only in combination with anemia due to acute bleeding or iron deficiency. ESF production is appropiate to the degree of anemia in patients with proper renal function after kidney transplantation.

Effect of splenectomy on anemia in patients on regular dialysis treatment

Splenectomy was performed in 7 patients on regular hemodialysis treatment who had disabling anemia. All patients had a short 51Cr red cell survival time and an increased splenic uptake of red cells verified by external counting and computer-aided scintigraphy. The need for blood-transfusions was eliminated in all except one. In all patients the hemoglobin concentration rose after splenectomy. This was probably an effect of a reduced plasma volume and the removal of a large pool of non-circulating red cells. No consistent changes in the red blood cell survival time or the red cell volume were observed. The white cell and the platelet counts in the blood rose to twice the preoperative value. No adverse effect of the splenectomy was observed.