Effect of different modes of dialysis on serum erythropoietin levels in pediatric patients. A report of the Southwest Pediatric Nephrology Study Group

Managing Patients with Failing Kidney Allograft: Many Questions Remain

Patients who receive a kidney transplant commonly experience failure of their allograft. Transplant failure often comes with complex management decisions, such as when and how to wean immunosuppression and start the transition to a second transplant or to dialysis. These decisions are made in the context of important concerns about competing risks, including sensitization and infection. Unfortunately, the management of the failed allograft is, at present, guided by relatively poor-quality data and, as a result, practice patterns are variable and suboptimal given that patients with failed allografts experience excess morbidity and mortality compared with their transplant-naive counterparts. In this review, we summarize the management strategies through the often-precarious transition from transplant to dialysis, highlighting the paucity of data and the critical gaps in our knowledge that are necessary to inform the optimal care of the patient with a failing kidney transplant.

Intraperitoneal Administration of Recombinant Human Erythropoietin

Objective

To determine the efficacy and safety of intraperitoneal administration of recombinant human erythropoietin (rHuEPO) in continuous ambulatory peritoneal dialysis (CAPD) patients compared to subcutaneous rHuEPO.

Design

Prospective analysis of an open, nonrandomized investigation.

Setting

Outpatient CAPD clinics in two university hospitals.

Patients

Nine adult CAPD patients receiving rHuEPO intraperitoneally and 8 patients receiving rHuEPO sub-cutaneously.

Intervention

One hundred units of rHuEPO per kilogram of body weight were administered three times a week for 8 weeks or until the target hematocrit of 35% was reached. Thereafter, dosages of rHuEPO were adjusted for response. Intraperitoneal rHuEPO was administered in 1 L of dialysis solution during the night.

Measurements

Efficacy was assessed by measuring the increase in hemoglobin. Tolerance was assessed by monitoring side effects.

Results

In the first 8 weeks of treatment hemoglobin concentration increased from 64.5±12.9 glL to 98.3±16.1 g/L (p<0.0005) in the intra peritoneally treated group. In the subcutaneously treated group hemoglobin increased significantlyfaster (p<0.05) from 72.5±4.8 g/L to 119.2±11.3 g/L (p<0.0005) in the same period. Antihypertensive medication had to be increased or instituted in most of the patients in both groups. The incidence of peritonitis in the intraperitoneally treated group was not increased when compared to the pretreatment incidence.

Conclusions

Subcutaneously administered rHuEPO is superior to intraperitoneally administered rHuEPO with regard to the required dosages. However, the results of this study show that intraperitoneal administration of rHuEPO might be a convenient and safe alternative when subcutaneous administration is undesirable.

The Effect of Recombinant Erythropoietin on the Early Hematocrit Rise after Capd Initiation

Objective

To determine if the simultaneous initiation of continuous ambulatory peritoneal dialysis (CAPD) and Erythropoietin therapy masks the hematocrit (Hct) rise that frequently follows the initiation of CAPD alone.

Design

Single-center retrospective analysis.

Setting

University multidisciplinary dialysis program.

Patients

All adult CAPD patients with a Hct ≤28% whose nephrologist felt they would benefit from Erythropoietin therapy and who did not have technical reasons for exclusion (N=25).

Interventions

Eight patients began CAPD and Erythropoietin alfa subcutaneously, at a dose of 128:1:9 (X:1:SEM) units/kg/week at the same time. Seventeen patients already on CAPD for 8.7:1:1.5 months received Erythropoietin alfa subcutaneously at a dose of 124:1:7 units/kg/ week. Pre-epoetin Hct's were similar.

Main outcome measures

Hematocrit changes, status of iron stores, incidence of peritonitis, and dosage of Erythropoietin.

Results

In 1 month, the group initiating both therapies simultaneously demonstrated a mean Hct rise of 7.6:1:0.5% while established CAPD patients receiving Erythropoietin increased their Hct by only 4.7:1:1.0% (p<.03). Iron status could not explain this difference. Peritonitis did not appear to dampen the Hct rise following Erythropoietin in either CAPD group. By 2 months after Erythropoietin, the differences were less apparent.

Conclusion

The early rapid increase in Hct is probably the combined effect of CAPD and Erythropoietin and should not be attributed to Erythropoietin alone. When comparing responses to Erythropoietin from patients on different therapies, the timing of dialysis initiation and Erythropoietin initiation must be considered.

Recombinant human erythropoietin therapy in children on dialysis

The addition of recombinant human erythropoietin (rHuEPO) to the therapeutic regimen for children with chronic renal failure (CRF) is one of the most important improvements in care in the last 20 years. Anemia had played an important role in the morbidity of chronic dialysis treatment. Before the availability of rHuEPO, repeated erythrocyte transfusions provided incomplete treatment and had significant long-term sequelae. Recombinant erythropoietin treatment resulted in the amelioration of anemia and marked reduction in transfusions. Additional benefits of the correction of anemia with rHuEPO include improvements in exercise tolerance and regression of ventricular hypertrophy. Many rHuEPO-treated patients have had subjective increases in appetite, but there has been no consistent improvement in dietary intake or anthropometric measures. Correction of anemia with rHuEPO has not been shown to improve the growth of children with CRF receiving dialysis. The most significant adverse effects of rHuEPO are the development of iron deficiency and the exacerbation or development de novo of hypertension. RHuEPO treatment has been shown to treat the anemia of CRF in children safely and effectively. In most cases, putative inhibitors of erythropoiesis and blood loss can be overcome. Many of the symptoms previously ascribed to "uremia" have improved with correction of anemia. The full implications of treatment of anemia with rHuEPO will be clearer when the health outcomes for children who never become severely anemic or require transfusions are more completely studied.

New hormones in the therapeutic arsenal of chronic renal failure. Growth hormone and erythropoietin

Although the benefits of rhGH and r-HuEPO therapy in children with CRF and on dialysis are already significant, further study of these new additions to the therapeutic arsenal remains necessary. Data on the final adult height achieved in patients who receive rhGH are extremely important information that is as yet unavailable. The risks and benefits of raising the target hematocrit to a "normal" value in patients receiving r-HuEPO remains under study. Only when these and other issues are soundly evaluated will the full impact of these medications be understood.

End-stage kidneys are capable of increased erythropoietin production

A relative deficiency of erythropoietin (EPO) is the most important factor responsible for the anaemia of end-stage renal failure. Patients on continuous ambulatory peritoneal dialysis usually maintain a higher haemoglobin concentration than patients on other forms of dialysis. The precise mechanism is uncertain, and there is disagreement over the role of increased EPO production. An 11-year-old boy with end-stage renal failure maintained on overnight cycling peritoneal dialysis developed a reticulocytosis, followed by a marked increase in haemoglobin concentration, shortly after his dialysis schedule was altered to include a full peritoneal cavity during the daytime. This improvement in erythropoiesis was closely associated with an increase in serum EPO concentration. We suggest that the alteration in dialysis may have resulted in enhanced clearance of an inhibitor of EPO production and discuss the possible mechanisms involved.

Trials and tribulations of multicenter studies. Lessons learned from the experiences of the Southwest Pediatric Nephrology Study Group (SPNSG)

Multicenter studies in Pediatric Nephrology have been acknowledged in recent years as an important mechanism for studying renal disease in children. The purpose of this review is to describe some of the experiences of the Southwest Pediatric Nephrology Study Group (SPNSG) in order to assist others in developing their own multicenter studies. The importance of protocol development, including adequate attention to study design, data management, and data analysis, is emphasized. Mechanisms for facilitating the frequency and productivity of study group meetings that are so essential for the success of multicenter studies, are described in some detail. The need and some of the methods for achieving ongoing collaboration within a climate of critical peer review are also discussed. Controversial issues such as authorship and the question of institutional credit for involvement in multicenter studies are discussed in brief. Finally, some of the features of the SPNSG that have permitted us to maintain a relatively high rate of productivity are described. The two most important of these, ongoing commitment to the group and willingness to collaborate across differences of opinion, are stressed throughout the review.

Polyamines in the anemia of end-stage renal disease

The improvement in the anemia in patients with end-stage renal disease (ESRD) on continuous ambulatory peritoneal dialysis (CAPD) suggests that dialyzable substances present in the sera of uremic patients either inhibit erythropoiesis directly or inactivate erythropoietin (EPO). In the present study predialysis sera from patients with ESRD inhibited erythroid colony (CFU-E) (N = 10) formation to a significantly (P less than 0.01) greater degree than granulocyte-macrophage (CFU-GM) (N = 7) colony formation in mouse bone marrow (MBM) cultures. The polyamines spermine (SP) (18 to 560 nm/ml) and spermidine (SD) (4 to 648 nm/ml) exerted a more significant (P less than 0.05) inhibition of CFU-E (N greater than or equal to 5) than that of CFU-GM (N greater than or equal to 5) growth. Concentrations of 0.80, 1.0, and 1.5 nm/ml of putrescine (PU) were 92%, 85%, and 77% of erythroid colony (CFU-E) controls (N = 4) and 104%, 130%, and 127% of CFU-GM controls (N = 4). Putrescine (PU) at 1.5 nm/ml also produced a significant (P less than 0.05) inhibition of CFU-E, whereas CFU-GM were stimulated by PU. These data suggest that predialysis sera from uremic patients, as well as SP, SD, and PU, are selectively more inhibitory to CFU-E than CFU-GM growth. The immunoreactivity of EPO was not significantly changed when it was coincubated with SP, SD and PU and measured by radioimmunoassay. PU was found to inhibit noncompetitively the bioactivity of EPO in a CFU-E assay. These data support the hypothesis that polyamines may be important uremic toxins in the anemia of ESRD.

Measurement of erythropoietin in anephric children. A report of the Southwest Pediatric Nephrology Study Group

Serum erythropoietin (Ep) levels were measured using a highly sensitive radioimmunoassay in 69 children undergoing chronic dialysis; 31 were anephric, whereas 38 were non-nephrectomized (nephric). Twenty-nine normal children were studied as controls. Serum Ep levels in the anephric group were much higher than anticipated (mean 19.7 +/- 1.8 mU/ml), albeit significantly lower than those measured in normal children (mean 26.2 +/- 2.4 mU/ml, P less than 0.05), or in nephric children on dialysis (33.0 +/- 2.9 mU/ml, P less than 0.001). Anephric children on peritoneal dialysis (PD) had significantly (P less than 0.05) higher serum levels of Ep (22.7 +/- 2.4 mU/ml, n = 19) than anephric children on hemodialysis (HD) (15.1 +/- 2.3 mU/ml, n = 12). There was no significant difference between Ep levels in anephric patients dialyzed for less than or equal to 1 year (19.6 +/- 2.0 mU/ml, n = 20) compared with anephric patients dialyzed for more than 1 year (20.0 +/- 3.9 mU/ml, n = 11). Although serum Ep levels showed a tendency to increase with time after nephrectomy, the mean values for less than 3 months (14.7 +/- 1.9), 3 months-12 months (21.0 +/- 2.7), and greater than 12 months (21.6 +/- 6.0) were not significantly different from each other. This demonstration of relatively normal levels of serum Ep in anephric children suggests that extrarenal sites of Ep production are able to exert a significant response to severe anemia in patients who are devoid of renal parenchyma.