The effects of recombinant human erythropoietin on growth and nutritional status

Use of erythropoiesis-stimulating agents in children with chronic kidney disease: a systematic review

Background

Erythropoiesis-stimulating agents (ESAs) revolutionized the management of anaemia in chronic kidney disease (CKD) when introduced in the late 1980s. A range of ESA types, preparations and administration modalities now exist, with newer agents requiring less frequent administration. Although systematic reviews and meta-analyses have been published in adults, no systematic review has been conducted investigating ESAs in children.

Methods

The Preferred Reporting Items for Systematic Reviews and Meta-analyses statement for the conduct of systematic reviews was used. All available literature on outcomes relating to ESAs in children with CKD was sought. A search of the MEDLINE, CINAHL and Embase databases was conducted by two independent reviewers. Inclusion criteria were published trials in English, children with chronic and end-stage kidney disease and use of any ESA studied against any outcome measure. An assessment of risk of bias was carried out in all included randomized trials using the criteria from the Cochrane Handbook for Systematic Reviews of Interventions. Two tables were used for data extraction for randomized and observational studies. Study type, participants, inclusion criteria, case characteristics, follow-up duration, ESA type and dosage, interventions and outcomes were extracted by one author.

Results

Of 965 identified articles, 58 were included covering 54 cohorts. Six were randomized trials and 48 were observational studies. A total of 38 studies assessed the efficacy of recombinant human erythropoietin (rHuEPO), 11 of darbepoetin alpha (DA) and 3 of continuous erythropoietin receptor activator (CERA), with 6 studies appraising secondary outcome measures exclusively. Recruitment to studies was a consistent challenge. The most common adverse effect was hypertension, although confounding effects often limited direct correlation. Two large cohort studies demonstrated a greater hazard of death independently associated with high ESA dose. Secondary outcome measures included quality of life measures, growth and nutrition, exercise capacity, injection site pain, cardiovascular function, intelligent quotient, evoked potentials and platelet function.

Conclusions

All ESA preparations and modes of administration were efficacious, with evidence of harm at higher doses. Evidence supports individualizing treatments, with strong consideration given to alternate treatments in patients who appear resistant to ESA therapy. Further research should focus on randomized trials comparing the efficacy of different preparations, treatment options in apparently ESA-resistant cohorts and clarification of meaningful secondary outcomes to consolidate patient-relevant indices.

Chronic Kidney Disease and Dietary Measures to Improve Outcomes

Chronic kidney disease is an ongoing deterioration of renal function that often progresses to end-stage renal disease. Management goals in children include slowing disease progression, prevention and treatment of complications, and optimizing growth, development, and quality of life. Nutritional management is critically important to achieve these goals. Control of blood pressure, proteinuria, and metabolic acidosis with dietary and pharmacologic measures may slow progression of chronic kidney disease. Although significant progress in management has been made, further research is required to resolve many outstanding controversies. We review recent developments in pediatric chronic kidney disease, focusing on dietary measures to improve outcomes.

Pubertal development in children with chronic kidney disease

Impairment of pubertal growth and sexual maturation resulting in reduced adult height is an significant complication in children suffering from chronic kidney disease (CKD). Delayed puberty and reduced pubertal growth are most pronounced in children with pre-existing severe stunting before puberty, requiring long-term dialysis treatment, and in transplanted children with poor graft function and high glucocorticoid exposure. In pre-dialysis patients, therapeutic measures to improve pubertal growth are limited and mainly based on the preservation of renal function and the use of growth hormone treatment. In patients with end-stage CKD, early kidney transplantation with steroid withdrawal within 6 months of renal transplantation allows for normal pubertal development in the majority of patients. This review focuses on the underlying pathophysiology and strategies for improving height and development in these patients.

Management of anemia with erythropoietic-stimulating agents in children with chronic kidney disease

Anemia management is an important component of the care provided to children with chronic kidney disease (CKD) and influences both morbidity and mortality risk. The introduction of recombinant human erythropoietin to the treatment regimen three decades ago revolutionized the therapy and significantly decreased the need for repeated blood transfusions and exposure to associated risks. Recent data on the efficacy and complications associated with erythropoietic-stimulating agent (ESA) usage has, however, prompted a reassessment of treatment-related recommendations. This review will address these recommendations, in addition to describing pediatric outcomes associated with current ESAs and presenting information on alternative ESAs, many of which will likely soon be incorporated into clinical practice.

Comparison of recombinant human erythropoietin and darbepoetin alpha in children

BACKGROUND

The aim was to compare the clinical efficacy of recombinant human erythropoietin (rHuEPO) and darbepoetin alpha (DA) in the treatment of anemia in children with chronic kidney disease (CKD).

METHOD

Thirty-four (13 female, 21 male) CKD patients were enrolled in the study. Mean age was 11.42 ± 4.05 years. Nine patients were on hemodialysis, 18 were on peritoneal dialysis and seven patients were in CKD stage 4.

RESULTS

Seventeen patients received rHuEPO and the remaining 17 patients received DA. Hemoglobin (Hb) was not significantly different between the two groups during monthly follow up and at the end of 6 months (P > 0.05), but there was a significant increase within each group at the end of 6 months (P = 0.01 for rHuEPO; P = 0.02 for DA). Hb was not different between the patients on and not on dialysis in both groups at the end of the study (P > 0.05). The efficacy of the s.c. and i.v. routes was similar within each group (P > 0.05). Systolic hypertension was observed in only one patient in the DA group, no other adverse effect was observed in either groups.

CONCLUSION

DA is a reasonable alternative to rHuEPO in the treatment of anemia in pediatric CKD patients, due to its clinical efficacy, convenience of use, patient compliance and tolerability.

Hemoglobin target in chronic kidney disease: a pediatric perspective

Erythropoietin has transformed the treatment of the anemia of chronic kidney disease (CKD) by preventing the need for blood transfusions and improving the quality of life in all patients, including children. Anemia in children, in the age group 1-19 years, may be defined as hemoglobin (Hgb) levels < 12.1-13.5 g/dl for boys and < 11.4-11.5 g/dl for girls, based on the National Health and Nutrition Examination Survey (NHANES) norms. The prevalence of anemia in children ranges from 31.2% in stage 1 CKD to 93.3% in stages 4 and 5 CKD. The recent publication of trials evaluating the optimal hemoglobin level in adult CKD patients has generated considerable uncertainty about the target Hgb level in children with CKD. It is unclear whether generalizing of results from these trials in adults to children is appropriate. Adequately powered, randomized, controlled studies have not been conducted on children, and none to our knowledge are currently planned. The Food and Drug Administration (FDA) offers scant guidance on the Hgb target level for children, other than implying that it should be no different from that for adults. The purpose of this editorial is to critically scrutinize whether there is a benefit to the normalization of anemia in children with CKD and whether adoption of the results from adult studies is appropriate.

Anemia in children with chronic kidney disease

Anemia is a common feature of chronic kidney disease, but the management of anemia in children is complex. Erythropoietin and supplemental iron are used to maintain hemoglobin levels. The National Kidney Foundation-Kidney Disease Outcomes Quality Initiative (NKF-KDOQI) clinical practice guidelines for the management of anemia specifically in children were recently published. Pediatric nephrologists are encouraged to use current clinical practice guidelines and best evidence in conjunction with their clinical experience to optimally manage patients with anemia.

Nutrition in children with CRF and on dialysis

The objectives of this study are: (1) to understand the importance of nutrition in normal growth; (2) to review the methods of assessing nutritional status; (3) to review the dietary requirements of normal children throughout childhood, including protein, energy, vitamins and minerals; (4) to review recommendations for the nutritional requirements of children with chronic renal failure (CRF) and on dialysis; (5) to review reports of spontaneous nutritional intake in children with CRF and on dialysis; (6) to review the epidemiology of nutritional disturbances in renal disease, including height, weight and body composition; (7) to review the pathological mechanisms underlying poor appetite, abnormal metabolic rate and endocrine disturbances in renal disease; (8) to review the evidence for the benefit of dietetic input, dietary supplementation, nasogastric and gastrostomy feeds and intradialytic nutrition; (9) to review the effect of dialysis adequacy on nutrition; (10) to review the effect of nutrition on outcome.

Anemia in children with chronic kidney disease

Anemia in children with chronic kidney disease (CKD) is common secondary to inadequate erythropoietin production, iron deficiency, blood loss, inflammation, secondary hyperparathyroidism, uremic toxins, and nutritional deficiencies. Anemia has a variety of deleterious consequences, including associations with increased mortality and left ventricular hypertrophy. Recombinant human erythropoietin is effective in treating anemia in children with CKD, and recent studies show that darbepoetin alpha is an attractive alternative because it requires less frequent injections. Iron deficiency is a major cause of anemia that is resistant to erythropoietin or darbepoetin alpha. Although oral iron is effective in some patients, many children, especially those receiving hemodialysis, require intravenous iron to replenish their iron stores. Both acute dosing and chronic dosing of intravenous iron are effective in pediatric patients.

Prevalence of anemia in erythropoietin-treated pediatric as compared to adult chronic dialysis patients

BACKGROUND

Recent guidelines recommend a target hemoglobin range of 11 to 12 g/dL in pediatric and adult dialysis patients. We compared anemia prevalence in United States Medicare pediatric and adult dialysis patients.

METHODS

Prevalent hemodialysis patients (0 to 19 years, pediatric: N= 1692; adult: N= 352,291) and peritoneal dialysis patients (pediatric: N= 597; adult: N= 39,136) treated with recombinant human erythropoietin (rHuEPO) from 1996 to 2000 were selected. Mean annual hemoglobin values were calculated by modality, age, sex, and race.

RESULTS

Among hemodialysis patients, mean annual hemoglobin values less than 11 g/dL were present in pediatric and adult patients during 54.1% versus 39.8% patient years, respectively (P < 0.0001); for peritoneal dialysis patients, 69.5% versus 55.1% (P < 0.0001). Mean hemoglobin values increased over time and were 11.2, 11.5, 10.8, and 11.2 g/dL for pediatric and adult hemodialysis and peritoneal dialysis patients, respectively, in 2000. Pediatric hemodialysis patients received intravenous iron less frequently than adults (66.3% vs. 82.5% patient years; P < 0.0001).

CONCLUSION

Hemoglobin values in rHuEPO-treated pediatric dialysis patients lagged behind those of adult patients, with pediatric patients achieving target hemoglobin values only a minority of the time (45.9% and 30.5% patient years, respectively, for hemodialysis and peritoneal dialysis). Trends show recent improvement in anemia treatment of children on dialysis. Still, further attention to and analysis of rHuEPO and iron therapy in pediatric dialysis patients is warranted.

Catch-up growth with normal parathyroid hormone levels in chronic renal failure

The optimum range for parathyroid hormone (PTH) levels in children with chronic renal failure (CRF) remains undefined. We aimed to determine growth velocity in children with CRF managed with normal PTH levels. We performed a retrospective case note review of 99 children (77 boys), with a glomerular filtration rate (GFR) <41 ml/min per 1.73 m(2), who had at least 2 years of 3-monthly follow-up. The age range at entry was 0.5-6.0 years; data collection was continued until 10 years of age or the commencement of growth hormone or renal replacement therapy. The median GFR was 22 ml/min per 1.73 m(2); over the study period mean serum calcium and phosphate levels were approximately equal to the mid-point of the respective normal ranges. Median PTH levels were equal to the upper limit of the normal range. Height standard deviation score (Ht SDS) at entry was -1.73. During the study period the overall mean change in Ht SDS was +0.3, significantly greater than the no change expected of a normal population ( P=0.004). The median dose of calcium carbonate was 150 mg/kg per day and 1-alpha calcidol 0.015 microg/kg per day. The growth rate was independent of all parameters, including age, PTH levels, the use of enteral feeds, and 1-alpha calcidol prescription. Our results indicate that catch-up growth can occur in infants and children with CRF when medical therapy is aimed at normalizing PTH levels.

Risk factors for cardiovascular disease in children on maintenance dialysis

Cardiovascular disease mortality is high in children on maintenance dialysis, accounting for about 25% of patient deaths. Cardiovascular-related mortality rates for children on dialysis are higher than for children with successful kidney transplants. Data on the long-term consequences of risk factors for cardiovascular disease are lacking for pediatric end-stage renal disease patients. This article reviews pediatric data pertaining to the following risk factors: anemia, hypertension, hyperlipidemia, left ventricular hypertrophy, abnormal calcium-phosphorus metabolism, and hyperhomocysteinemia. The potential relationship of end-stage renal disease to the etiology of several functional disorders of the cardiovascular system is discussed. Clinical studies are needed to assess the prevalence of cardiovascular disease and of cardiovascular disease risk factors in the pediatric end-stage renal disease population. Possible preventive and therapeutic guidelines need to be developed for at-risk children on maintenance dialysis.

Growth retardation in children with chronic renal failure

Growth retardation is a major obstacle to full rehabilitation of children with chronic renal failure (CRF). Several factors have been identified as contributors to impaired linear growth and they include protein and calorie malnutrition, metabolic acidosis, growth hormone resistance, anemia, and renal osteodystrophy. Although therapeutic interventions such as the use of recombinant human growth hormone, recombinant human erythropoietin, and calcitriol have made substantial contributions, the optimal therapeutic strategy remains to be defined. Indeed, growth failure persists in a substantial proportion of children with renal failure and those treated with maintenance dialysis. In addition, the increasing prevalence of adynamic lesions of renal osteodystrophy and its effect on growth have raised concern about the continued generalized use of calcitriol in children with CRF. Recent studies have shown the critical roles of parathyroid hormone-related protein (PTHrP) and the PTH/PTHrP receptor in the regulation of endochondral bone formation. The PTH/PTHrP receptor mRNA expression has been shown to be down-regulated in kidney and growth plate cartilage of animals with renal failure. Differences in the severity of secondary hyperparathyroidism influence not only growth plate morphology but also the expression of selected markers of chondrocyte proliferation and differentiation in these animals. Such findings suggest potential molecular mechanisms by which cartilage and bone development may be disrupted in children with CRF, thereby contributing to diminished linear growth.

Long-term effects of recombinant human erythropoietin therapy on growth hormone secretion in uremic patients undergoing peritoneal dialysis

Recombinant human erythropoietin (rhEPO) is being successfully used for the treatment of uremic anemia. Short-term studies have proved that correction of anemia with rhEPO therapy is accompanied by several changes in growth hormone (GH) secretion in uremic patients. The present study aimed to assess the influence of long-term rhEPO therapy on baseline and stimulated GH concentrations in a group of uremic patients undergoing continuous ambulatory peritoneal dialysis (CAPD). Seven well-nourished and clinically stable CAPD patients were studied. Ten normal subjects were studied as controls. GH responses to direct pituitary stimulation with GH-releasing hormone (GHRH) (100 microg intravenously [i.v.]) and indirect hypothalamic stimulation with insulin-induced hypoglycemia (0.1 U/kg body weight i.v.) and clonidine (0.15 mg/m2 orally), were assessed before and after 3, 6, and 12 months of subcutaneously administered rhEPO therapy. After rhEPO administration, an increase of the hemoglobin concentration was observed in all patients and maintained at about 12 g/dL throughout the study period. rhEPO therapy did not induce any significant change in baseline concentrations of GH and insulin-like growth factor I. Correction of the anemia was accompanied by a clear increase in the area under the curve (AUC) and the area above the baseline (AAB) of GH secretion in response to GHRH stimulation. These changes were statistically significant after 3 and 6 months of therapy, although at 12 months no significant differences in relation to pretreatment values could be observed. rhEPO treatment was associated with a progressive decrement in the GH AUC and AAB in response to hypoglycemic challenge, reaching statistically significant values at months 6 and 12. On the other hand, compared with the control group, GH responses to clonidine were blunted at the start of the study in CAPD patients, and rhEPO therapy was not accompanied by any modification. In conclusion, long-term treatment with rhEPO in CAPD patients is associated with complex and profound effects on somatotrope cell function, characterized by diverse effects on GH responses to stimuli that release GH through different mechanisms. Some of these rhEPO-induced alterations in somatotrope function are dependent on the duration of treatment.

Management of end-stage renal disease in children

OBJECTIVE

To review the medical literature on management of end-stage renal disease (ESRD) and its complications in the pediatric patient.

DATA SOURCES AND STUDY SELECTION

MEDLINE searches (1970-1997) of the English-language literature. Clinical trials and reviews of drug therapy management were included, and bibliographies were reviewed for relevant articles.

DATA SYNTHESIS

Principles of renal replacement therapy in children have been expanded to include maintenance of fluid and electrolyte balance and to manage the complications of ESRD in children. Types of renal replacement and their complications are reviewed. Complications of ESRD are reviewed with emphasis on drug therapy management of anemia of chronic renal failure, growth retardation, and hypertension. A discussion of the use of vitamins and supplements to maintain bone and mineral homeostasis is provided, and specific recommendations for vaccination of children with ESRD are given.

CONCLUSIONS

Children with end-stage renal failure present a unique challenge to the pharmacist. Renal replacement therapy for children with ESRD involves some form of dialysis and an intensive medication regimen. Complications must be treated with appropriate drug therapy. Drug therapy must be monitored closely for dosage adjustment, clinical response, drug interactions, and toxicity. Patients and families must receive continuous education and follow-up to encourage compliance. The pharmacist must work closely with the healthcare team to optimize drug therapy and improve patient education and compliance.

Short dialyzed children respond less to growth hormone than patients prior to dialysis. German Study Group for Growth Hormone Treatment in Chronic Renal Failure

Recombinant human growth hormone (rhGH) is a new treatment modality for short children with chronic renal failure (CRF) prior to and during dialysis. It is difficult to analyze whether dialysis patients respond less to rhGH than children with CRF on conservative treatment because they are older and often in a pubertal age range. One hundred and eight patients were treated with 28-30 IU rhGH/kg per week for at least 1 year. We analyzed the growth response to rhGH in 56 prepubertal patients aged less than 10 years at the start of rhGH treatment; 38 children with a mean age of 6.5 +/- 2.4 years were on conservative treatment (CT) and 18 patients with a mean age of 6.5 +/- 2 years on dialysis treatment (D). Mean height velocity was 4.9 +/- 2.3 cm/year in children on CT and 4.6 +/- 1.8 cm/year in children on D. During the 1st treatment year, height velocity was 9.5 +/- 3.8 cm/year in CT patients and 7.3 +/- 1.3 cm/year in D patients (P < 0.05). The change in height was +1.1 +/- 0.8 standard deviation (SD) in CT patients and +0.5 +/- 0.4 SD in D patients (P < 0.005). During the 2nd treatment year, the change in height was again greater in CT patients (0.5 +/- 0.4 SD vs. 0.2 +/- 0.4 SD; P < 0.05). The difference in height velocity and change in height standard deviation score was also significant when a subgroup of patients was matched for sex, age, height. Height velocity and the change in height velocity during rhGH treatment were not correlated with residual renal function, the degree of anemia, or metabolic acidosis. We conclude that short children on D respond less to rhGH than short children on CT, indicating a greater insensitivity to rhGH during D treatment.