Erythropoietin and renal transplantation

Proteinuria is a predictor of posttransplant anemia

INTRODUCTION

Posttransplant anemia (PTA) involves many factors. Although the link between the hemoglobin (Hb) levels and renal function is known, the relationship between proteinuria and PTA hemoglobin has not been widely explored. The aim of this study was to evaluate whether proteinuria was a predictor of anemia and whether erythropoietin-stimulating agent therapy was a protective factor for kidney damage among transplantation patients.

METHODS

We retrospectively examined 144 kidney transplant recipients of mean age 44.4 ± 12.3 years and a mean follow-up period of 40.5 ± 4.6 months. Exclusion criteria were age under 18 years, multiorgan transplantation, proteinuria at 6 months over 1.5 g/d, and transplant failure within the first year. Using regression models, we evaluated the potential predictive power of proteinuria at 6 months after renal transplantation for anemia as expressed by Hb levels at 1 year.

RESULTS

The frequency of patients with PTA was 38.89% at 1 year, 35.21% at 2 years, and 31.43% at 3 years. Variables with significant correlations with anemia upon univariate analysis were: proteinuria, donor age, acute rejection, estimated glomerular filtration rate, s-creatinine, and salbumin. Upon multivariate regression analysis 24-hour proteinuria and s-albumin remained independent predictors of 1-year PTA. Univariate analysis among the entire cohort showed a significant correlation between 1-year Hb and proteinuria/24 hours at 6 months (P=.007), an observation that was confirmed in the adjusted model along with recipient sex. Patients were then divided into two groups regarding treatment with erythropoiesis stimulating agents (ESA). Multivariate analysis showed that proteinuria (P=.005) was a predictor of Hb only among the group of patients who did no receive erythropoietin, whereas this relationship disappeared among the group treated with ESA.

CONCLUSIONS

These results showed that proteinuria at 6 months was a predictor of Hb levels at 1 year. Treatment of transplant patients with ESA may be a protective factor for renal endothelial damage expressed as proteinuria.

Risk factors of post renal transplant anaemia among Sudanese patients, a study in three renal transplant centres

Background

There is a relative lack of recent information about late post kidney transplantation anaemia (PTA), especially in the developing countries; data are scarce about the prevalence and risk factors of PTA. Sudan was a leading country in Africa and Arab world in kidney transplantation. The first kidney transplantation in Sudan was in 1973.

Methods

This is a cross-sectional hospital analytic study enrolling all kidney transplanted recipients following in the transplant referral clinics at Ahmed Gassim, Selma and Ibn Sina Hospitals, Khartoum/Sudan, in the period from 1/8/2010 to 1/9/2010, clinical and laboratory data were obtained from 114 patients, anaemia was defined as Hb levels of < 13 g/dl for male patients and < 12 g/dl for female patients, exclusion criteria were pregnancy, below 18 years old patients, multiple organ transplantation, and patients with less than one year from the transplantation.

Results

The study showed that 39.5% of the patients were anaemic. Univariate analysis showed that late PTA is significantly associated with not using Erythropoietin (EPO) in the pre-transplant period (p = < 0.001), history of rejection (p = 0.003), longer time from transplantation (p = 0.015), and eGFR (p < 0.0001). Multivariate analysis showed that eGFR (p = < 0.001) and not use of EPO in the pre transplant period (p < 0.001) are strong predictors of PTA. The use of Angiotensin converting enzyme inhibitors/Angiotensin receptors blockers (ACEI/ARB), immunosuppressive treatments, presence or absence of co-morbidities, donor type and donor age are not significantly associated with late PTA.

Conclusion

The study concluded that late PTA is common and under recognized. Risk factors for late PTA include renal dysfunction, history of rejection, longer duration of transplantation and not using EPO in the pre-transplant period. Renal dysfunction and not using EPO in the pre-transplant period are major predictors of late PTA.

Effect of pretransplantation hemoglobin blood concentration on renal allograft survival and function

The effect of pretransplantation hemoglobin (Hb) concentration on the outcome of kidney transplantation (KTx) was studied in 188 adult kidney transplant recipients. Patients were divided into 2 groups: high Hb (>or=10 g/dL; n=97) and low Hb (<10 g/dL; n=91). Both groups were matched for recipient sex, donor age and sex, donor-recipient blood groups, indications for kidney transplantation, and degree of sensitization. Acute rejection episodes occurred in 20 patients in the high-Hb group (20.6%) and 18 in the low-Hb group (19.8%). Antithymocyte globulin-Fresenius therapy was required in 6 patients in the high-Hb group compared with 5 patients in the low-Hb group. Infection rate, 1-year actuarial patient and graft survival, incidence of delayed and slow graft function, and number of surgical complications were comparable between groups. Compared with the low Hb group, in the high-Hb group, hospital stay was longer, creatinine concentration at 12 months post-KTx and serum glucose concentration at 6 months post-KTx were significantly higher, and pre- and posttransplantation Hb concentrations were higher. The need for post-KTx transfusions was comparable between groups. Pretransplantation Hb concentration did not affect outcome except for longer initial hospital stay and 1-year creatinine concentration.

Pathophysiology of anemia and erythrocytosis

An increasing understanding of the process of erythropoiesis raises some interesting questions about the pathophysiology, diagnosis and treatment of anemia and erythrocytosis. The mechanisms underlying the development of many of the erythrocytoses, previously characterised as idiopathic, have been elucidated leading to an increased understanding of oxygen homeostasis. Characterisation of anemia and erythrocytosis in relation to serum erythropoietin levels can be a useful addition to clinical diagnostic criteria and provide a rationale for treatment with erythropoiesis stimulating agents (ESAs). Recombinant human erythropoietin as well as other ESAs are now widely used to treat anemias associated with a range of conditions, including chronic kidney disease, chronic inflammatory disorders and cancer. There is also heightened awareness of the potential abuse of ESAs to boost athletic performance in competitive sport. The discovery of erythropoietin receptors outside of the erythropoietic compartment may herald future applications for ESAs in the management of neurological and cardiac diseases. The current controversy concerning optimal hemoglobin levels in chronic kidney disease patients treated with ESAs and the potential negative clinical outcomes of ESA treatment in cancer reinforces the need for cautious evaluation of the pleiotropic effects of ESAs in non-erythroid tissues.

Reticulocytes and their immature fraction do not detect acute rejection after kidney transplantation

BACKGROUND

Early detection of an acute rejection episode is an important problem in monitoring transplant patients. Erythropoietin (EPO) production is diminished in patients suffering from chronic renal insufficiency or acute rejection. Therefore, a decrease of reticulocyte counts and of young reticulocytes might indicate the emergence of an acute rejection episode. This pilot study examined the value of reticulocyte parameters as indicators of acute rejection episodes.

PATIENTS AND METHODS

Reticulocyte parameters were examined in 25 renal transplant patients. Initial immunosuppressants therapy was based on a combination of methylprednisolone, mycophenolatmofetil, cyclosporine and antithymocyte globulin or basiliximab, CellCept, cyclosporine, and ATG or Simulect. During the first 3 weeks after the procedure, blood samples were collected three times per week. Complete blood counts were performed on XE-2100 analyzers (Sysmex). Acute rejection was biopsy-proven.

RESULTS

Acute rejection episodes were not accompanied by significantly altered reticulocyte parameters. During the first weeks, the reticulocyte count or the immature fraction, respectively, did not differ between patients with delayed versus immediate onset of renal function: reticulocyte count 1.70 +/- 1.06% vs 1.58 +/- 1.10% and ratio of immature (high fluorescent) reticulocytes 22.8 +/- 7.9% vs 17.6 +/- 9.4%).

CONCLUSION

Reticulocyte counts and determination of the immature reticulocyte fraction were not significantly altered by an acute rejection episode. Various influences modulate the release of EPO and reaction of erythropoiesis upon an EPO stimulus.

Prevalence and Etiology of Anemia in Renal Transplant Recipients

We aimed to define the prevalence of anemia and possible causes for it in a group of renal transplant recipients. A total of 229 recipients (65 women; age 36.1 +/- 11.8 years; minimum posttransplant duration, 3 years) were included. Patients with iron, vitamin B(12), and folic acid deficiencies were excluded. Patients were grouped according to number of posttransplant years completed with functioning grafts (3, 5, or 10 years). Demographic data, donor information, HLA mismatches, acute rejection episodes, biochemical parameters, and medications received during the 3 months before transplant and at 3, 5, and 10 years posttransplant were collected retrospectively. The anemia threshold was 13 g/dL for men and 12 g/dL for women. Anemia prevalence was 41.5%, 35.3%, and 93.2% at 3, 5, and 10 years, respectively. Anemic patients had higher creatinine levels for all years. In the anemic patients, hemoglobin values were lower in the pretransplant period than at 3 and 5 years. Anemic patients had higher HLA mismatches for the same years. Three-year hemoglobin levels were positively correlated with pretransplant hemoglobin and negatively correlated with creatinine levels and HLA mismatches. Five-year hemoglobin levels were positively correlated with pretransplant hemoglobin and albumin levels. Ten-year hemoglobin levels were positively correlated with pretransplant hemoglobin and albumin values but negatively correlated with creatinine levels and HLA mismatches. The prevalence of anemia in renal transplant recipients increases in parallel with posttransplant duration. Hemoglobin levels in these patients are closely related with pretransplant hemoglobin, follow-up creatinine levels, and HLA mismatches.

Anaemia after renal transplantation

Anaemia is a frequent complication among long-term renal transplant recipients. A prevalence of approximately 40% has been reported in several studies. If renal function declines to stage 5 kidney disease, the prevalence of anaemia in kidney transplants is even higher. A positive correlation between haemoglobin concentration and creatinine clearance has been reported, which is a function of endogenous erythropoietin production by the functioning graft. Inflammation related to a retained kidney graft may cause hypo-responsiveness to erythropoietic agents once kidney transplant recipients return to dialysis. Furthermore, the use of azathioprine, mycophenolate mofetil and sirolimus may be associated with post-transplant anaemia. Along with erythropoietin deficiency, depletion of iron stores is one of the major reasons for anaemia in the kidney transplant population. The proportion of hypochromic red blood cells appears to be a useful parameter to measure iron supply and utilization as well as to estimate mortality risks in kidney transplant recipients. While anaemia is an important cardiovascular risk-factor after transplantation, our data suggest that anaemia is not associated with mortality and graft loss. Nevertheless, inadequate attention is paid so far to the management of anaemia after renal transplantation. A promising future aspect for risk reduction of cardiovascular disease includes the effect of erythropoietic agents on endothelial progenitor cells.

Post-liver-transplant anemia: etiology and management

Anemia is common after liver transplantation, with the incidence ranging from 4.3% to 28.2% depending on the criteria used to define anemia. The cause of anemia is unidentified in the majority of patients, and it is likely to be multifactorial. Immunosuppressive-medication-induced bone marrow suppression is perhaps the most common cause of unexplained anemia. Chronic blood loss, iron deficiency, hemolysis, and renal insufficiency are other potential causes of chronic anemia. Rare causes, somewhat unique to transplantation, include aplastic anemia, graft-versus-host disease (GVHD), and lymphoproliferative disease. Anemia due to immunosuppressive medication is challenging, since almost all drugs currently used for this purpose cause anemia, but the renal-sparing property of sirolimus may benefit the subgroup in which renal insufficiency is contributing to anemia. Aplastic anemia is seen in young patients transplanted for non-A, non-B, non-C, fulminant hepatic failure. It is thought to be immunologically mediated, secondary to an unknown viral infection, and is associated with a grave prognosis. GVHD is another infrequent (approximately 1% of transplant recipients) but serious cause of severe anemia that carries a dismal prognosis. Lymphoproliferative disorder, too may rarely rare cause anemia and it may respond to reduction of immunosuppression. Recipients of solid-organ transplants do not mount a significant increase in erythropoietin in response to anemia. In conclusion, though there are no data on the response of anemia to erythropoietin in liver transplant recipients, it appears to benefit other solid-organ-transplant recipients with anemia.

Evaluation of erythropoiesis and changes in serum erythropoietin concentration in cats after renal transplantation

OBJECTIVE

To investigate the clinicopathologic patterns of the erythropoietic response after renal transplantation in cats with chronic renal failure (CRF).

ANIMALS

14 cats with CRF undergoing renal transplantation.

PROCEDURE

Before and at intervals during a 6-month period after transplantation, serum creatinine and erythropoietin concentrations, Hct, erythrocyte indices, aggregate reticulocyte percentage, and iron variables were measured. Additionally, the number of transfusions administered to and any complications that developed in each cat were recorded.

RESULTS

In all cats, preoperative azotemia resolved within 6 days after renal transplantation. Two cats had a temporary increase in serum creatinine concentration secondary to an acute graft rejection episode. Anemia (defined as Hct < 28%) resolved in 10 cats 3 to 49 days after surgery. Resolution of anemia was delayed in 2 cats that had acute rejection episodes. Serum erythropoietin concentration and reticulocyte percentage were low preoperatively; values after surgery were highly variable. Compared with preoperative values, serum erythropoietin concentration increased 1 to 4 days after surgery in 11 cats; between days 5 and 58, another increase was detected in 9 cats. Serum iron concentrations were generally low before and 14 days after transplantation.

CONCLUSION AND CLINICAL RELEVANCE

The erythropoietic response was highly variable in cats after renal transplantation, but anemia typically resolved within 1 month after surgery. A delay in resolution of anemia in cats may indicate poor graft function and inadequate iron stores, suggesting the need for further evaluation for concurrent illness.

Use of recombinant human erythropoietin in kidney transplant patients with stable graft function

The purpose of this work was to determine the necessity for rhuEPO for 50 kidney transplant patients with stable graft function. We analyzed the red cell series, blood pressure, renal function, anthropometric data of the donor and recipient, proteinuria, and relationship with other factors, including immunosuppressants, angiotensin converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARB). The patients were divided into three groups depending on renal function: group A (with plasma creatinine <150 micromol/L), group B (151-250 micromol/L), and group C (>250 micromol/L). All patients were studied for 1 year. Erythropoietin use did not affect renal function, proteinuria or number of antihypertensive drugs group. The degree of renal dysfunction determined the time necessary to reach an adequate hemoglobin level (>12 g/L) and and the mean dose of weekly rhuEPO needed. The use of ACE inhibitors or ARBs increased the rhuEPO requirements in each group.

Prevalence and management of anemia in renal transplant recipients: a European survey

The TRansplant European Survey on Anemia Management (TRESAM) documented the prevalence and management of anemia in kidney transplant recipients. Data from 72 transplant centers in 16 countries were screened, involving 4263 patients who had received transplants 6 months, 1, 3 or 5 years earlier. The mean age of transplant recipients was 45.5 years at transplantation. The most common etiology was chronic glomerulonephritis. The most common comorbidities were coronary artery disease, hepatitis B/C, and type 2 diabetes. The mean hemoglobin levels before transplantation were significantly higher in the more recently transplanted recipients. At enrollment, 38.6% of patients were found to be anemic. Of the 8.5% of patients who were considered severely anemic, only 17.8% were treated with epoetin. There was a strong association between hemoglobin and graft function; of the 904 patients with serum creatinine > 2 mg/dL, 60.1% were anemic, vs. 29.0% of those with serum creatinine <or= 2 mg/dL (p < 0.01). Therapy with angiotensin-converting enzyme (ACE) inhibitors, angiotensin II receptor antagonists, mycophenolate mofetil (MMF) or azathioprine was also associated with a higher likelihood of anemia. The prevalence of anemia in the transplant recipients was remarkably high and appeared to be associated with impaired renal function and with ACE inhibitors and angiotensin II receptor antagonist use. Further studies should be carried out to interpret whether appropriate management of anemia after kidney transplantation may improve long-term outcome.

Unexpectedly high prevalence of posttransplant anemia in pediatric and young adult renal transplant recipients

BACKGROUND

Although posttransplant anemia (PTA) is recognized as a common problem in adult renal transplant recipients, few pediatric studies have been published.

METHODS

In this retrospective cohort study of 162 pediatric renal transplant recipients treated at Stanford University, the authors sought to determine the prevalence, severity, and the predictive factors of PTA. Anemia was defined as a hematocrit (HCT) level greater than 2 SD below published means for age or as erythropoietin dependency to maintain a normal HCT.

RESULTS

Sixty-seven percent of pediatric renal transplant recipients were anemic at the time of transplantation. The prevalence of anemia increased to 84.3% in the first month posttransplant. From 6 months to 60 months posttransplant, the prevalence of anemia remained high at 64.2% to 82.2%. Only 4 patients (2.5%) were never anemic. Iron depletion was detected in 19 of 26 and 23 of 23 anemic patients 12 and 60 months posttransplant, respectively. Serum erythropoietin levels were low relative to hematocrit levels in 38 of 56 anemic patients. Logistic regression at 3 months posttransplant showed that discharge hematocrit level (P < 0.0001), calcium (P = 0.0004), and cyclosporine dose (P = 0.0002) correlated with anemia. Creatinine clearance (P = 0.002) and white blood cell count (P = 0.004) correlated with anemia at 12 months posttransplant, but only creatinine clearance (P = 0.011) correlated with anemia 60 months posttransplant.

CONCLUSION

Nearly all pediatric renal transplant recipients experience PTA. However, few children less than 2 years of age were anemic during the first year posttransplant. Antirejection therapy, bone disease, iron depletion, and creatinine clearance appear to play pivotal roles in the development of PTA in children.

Mortality after kidney transplant failure: the impact of non-immunologic factors

BACKGROUND

One third of cadaveric kidney transplant recipients suffer graft loss within five years of transplantation. Non-immunologic factors that predict mortality among non-transplant patients also may be potentially modifiable risk factors for mortality among patients with transplant failure.

METHODS

Applying multivariate survival analysis to data from the United States Renal Data System, we determined the effect of immunologic or transplant related factors and non-immunologic factors on mortality in patients who initiated dialysis after kidney transplant failure in the United States between April 1995 and September 1998.

RESULTS

A total of 4741 patients were followed for a median +/- standard deviation of 15 +/- 11 months after initiation of dialysis after transplant failure. The majority of the 1016 (21%) deaths were due to cardiac (36%) or infectious (17%) causes. Patients in the following groups had an increased risk for all-cause mortality: older patients [hazard ratio (HR) = 1.04 per year, 95% confidence interval (95% CI) 1.03-1.04], women (HR = 1.31, 95% CI 1.10-1.56), patients of white race (HR = 1.94, 95% CI 1.32-2.84), patients with diabetes (HR = 1.76, 95% CI 1.43-2.16), peripheral vascular disease (HR = 1.94, 95% CI 1.54-2.43), congestive heart failure (HR = 1.26, 95% CI 1.05-1.53), drug use (HR = 2.23; 95% CI 1.08-4.60), smokers (HR = 1.35, 95% CI 1.01-1.81), first transplant recipients (HR = 1.32, 95% CI 1.02-1.69), and patients with a higher glomerular filtration rate (GFR) at dialysis initiation (HR = 1.04 per mL/min higher, 95% CI 1.02-1.06). Those with private insurance (HR = 0.67, 95% CI 0.49-0.93) and higher serum albumin (HR = 0.73 per g/dL higher, 95% CI 0.64-0.83) had a decreased risk for all-cause mortality. Acute rejection, antibody induction, donor source, duration of graft survival and the maximum attained GFR during transplantation did not predict all-cause mortality.

CONCLUSIONS

Non-immunologic factors predicted mortality among patients with transplant failure but immunologic and transplant related factors did not. Prevention, early diagnosis and treatment of co-morbid conditions and the complications of chronic kidney disease may improve the survival of patients with transplant failure.

Opportunities to improve the care of patients with kidney transplant failure

BACKGROUND

Patients initiating dialysis after a failed kidney transplant are a subgroup of chronic kidney disease (CKD) patients who have not been characterized. Exposure to immunosuppressive medications differentiates these patients from the general incident end-stage renal disease (ESRD) population.

METHODS

Data from the Health Care Financing Administration 2728 form were used to determine the hematocrit, erythropoietin use, serum albumin and glomerular filtration rate (GFR) among 4643 patients with failed kidney transplants who initiated dialysis between April 1995 and December 1998.

RESULTS

At dialysis initiation, the mean hematocrit, serum albumin and GFR were 27.5%, 3.3 g/dL, and 8.4 mL/min/1.73 m2, respectively, and only 35% of patients had received erythropoietin. In a multivariate analysis, patients <45 years, females, patients of non-White race, non-diabetic patients, hemodialysis patients and patients with a lower serum albumin had a higher odds for hematocrit <30%. Erythropoietin use was associated with female gender, White race, increased time since transplantation, being employed, peritoneal dialysis, and higher serum albumin. Patients >/=45 years and patients with diabetes or congestive heart failure had higher odds for hypoalbuminemia, while employed patients, peritoneal dialysis patients, patients with higher hematocrit and patients who had received erythropoietin had lower odds of hypoalbuminemia.

CONCLUSIONS

Despite being known to specialty physicians, patients with failed kidney transplants initiate dialysis at levels of hematocrit, serum albumin, and GFR that may be suboptimal and similar to those in the general incident ESRD population. Socioeconomic factors remain important barriers to the provision of CKD care even among these patients with established specialty physician contact. Improved CKD care could improve the outcomes of this unique subgroup of CKD patients.

Research directions: new clinical frontiers

One of the greatest remaining challenges facing nephrology research is obtaining data with detail and precision for the three large, yet "forgotten," populations that span the spectrum of kidney disease: patients with chronic renal insufficiency (CRI), peritoneal dialysis patients, and kidney transplant patients. Studies of these populations, particularly the CRI group, are hampered by the relative mobility of these patients, the lack of stringent epidemiologic or clinical definitions, and the tendency to extrapolate data from hemodialysis populations into other clinical settings. This article suggests a two-pronged approach to a research agenda: first, by recognizing the need for better data regarding the natural history of these kidney failure subsets and their comorbidities; and second, by directing greater effort at identifying rational, efficacious, and cost-effective interventions to influence their natural history positively. Specific efforts are suggested in all three populations. For patients with CRI, studies should be directed at (1) identifying high-risk patients; (2) determining methods for making optimal referrals to the nephrologist; (3) identifying and managing CRI, its complications, and its comorbid conditions; and (4) establishing processes for the smooth transition to dialysis. The peritoneal dialysis population will benefit from studies addressing the treatment of anemia and its ability to modify cardiovascular illness and quality of life. Kidney transplant studies should also focus on the identification and management of comorbid conditions, as well as the effects of various interventions on quality of life. Rational evidence-based care of these conditions, which are critically important to patients, their families, and the health care system in general, must await the conduct of well-designed prospective observational and interventional trials.