Elevated Erythropoietin Concentrations Research Articles

Low erythropoietin levels predict faster renal function decline in diabetic patients with anemia: a prospective cohort study

Elevated erythropoietin (EPO) levels have been reported to predict poor survival in various populations including diabetic patients. However, data regarding its impact on renal outcomes are scarce. We conducted a single-center, prospective cohort study of 339 type 2 diabetic patients with anemia. The primary outcome was the estimated glomerular filtration rate (eGFR) slope for two years. We performed multiple linear regression and restricted cubic spline analyses to assess the association of serum EPO levels with the renal outcome. Chronic kidney disease (CKD) was defined as eGFR <60 mL/min/1.73 m2 or urine albumin-to-creatinine ratio >30 mg/g creatinine. Median baseline EPO and eGFR level were 14.4 IU/L and 53 mL/min/1.73 m2, respectively. Inappropriately low EPO levels were observed in 73% of anemic patients and 59% of anemic patients even without CKD, suggesting that EPO deficiency precedes the onset of CKD in diabetes mellitus. Multivariable analysis revealed that iron status and hemoglobin levels were major determinants of EPO levels. Median eGFR slope was −1.3 mL/min/1.73 m2/year. We found that low EPO levels, but not low hemoglobin levels, were associated with a faster decline in eGFR, independent of clinically relevant factors. The eGFR decline was steeper, particularly when the EPO level was below the upper limit of normal. Lower EPO concentrations were associated with rapid eGFR decline, especially in patients with iron deficiency (P for interaction = 0.01). Relative EPO deficiency should be considered as a culprit in anemia of unknown etiology in diabetic patients, even those without CKD. Low EPO levels, especially when accompanied by poor iron status, are predictive of rapid loss of renal function.

Genetic basis of congenital erythrocytosis.

Congenital Erythrocytosis (CE) represents a rare and heterogeneous clinical entity. It is caused by deregulated erythropoiesis where red blood cell overproduction results in elevated hemoglobin and hematocrit levels. CE may either be primary or secondary to elevated erythropoietin concentrations. The only known form of primary CE is caused by mutations in the EPOR gene. Secondary CE can be a consequence of tissue hypoxia, being caused by congenital defects such as hemoglobin variants with increased oxygen affinity, due to mutations in the α- or β-globin genes (HBB, HBA2, HBA1), or due to mutations in the BPGM gene. Secondary CE can also result from defects in the components of the oxygen-sensing pathway (PHD2, HIF2α and VHL). The family history and the quantification of serum EPO are mandatory to define the best diagnostic strategy regarding molecular studies. Based upon the serum EPO level, P50 and familial data, it is possible to establish a diagnostic algorithm. Despite recent important discoveries in the molecular pathogenesis of CE, in about 70% of the patients the genetic causes remain to be identified. Clinical data on patients suffering from CE are sparse. This fact is conditional upon the effective way to predict the disease evolution, the establishment of the best management and the genetic counselling. The number and phenotypic variability of patients that remain without an identified etiology suggest that other genes have to be implicated. Studies by next generation sequencing methodologies are already being performed and it is expected the identification of other genes involved in the pathophysiology of the CE.

Secondary polycythaemia associated with high plasma erythropoietin concentrations in a dog with a necrotising pyelonephritis

An 11-year-old mixed breed dog was presented with anorexia, apathy and intermittent macrohaematuria, absolute polycythaemia (packed cell volume, 80 per cent; red blood cell, 12.2 x 10(6)/microl) and elevated erythropoietin concentrations. A renal mass was detected by ultrasonography and, following total nephrectomy, diagnosed as necrotising pyelonephritis. After surgery, the haematological parameters and erythropoietin values returned to normal, suggesting that the pyelonephritis was the cause of the polycythaemia. While secondary polycythaemia because of a non-neoplastic condition of the kidneys occasionally occurs in human beings, it has only extremely rarely been reported in dogs. This is the first case report of a unilateral pyelonephritis causing secondary polycythaemia in a dog.

Oxygen Sensing-From Bedside to Bench: A Family with Erythrocytosis Establishes a Role for Prolyl Hydroxylase Domain Protein 2 in Oxygen Homeostasis. Proc National Acad Sci U S A 103: 654-659, 2006.

Oxygen Sensing-From Bedside to Bench: A Family with Erythrocytosis Establishes a Role for Prolyl Hydroxylase Domain Protein 2 in Oxygen Homeostasis. Proc National Acad Sci U S A 103: 654-659, 2006.

Erythropoietin Concentrations and Neurodevelopmental Outcome in Preterm Infants

Erythropoietin therapy is effective in decreasing transfusions to varying degrees in preterm infants. Recent animal studies using erythropoietin doses to achieve serum concentrations > 1000 mU/mL report neuroprotective effects. We evaluated the relationship between erythropoietin concentrations and neurodevelopmental outcome in extremely low birth weight infants. Preterm infants who weighed < or = 1000 g at birth were randomly assigned to erythropoietin (400 U/kg 3 times per week) or placebo/control. Therapy was initiated by 4 days after birth and continued through the 35th postmenstrual week. All infants received supplemental parenteral and enteral iron. Peak serum erythropoietin concentrations were obtained every 2 weeks. Follow-up evaluation included anthropometric measurements, Bayley scales of mental and psychomotor development, neurologic examination, and determination of overall neurodevelopmental impairment. Data were collected at 18 to 22 months' corrected age by certified examiners who were masked to the treatment group. Analyses were performed to identify correlations between erythropoietin concentrations and outcomes. Sixteen extremely low birth weight infants were enrolled; 1 infant died at 2 weeks (placebo/control), and 15 had erythropoietin concentrations measured (7 erythropoietin, 8 placebo/control). Peak erythropoietin concentrations were significantly different between groups during the study (erythropoietin: 2027 +/- 1464 mU/mL; placebo/control: 26 +/- 11 mU/mL). Before follow-up, 3 infants died (1 erythropoietin, 2 placebo/control), and 12 were available for follow-up (6 erythropoietin, 6 placebo/control). At 18 to 22 months' follow-up, none of the erythropoietin recipients and 2 of the placebo/control infants had Mental Development Index scores < 70. Erythropoietin recipients had Mental Development Index scores of 96 +/- 11, and placebo/control infants had Mental Development Index scores of 78 +/- 7. Psychomotor Development Index scores were similar between groups (87 +/- 13 vs 80 +/- 7). There were no differences between groups with respect to anthropometric measurements. Two of 6 infants in the erythropoietin group and 4 of 6 infants in the placebo/control group had some form of neurodevelopmental impairment. Posthoc analysis showed that infants with erythropoietin concentrations > or = 500 mU/mL had higher Mental Development Index scores than infants with erythropoietin concentrations < 500 mU/mL. Erythropoietin concentrations did not correlate with Psychomotor Development Index or overall incidence of neurodevelopmental impairment; however, infants with elevated erythropoietin concentrations had higher Mental Development Index scores than those with lower erythropoietin concentrations. Close follow-up of infants who are enrolled in large, multicenter, high-dose erythropoietin studies is required to determine whether a correlation exists between elevated erythropoietin concentrations and improved neurodevelopmental outcome.

Selectively crosslinked hyaluronic acid hydrogels for sustained release formulation of erythropoietin

A novel sustained release formulation of erythropoietin (EPO) was developed using hyaluronic acid (HA) hydrogels. For the preparation of HA hydrogels, adipic acid dihydrazide grafted HA (HA-ADH) was synthesized and analyzed with (1)H NMR. The degree of HA-ADH modification was about 69%. EPO was in situ encapsulated into HA-ADH hydrogels through a selective cross-linking reaction of bis(sulfosuccinimidyl) suberate (BS(3)) to hydrazide group (pK(a) = 3.0) of HA-ADH rather than to amine group (pK(a) > 9) of EPO. The denaturation of EPO during HA-ADH hydrogel synthesis was drastically reduced with decreasing pH from 7.4 to 4.8. The specific reactivity of BS(3) to hydrazide at pH = 4.8 might be due to its low pK(a) compared with that of amine. In vitro release of EPO in phosphate buffered saline at 37 degrees C showed that EPO was released rapidly for 2 days and then slowly up to 4 days from HA-ADH hydrogels. When the hydrogels were dried at 37 degrees C for a day, however, longer release of EPO up to 3 weeks could be demonstrated. According to in vivo release test of EPO from HA-ADH hydrogels in SD rats, elevated EPO concentration higher than 0.1 ng/mL could be maintained from 7 days up to 18 days depending on the preparation methods of HA-ADH hydrogels. There was no adverse effect during and after HA-ADH hydrogel implantation.

Detection of erythropoietin in amniotic fluid

To investigate the concentrations of amniotic fluid erythropoietin in normal and risk pregnancies. The concentrations of erythropoietin were measured in 150 samples of amniotic fluid. The samples were obtained by amniocentesis and amniotomia and were analysed using an enzyme-linked immunosorbent assay (ELISA). Results were available within 6 hours. The intra-assay variation was 6.4%, the inter-assay variation 7.2%. The range of erythropoietin concentration in all samples was between 0.23 and 80 U/L and in a defined group of normal pregnancies between 1.20 and 6.53 U/L (10%-90% percentile). Correlation was found between the concentration of erythropoietin and maternal hypertension (p = 0.0159), amnion infection syndrome in combination with premature birth (p = 0.0593), fetal growth retardation (p = 0.784), and base-excess (p = 0.0487). Elevated erythropoietin concentrations were found in a defined risk group with Apgar scores below 7 after 1 minute (p = 0.072) and after 5 minutes (p = 0.0037). There is a connection between postpartal transfer to the intensive-care unit and elevated erythropoietin concentrations (p = 0.073). No influence is exercised by the child's sex on the concentration of erythropoietin. No significant connection was found between the level of erythropoietin and smoking during pregnancy, volume of amniotic fluid and maturity at birth. A critical erythropoietin concentration could be postulated at 12 U/L. Children with higher levels showed heavy and severe disorders. Elevated erythropoietin levels in amniotic fluid indicate prolonged fetal hypoxaemia. Using the ELISA-technique a rapid prepartal determination of such situations is possible and might be helpful in the clinical procedure.

Rise in erythropoietin concentrations in experimental Trypanosoma congolense infection of calves.

A bioassay was used to measure erythropoietin (EPO) concentrations in calves with haemorrhagic anaemia due to blood loss and in calves with anaemia due to Trypanosoma congolense infection. The bioactivity of EPO was measured in the assay by its stimulatory effect on 125I-deoxyuridine incorporation in spleen cells from phenylhydrazine-treated mice. Erythropoietin concentrations in blood-volume-depleted calves were elevated 6 h after blood loss, maximal (1225 mU/ml) at 33 h and below detection limits at 72 h. Reticulocytes (0.05 +/- 0.1%) appeared in blood by 72 h, peaked at 120 h and disappeared from the circulation by 7 days after bleeding. The packed cell volume (PCV) started increasing at 120 h and reached near pre-bleeding values by 14 days. In T. congolense-infected calves, parasites were first detected in the peripheral blood 12 days post-infection (dpi). Parasitaemia peaked (5 x 10(5) trypanosomes/ml of blood) at 15-18 dpi and, thereafter, several waves of parasitaemia were observed, but the peaks gradually diminished. Undiluted plasma from T. congolense-infected calves suppressed 125I-deoxyuridine incorporation into spleen cells from 13 dpi onwards. The suppressive effect of plasma was partly negated by five-fold dilution, which made possible the detection of increased EPO concentrations during the acute and chronic stages of the anaemia. The highest EPO peaks, reaching 2300 mU/ml in one calf, were detected during the chronic stage of the infection. At 15-39 dpi, there was a transient bone-marrow erythropoietic response characterized by an increase in mean corpuscular volume and a decrease in mean corpuscular haemoglobin concentration but with few reticulocytes (0.4%). However, from 76 dpi onwards, this response waned despite low PCV and elevated EPO concentrations. These results suggest that there is an ineffective erythroid response in the face of elevated EPO concentrations during bovine trypanosomiasis. The negative effect of plasma and serum from trypanosome-infected calves on the in-vitro bioactivity of EPO suggests the presence of inhibitory factors.

Erythrocytosis after renal transplantation. The response to theophylline treatment.

Erythrocytosis was found in 20 out of 127 patients who underwent renal transplantation (15.7%). Four were found to have elevated erythropoietin concentrations (139.7 +/- 22.0 microns/ml) and 7 had normal levels (52.3 +/- 84 microns/ml (normal -60). The growth of erythroid CFUs was found to be normal in all patients. Theophylline treatment was given to 11 patients. The patients were divided into 3 groups according to their response: (1) patients with high erythropoietin levels whose hematocrit decreased from 59.6% to 46.3% within 2 weeks of treatment in parallel with a fall in erythropoietin; (2) patients with normal erythropoietin levels in whom theophylline therapy reduced the hematocrit from 58.7% to 47.2%; and (3) patients in whom theophylline had no effect on their erythrocytosis. We conclude that erythrocytosis after renal transplantation is a heterogenous condition and that several mechanisms are involved. In some patients, high erythropoietin levels or high sensitivity to erythropoietin are associated with the erythrocytosis. Theophylline therapy is beneficial in more than 50% of the cases.

Perioperative plasma erythropoietin levels in hip arthroplasty.

To examine the influence of intra- and postoperative blood loss and operative trauma on erythropoietin (EPO) production we studied patients undergoing endoprosthetic surgery of the hip. Immunoreactive plasma EPO was determined in ten patients (seven male, three female, aged 39-68 years), undergoing surgery for hip arthroplasty (n = 8) or revision hip arthroplasty (n = 2). EPO levels had already been determined during preoperative autologous deposit, thus allowing direct comparison between EPO response to blood loss alone and the response to blood loss and operative trauma. Perioperative blood loss amounted to 1720 (480-8100) ml (median, range). The hemoglobin concentration decreased from 12.4 (10.6-14.0) g/dl (median, range) before the operation to 10.0 (9.3-12.3) g/dl 2 h after the operation. Thereafter, the hemoglobin concentration increased slowly due to transfusion and erythropoiesis and was not significantly different (p < 0.05) from the preoperative value on the seventh postoperative day. The EPO concentration was preoperatively 26 (11-28) mU/ml and increased 2 h after the end of the operation, reaching a peak of 64 (45-104) mU/ml at 24 h. This peak was followed by a plateau at lower, but still elevated levels. The EPO concentration remained significantly elevated above the preoperative value on the seventh postoperative day. Plasma EPO concentrations showed an adequate response to postoperative anemia compared with the time course after autologous donation. In the early postoperative phase, they do not seem to be appreciably influenced by the neuroendocrine response to trauma, by mediators of inflammation, or by the postoperative catabolic state. The slightly elevated EPO concentration in the late postoperative phase indicates that factors other than anemia may contribute to EPO production at this time.

Cord blood erythropoietin in relation to different markers of fetal hypoxia

To investigate the relationship between erythropoietin concentration in umbilical venous blood and clinical signs of fetal hypoxia.We measured erythropoietin concentrations in umbilical venous blood from 200 consecutively born neonates using an enzyme-linked immunosorbent assay (ELISA) with two monoclonal antibodies. Results were available within 6 hours. Inter-assay variation was 8.5% and the mean intra-assay variation was 14.2%.Using a multiple regression analysis, we found that the erythropoietin concentration correlated significantly (P < .01) with fetal growth retardation and umbilical acidosis but not with gestational age, meconium-stained amniotic fluid (AF), abnormal fetal heart rate (FHR) pattern, or Apgar score at 5 minutes. Median erythropoietin concentrations were 25.1 mU/mL in infants with no risk factors or complications during pregnancy and delivery (n = 19), 25.8 mU/mL after complicated pregnancy (n = 95), 50.6 mU/mL with meconium-stained AF (n = 12), 44.7 mU/mL with abnormal FHR pattern (n = 40), 47.8 mU/mL with both stained AF and abnormal FHR pattern (n = 10), and 72.6 mU/mL with umbilical acidosis (n = 24). The median erythropoietin concentration increased significantly with decreasing pH and with increasing base deficit in umbilical arterial blood. The erythropoietin concentration in umbilical venous blood (cutoff value 50 mU/mL) discriminated between infants with no clinical signs of fetal hypoxia and those with umbilical acidosis with a sensitivity of 75% and a specificity of 90%.Elevated erythropoietin concentrations in umbilical venous blood indicate prolonged fetal hypoxia. The ELISA technique might be a useful tool for determining the exact time course of erythropoietin concentrations in fetal hypoxia.