Red blood cell precursor mass as an independent determinant of serum erythropoietin level.

in Blood (1998), 91(6), 2139-45

Serum erythropoietin (sEpo) concentration is primarily related to the rate of renal production and, under the stimulus of hypoxia, increases exponentially as hemoglobin (Hb) decreases. Additional factors ... [more ▼]

Serum erythropoietin (sEpo) concentration is primarily related to the rate of renal production and, under the stimulus of hypoxia, increases exponentially as hemoglobin (Hb) decreases. Additional factors, however, appear to influence sEpo, and in this work, we performed studies to evaluate the role of the red blood cell precursor mass. We first compared the relationship of sEpo with Hb in patients with low versus high erythroid activity. The first group included 27 patients with erythroid aplasia or hypoplasia having serum transferrin receptor (sTfR) levels < 3 mg/L (erythroid activity < 0.6 times normal), while the second one included 28 patients with beta-thalassemia intermedia having sTfR levels > 10 mg/L (erythroid activity > 2 times normal). There was no difference between the two groups with respect to Hb (8.3 +/- 1.6 v 8.0 +/- 1.3 g/dL, P > .05), but sEpo levels were notably higher in patients with low erythroid activity (1,601 +/- 1,542 v 235 +/- 143 mU/mL, P < . 001). In fact, multivariate analysis of variance (ANOVA) showed that, at any given Hb level, sEpo was higher in patients with low erythroid activity (P < .0001). Twenty patients undergoing allogeneic or autologous bone marrow transplantation (BMT) were then investigated. A marked increase in sEpo was seen in all cases at the time of marrow aplasia, disproportionately high when compared with the small decrease in Hb level. Sequential studies were also performed in five patients with iron deficiency anemia undergoing intravenous (IV) iron therapy. Within 24 to 72 hours after starting iron treatment, marked decreases in sEpo (up to one log magnitude) were found before any change in Hb level. Similar observations were made in patients with megaloblastic anemia and in a case of pure red blood cell aplasia. These findings point to an inverse relationship between red blood cell precursor mass and sEpo: at any given Hb level, the higher the number of red blood cell precursors, the lower the sEpo concentration. The most likely explanation for this is that sEpo levels are regulated not only by the rate of renal production, but also by the rate of utilization by erythroid cells. [less ▲]

Defective iron supply for erythropoiesis and adequate endogenous erythropoietin production in the anemia associated with systemic-onset juvenile chronic arthritis.

in Blood (1996), 87(11), 4824-30

Systemic-onset juvenile chronic arthritis (SoJCA) is associated with high levels of circulating interleukin-6 (IL-6) and is frequently complicated by severe microcytic anemia whose pathogenesis is unclear ... [more ▼]

Systemic-onset juvenile chronic arthritis (SoJCA) is associated with high levels of circulating interleukin-6 (IL-6) and is frequently complicated by severe microcytic anemia whose pathogenesis is unclear. Therefore, we studied 20 consecutive SoJCA patients with hemoglobin (Hb) levels <12 g/dL, evaluating erythroid progenitor proliferation, endogenous erythropoietin production, body iron status, and iron supply for erythropoiesis. Hb concentrations ranged from 6.5 to 11.9 g/dL. Hb level was directly related to mean corpuscular volume (r = .82, P < .001) and inversely related to circulating transferrin receptor (r = -.81, P < .001) suggesting that the severity of anemia was directly proportional to the degree of iron-deficient erythropoiesis. Serum ferritin ranged from 18 to 1,660 microgram/L and was unrelated to Hb level. Bone marrow iron stores wore markedly reduced in the three children investigated, and they also showed increased serum transferrin receptor and normal-to-high serum ferritin. All 20 patients had elevated IL-6 levels and normal in vitro growth of erythroid progenitors. Endogenous erythropoietin (epo) production was appropriate for the degree of anemia as judged by both the observed to predicted log (serum epo) ratio 10.95 +/- 0.12) and a comparison of the serum epo-Hb regression found in these subjects with that of thalassemia patients. Multiple regression analysis showed that serum transferrin receptor was the parameter most closely related to hemoglobin concentration: variation in circulating transferrin receptor explained 61% of the variation in Hb level (P < .001). In 10 severely anemic patients, amelioration of anemia following intravenous iron administration resulted in normalization of serum transferrin receptor. Defective iron supply to the erythron rather than blunted epo production is the major cause of the microcytic anemia associated with SoJCA. A true body-iron deficiency caused by decreased iron absorption likely complicates long-lasting inflammation in the most anemic children, and this can be recognized by high serum transferrin receptor levels. Although oral iron is of no benefit, intravenous iron saccharate is a safe and effective means for improving iron availability for erythropoiesis and correcting this anemia. Thus, while chronically high endogenous IL-6 levels do not appear to blunt epo production, they are probably responsible for the observed abnormalities in iron metabolism. Anemia of chronic disease encompasses a variety of anemic conditions whose peculiar features may specifically correlate with the type of cytokine(s) predominantly released. [less ▲]

Relationship between transfusion regimen and suppression of erythropoiesis in beta-thalassaemia major.

in British Journal of Haematology (1995), 89(3), 473-8

In the management of beta-thalassaemia major, different transfusion schemes are employed with baseline haemoglobin levels ranging from 8 to over 12 g/dl. We studied the relationship between transfusion ... [more ▼]

In the management of beta-thalassaemia major, different transfusion schemes are employed with baseline haemoglobin levels ranging from 8 to over 12 g/dl. We studied the relationship between transfusion regimen and suppression of erythropoiesis in 52 patients with beta-thalassaemia major whose mean pretransfusion haemoglobin levels ranged from 8.6 to 10.9 g/dl. Multiple, regression analysis showed that serum transferrin receptor was the parameter more closely related to mean pretransfusion haemoglobin (r = -0.77, P < 0.001). As measured through serum transferrin receptor, erythroid activity was 1-2 times normal for pretransfusion haemoglobin levels between 10 and 11 g/dl. 1-4 times normal for levels from 9 to 10 g/dl, and 2-6 times normal for levels from 8.6 to 9 g/dl. Mean pretransfusion haemoglobin was also inversely related to serum erythropoietin (r = -0.72, P < 0.001), whereas it showed no or a weak relationship with Hb F, reticulocyte count, or circulating nucleated red cell count. This study suggests that serum transferrin receptor is a reliable indicator of suppression of erythropoiesis in beta-thalassaemia major. On the basis of our findings, pretransfusion haemoglobin values of < or = 9 g/dl should be adopted with caution, because these levels can be associated with an insufficient inhibition of erythroid marrow expansion. However, a transfusion programme, with a baseline haemoglobin of 9-10 g/dl, may provide enough suppression of erythropoiesis and allow a reduction in blood consumption as compared with the classic hyper- or supertransfusion schemes. Since fixed haemoglobin levels may not be the best target for transfusion treatment in all thalassaemic patients, assay of serum transferrin receptor may be helpful for individualizing the transfusion regimens. [less ▲]

Use of recombinant human erythropoietin after bone marrow transplantation in pediatric patients with acute leukemia: effect on erythroid repopulation in autologous versus allogeneic transplants.

in Bone Marrow Transplantation (1994), 13(4), 403-10

We carried out a pilot study on the use of recombinant human erythropoietin (rHuEPO) in children undergoing allogeneic or mafosfamide-purged autologous BMT for ALL or AML. rHuEPO was administered ... [more ▼]

We carried out a pilot study on the use of recombinant human erythropoietin (rHuEPO) in children undergoing allogeneic or mafosfamide-purged autologous BMT for ALL or AML. rHuEPO was administered intravenously at a dose of 75 U/kg/day for 30 days after transplant. Ten rHuEPO-treated patients receiving allogeneic BMT and 10 given autologous BMT were compared with 15 allogeneic and 10 autologous historical controls. Endogenous EPO production was appropriate for the degree of anemia after autologous BMT. In these patients, rHuEPO did not accelerate erythroid repopulation and did not modify transfusion requirements. With allogeneic BMT, erythroid marrow activity increased faster in patients given rHuEPO than in controls and resulted in higher red cell production, the mean reticulocyte count on day +30 being 187 +/- 51 x 10(9)/l in treated patients versus 107 +/- 63 x 10(9)/l in controls (p < 0.01). The total number of RBC units administered was 1.7 +/- 1.3 in the rHuEPO group versus 5.1 +/- 3.0 in the control group (p < 0.001). The total number of platelet transfusions was 4.0 +/- 2.3 for patients given allogeneic BMT and receiving rHuEPO versus 8.4 +/- 6.8 for historical controls (p < 0.05) whereas it was similar in rHuEPO-treated and control autologous BMT patients.(ABSTRACT TRUNCATED AT 250 WORDS) [less ▲]

Accelerated erythroid repopulation with no stem-cell competition effect in children treated with recombinant human erythropoietin after allogeneic bone marrow transplantation.

in British Journal of Haematology (1993), 84(4), 752-4

We carried out a pilot study on the use of recombinant human erythropoietin (rHuEPO) to accelerate erythropoietic engraftment in paediatric patients undergoing allogeneic BMT. rHuEPO was administered ... [more ▼]

We carried out a pilot study on the use of recombinant human erythropoietin (rHuEPO) to accelerate erythropoietic engraftment in paediatric patients undergoing allogeneic BMT. rHuEPO was administered intravenously at a dose of 75 U/kg per day for 30 d after transplant. Erythroid repopulation, evaluated sequentially through the serum transferrin receptor, was faster in 15 patients receiving rHuEPO than in 16 historical controls (P = 0.0003). This faster erythroid engraftment resulted in a reduction in the total number of red blood cell units required to reach transfusion independence (2.7 +/- 1.2 v 4.2 +/- 2.3, P = 0.027). No significant difference in leucocyte or platelet regeneration was observed. These findings indicate that rHuEPO administration can accelerate erythroid recovery after allogeneic BMT and reduce red cell transfusion requirements with no stem-cell competition effect. [less ▲]

Subcutaneous erythropoietin for treatment of refractory anemia in hematologic disorders. Results of a phase I/II clinical trial.

in Blood (1992), 79(1), 29-37

We have used recombinant human erythropoietin (rHuEPO) in a phase I/II clinical trial to evaluate its ability to reverse refractory anemia in hematologic disorders. rHuEPO was administered subcutaneously ... [more ▼]

We have used recombinant human erythropoietin (rHuEPO) in a phase I/II clinical trial to evaluate its ability to reverse refractory anemia in hematologic disorders. rHuEPO was administered subcutaneously 5 days per week at escalating doses (50 to 150 U/kg per day). The aim of treatment was a hemoglobin (Hb) level greater than or equal to 10 g/dL without blood transfusion. Of 25 patients treated, 17 were evaluable, most of them with a regular need for transfusion. Eight of these had lymphoproliferative disorders (three cases of malignant lymphoma and five of monoclonal gammopathy) and were exposed to cytotoxic therapy. The other nine patients had hematopoietic stem cell disorders (four cases of myelodysplastic syndrome, three of idiopathic myelofibrosis, and two of chronic myelogenous leukemia). All patients with lymphoproliferative disorder had serum EPO levels inappropriately low for the degree of anemia, while patients with stem cell disorder showed variable values. Erythroid marrow activity was inadequate in all cases. Seven of eight patients with lymphoproliferative disorder responded to treatment maintaining Hb above 10 g/dL without transfusion. The median dose of rHuEPO required for correction of anemia was 75 U/kg. In four cases response was maintained with 50 U/kg, three times per week. There was no complete response among patients with hematopoietic stem cell disorder, although transfusion requirement was eliminated or reduced in four cases. Four patients developed functional iron deficiency during rHuEPO treatment and required iron supplementation to obtain response. Aggravation of splenomegaly was observed in two cases of myeloproliferative disorder. We conclude that: (1) subcutaneous administration of rHuEPO can be effective and safe in patients with lymphoproliferative disorder exposed to chemotherapy and showing inappropriate EPO response to anemia; (2) this is less likely in hematopoietic stem cell disorders, although favorable responses may be observed in occasional patients; and (3) functional iron deficiency as a cause of nonresponse to rHuEPO is frequent also in nonrenal anemia. [less ▲]

Serum erythropoietin levels during haematinic treatment

in British Journal of Haematology (1992), 82