Reticulocyte Response Research Articles

Reticulocyte parameters and hemoglobin F production in sickle cell disease patients undergoing hydroxyurea therapy

Hemoglobin F (HbF) is an effective inhibitor of HbS polymerization. Hydroxyurea (HU) is used to increase HbF synthesis and improve the clinical course of sickle cell disease (SCD) patients. We studied a series of laboratory parameters concerning HbF production and reticulocyte response, and compared data between two groups: 1) 13 SCD patients treated with HU, and 2) 33 untreated SCD patients. Higher values of Hb concentration, mean cell volume (MCV), mean cell hemoglobin (MCH), mean reticulocyte volume (MRV), HbF concentration, percentage of F-cells, and amount of HbF/F-cells were observed in the treated group of patients. There was no correlation between Hb and HbF elevations. The reticulocyte count, immature reticulocyte count, mean fluorescence index (MFI), and neutrophil count were significantly lower in treated patients. Taken together, these findings suggest that a decreased hemolytic process occurred in patients undergoing HU treatment. There was a significant correlation between MCV and HbF, between MRV and HbF, and between MRV and F-cell in patients taking HU. These data indicate that macroreticulocytes correspond to F-reticulocytes, and that an increase in MRV in SCD patients using HU may be an indirect signal of F-cell production. The concentration of HbF/F-cells was higher in patients treated with HU, but this increase apparently was independent of F-cell production. Reticulocyte (RTC) parameters, as assessed by hematological analyzers, may be useful for following erythropoietic changes in patients receiving HU, and can indirectly indicate HbF and F-cell production induced by HU therapy.

Studies on the haemotoxicity of chloramphenicol succinate in the Dunkin Hartley guinea pig

In man, chloramphenicol (CAP), induces two major haemotoxic effects. First, a reversible, dose-related reticulocytopenia and anaemia developing during treatment. Second, a non-dose-related aplastic anaemia (AA), developing weeks after treatment, is often irreversible and fatal. In previous studies, we developed a mouse model of the reversible reticulocytopenia/anaemia using CAP succinate (CAPS); attempts to induce AA in the mouse with CAPS were unsuccessful; in the rat, CAPS induced only minimal haemotoxicity. We therefore wished to investigate haematological changes caused by CAPS in a third rodent, particularly in relation to the induction of significant 'late stage' bone marrow depression (AA). Female guinea pigs were gavaged with CAPS in three experiments. In a dose ranging study, CAPS (at 2500 and 3500 mg/kg) was administered daily for 9 days, and blood examined at 1 day post dosing. CAPS induced increased erythrocyte values (an apparent haemoconcentration effect), and reduced reticulocytes and femoral marrow nucleated cell counts (FNCC). In a second experiment, CAPS was given at 333, 666 and 1000 mg/kg (13 days); haematological changes were compared with results from the initial study, with evidence of dose-related effects. In a final experiment, CAPS was administered (825 mg/kg, 16 days) and blood studied at 1, 12, 28 and 63 days post dosing. At day 1, erythrocyte values were decreased (NS), and reticulocytes and FNCC were reduced; the marrow was hypocellular with erythroid depletion. At 12 and 28 days, values returned towards the normal range. At 63 days, parameters were normal. Thus, CAPS (825 mg/kg for 16 days) induced changes comparable to the reversible bone marrow depression seen in man; but there was no evidence of 'late stage' (i.e. at 63 days) marrow depression, as would be seen in a developing or overt marrow aplasia (AA). The guinea pig (like the mouse) is a model for the early events, but is not a good model for CAP-induced AA in man.

Congenital Dyserythropoetic Anemia with Sideroblasts and Ringed Forms

Letters to the EditorCongenital Dyserythropoetic Anemia with Sideroblasts and Ringed Forms Khaled Kamaleddin Mohamed and MD Abdulatif AlfaraidyFachartz Khaled Kamaleddin Mohamed Consultant Pediatrician, Department of Pediatrics, King Faisal University/King Fahd Hospital of the University, P.O. Box 40163, Al Khobar 31952, Saudi Arabia Search for more papers by this author and Abdulatif Alfaraidy Professor and Chairman, Department of Pediatrics, King Faisal University/King Fahd Hospital of the University, P.O. Box 40163, Al Khobar 31952, Saudi Arabia Search for more papers by this author Published Online:1 Sep 2002https://doi.org/10.5144/0256-4947.2002.408SectionsPDF ToolsAdd to favoritesDownload citationTrack citations ShareShare onFacebookTwitterLinked InRedditEmail AboutIntroductionTo the Editor. Congenital dyserythropoietic anemias (CDA) are a group of hereditary refractory anemias characterized by ineffective erythropoiesis, typical morphological abnormalities of erythroblasts, low or no reticulocyte response, hyperbilirubinemia and splenomegaly.1 We report a case of CDA with ringed sideroblasts presenting neonatally. This is a rare finding in CDA.2CASE REPORTA full-term male Saudi infant presented after delivery with pallor, splenomegaly (6 cm below left costal margin) and a systolic murmur over the left precordium. CBC showed hemoglobin at 11.8 g%, hematocrit 36.8%, mean corpuscular volume (MCV) 100 fl, and reticulocytes at 12.5%. Peripheral blood smear suggested erythroblastosis fetalis. Hb electrophoresis showed Hb A1 at 21.3%, Hb F 70.9%, and Hb Bart's at 7.2%. G6PD screen was normal. Echocardiography showed a small ventricular septal defect and patent ductus arteriosus. The diagnosis of a-thalassemia, probably Hb H disease, was initially considered.On the fourth day of life, the Hb dropped to 9.7 g% and the patient was transfused. Two months later, the Hb dropped to 4.2 g% and a second packed RBC transfusion was given. At age of 4½ months, Hb was 5.8 g%, MCV 77 fl, and reticulocytes 2.5%. Repeat Hb electrophoresis showed Hb A1 at 99%, and Hb A2 at 1%. Hb H preparation as well as acidified serum (Ham) test was negative. Serum ferritin was high. Bone marrow aspiration showed brisk erythropoiesis with dyserythropoietic features such as moderate megaloblastic morphology, binuclearity, cytoplasmic bridges, many mitotic granules and occasional ring sideroblasts.DISCUSSIONCDAs are a group of hereditary refractory anemias characterized by ineffective erythropoiesis, typical morphological abnormalities of erythroblasts, low or no reticulocyte response, hyperbilirubinemia and splenomegaly.3 CDA can be diagnosed in early childhood, however, diagnosis is complicated due to poor knowledge of the morphological criteria and the large number of differential diagnoses that have to be excluded.4Our patient had an early onset of anemia and splenomegaly (at birth) He had sideroblasts in the bone marrow with occasional ring forms, which is a rare finding in CDA.2 Absence of microcytosis and hypochromia makes sideroblastic anemia unlikely.5The first Hb electrophoresis revealed a picture of α-thalassemia trait. The level of Hb Bart's (7.2%) should have been considered relatively low for Hb H disease.6 The correct diagnosis of CDA was made at the age of 4½ months after presentation. However, the mean age for establishing the correct diagnosis seems to be much later in other reports.7ARTICLE REFERENCES:1. Delaunay J, Iolascon A. "The cogenital dyserythropoietic anemias" . Baillieres Best Pract Res Clin Hematol. 1999; 12:691–705. Google Scholar2. Soysal T, Akun E, Ozaras R, et al.. "Congenital dyserythropoietic anemia type 1 with ringed sideroblasts" . Hematologia (Budapest). 2000; 30:45–9. Google Scholar3. Tekinalp G, Sarici SU, Erdinc AS, et al.. "Lethal hydrops fetalis due to congenital dyserythropoietic anemia in a newborn: association of a new skeletal abnormality" . Pediatr Hematol Oncol. 2001; 18:537–42. Google Scholar4. Rossler J, Havers W. "Diagnosis and genetics of congenital dyserythropoietic anemia (CDA)" . Klin Pediatr. 2000; 212:153–9. Google Scholar5. Elias S. Sideroblasts anemias. In: Behrman , Kliegman , Jenson editors. Nelson Textbook of Pediatrics. Philadelphia: Saunders, 2000: 1471. Google Scholar6. Quadri MI, Islam SI, Zaki Nasserullah. "The effect of α-thalassemia on cord blood red cell indices and interaction with sickle cell gene" . Ann Saudi Med. 2000; 20:367–70. Google Scholar7. Iolascon A, Delaunay J, Wickramasinghe SN, et al.. "Natural history of congenital dyserythropoietic anemia type 2" . Blood. 2001; 15;1258–60. Google Scholar Previous article Next article FiguresReferencesRelatedDetails Volume 22, Issue 5-6September-November 2002 Metrics History Published online1 September 2002 InformationCopyright © 2002, Annals of Saudi MedicinePDF download

Changes in erythropoiesis assessed by reticulocyte parameters during ultralong distance running.

To investigate the possibility of early changes in erythropoiesis during prolonged exercise being reflected in reticulocyte parameters. This was a case-control field study of hematological variables in a group of ultramarathon runners competing in a 6-day track race. A 6-day ultramarathon in Colac, Australia. 7 male and 1 female experienced ultramarathon runners. A track race of 6 days' duration. A wide range of red cell and reticulocyte parameters. Resting red cell parameters were within normal clinical limits. However, except for the expected findings typical of hemodilution, red cell parameters were relatively unchanged during and after the event, with the exception of small but statistically significant changes in number and percentage of macrocytic, microcytic, hypochromic, and hyperchromic red cells. No reticulocytosis was found in an event that would have been expected to be associated with significant foot-strike hemolysis; however, an increase in the percentage of reticulocytes with high RNA content late in the event indicates early release from the marrow. Reduction in reticulocyte mean cell volume, which is consistent with functional iron deficiency, was demonstrated during the event. This finding is consistent with changes in some of the iron-related parameters associated with the acute phase response, but the dissociation in time between these changes makes a causal relationship unlikely. Other changes such as those in reticulocyte hemoglobin distribution width, reticulocyte distribution width, cell hemoglobin concentration mean, and lack of change in corpuscular hemoglobin are not typical of true iron deficiency, and the mechanism of these changes is currently unknown. The hematopoietic system demonstrates remarkable stability in the face of very significant exercise stress. No reticulocyte response was demonstrated in this study, but reticulocyte changes both consistent with and contrary to early release from the marrow were demonstrated after several days of strenuous running. The significance of several newly developed ratios of red cell and reticulocyte parameters in conditions of exercise stress requires further investigation.

An integrated pharmacodynamic analysis of erythropoietin, reticulocyte, and hemoglobin responses in acute anemia.

To determine by pharmacodynamic (PD) analysis physiologically relevant parameters of the cellular kinetics of erythropoiesis in acute anemia. The PD relationships among erythropoietin (EPO), reticulocyte, and RBC (Hb) responses were investigated in young adult sheep in acute anemia induced twice by two controlled phlebotomies separated by a 4-week recovery period. The phlebotomies resulted in rapid increases in plasma EPO, with maximal levels occurring at 3 to 8 days, followed by a reticulocyte response with a delay of 0.5 to 1.5 days. The Hb returned to prephlebotomy base line at the end of the 4-week recovery period. The EPO, reticulocyte count, and Hb responses were well described by a PK/PD model (r = 0.975) with the following cellular kinetics parameters: the lag time between EPO activation of erythroid progenitor cells and reticulocyte formation; the reticulocyte-to-RBC maturation time; the reticulocyte and Hb formation efficacy coefficients, quantifying EPO's efficacy in stimulating the formation of reticulocytes and Hb, respectively; the C50 PK/PD transduction parameter defined as the EPO level resulting in half the maximum rate of erythropoiesis. Physiologically relevant cellular kinetics parameters can be obtained by an endogenous PK/PD analysis of phlebotomy data and are useful for elucidating the pathophysiologic etiology of various anemias.

An evaluation of the concept of living at moderate altitude and training at sea level

Despite equivocal findings about the benefit of altitude training, current theory dictates that the best approach is to spend several weeks living at ≥2500 m but training near sea level. This paper summarizes six studies in which we used simulated altitude (normobaric hypoxia) to examine: (i) the assumption that moderate hypoxia compromises training intensity (two studies); and (ii) the nature of physiological adaptations to sleeping in moderate hypoxia (four studies). When submaximal exercise was >55% of sea level maximum oxygen uptake ( V ̇ o 2max), 1800 m simulated altitude significantly increased heart rate, blood lactate and perceived exertion of skiers. In addition, cyclists self-selected lower workloads during high-intensity exercise in hypoxia (2100 m) than in normoxia. Consequently, our findings partially confirm the rationale for ‘living high, training low’. In the remaining four studies, serum erythropoietin increased 80% in the early stages of hypoxic exposure, but the reticulocyte response did not significantly exceed that of control subjects. There was no significant increase in haemoglobin mass (Hb mass) and V ̇ o 2max tended to decrease. Performance in exercise tasks lasting ∼4 min showed a non-significant trend toward improvement (1.0±0.4% vs. 0.1±0.4% for a control group; P=0.13 for group×time interaction). We conclude that sleeping in moderate hypoxia (2650–3000 m) for up to 23 days may offer practical benefit to elite athletes, but that any effect is not likely due to increased Hb mass or V ̇ o 2max.

LETHAL HYDROPS FETALIS DUE TO CONGENITAL DYSERYTHROPOIETIC ANEMIA IN A NEWBORN: Association of a New Skeletal Abnormality

Congenital dyserythropoietic anemias (CDAs) area group of hereditary refractory anemias characterized by ineffective erythropoiesis, typical morphological abnormalities of erythroblasts, a low or no reticulocyte response, hyperbilirubinemia, and splenomegaly. A massive hydropic newborn born with a very severe anemia (Hb 4.8 g/dL), diffuse edema, hepatosplenomegaly, ascites, pulmonary edema and respiratory distress, and shortness and hallux varus deformity of the great toe of the right foot was diagnosed to have congenital dyserythropoietic anemia on the basis of the hematological (macrocytosis, anisopoikilocytosis, fragmented red cells and erythroblastosis in the peripheral blood, and erythroid hyperplasia with erythroblastosis and erythroblasts with double nuclei and thin chromatin bridges connecting these nuclei in the bone marrow) and serological (negative acidified serum lysis test and no agglutination with anti-i antibodies) findings. In this article the seventh case of neonatal congenital dyserythropoietic anemia presenting with a very severe(lethal) form of hydrops fetalis and a new (hallux varus) deformity of the great toe of the right foot is presented. Congenital dyserythropoietic anemia should be considered in the differential diagnosis of hydrops fetalis presenting with a very severe anemia and a skeletal abnormality of the great toe.

Treatment of Hemolytic Disease of the Newborn Caused by Anti-Kell Antibody With Recombinant Erythropoietin

Recent data suggest that antibody-mediated suppression of erythroid progenitors may contribute to the anti-Kell-induced alloimmune hemolytic disease of the newborn (HDN). A 32-week-old girl who was positive for Kell was born to a mother who was negative for Kell but known to have anti-Kell antibodies. After birth, the baby had HDN and hyperbilirubinemia develop (peak bilirubin 21 mg/dL at day 9 of life). which was treated with phototherapy. Although the hyperbilirubinemia resolved, she became progressively anemic (hematocrit 22%) with an inappropriately low reticulocyte response (1.1%) and erythropoietin (EPO) level (20 mU/mL). To avoid the need for a blood transfusion, she was treated with recombinant erythropoietin (rEPO) and oral iron supplements. One week after starting EPO, the reticulocyte count increased to 9.1%. Erythropoietin therapy was continued for a total of 9 weeks, with resolution of her anemia at the end of therapy (hematocrit 35%). Thus, we were able to successfully treat the anemia with rEPO with avoidance of blood transfusion. This patient demonstrates that the antibody-mediated erythroid suppression in Kell alloimmune anemia can be overcome by rEPO. Recombinant erythropoietin should therefore be considered in the management of infants with severe or hypoproliferative anti-Kell-associated anemia.

A reply

Thank you for the opportunity of replying to the letter from Dr Bell, who has raised some interesting issues concerning mechanism of action and possible side-effects of hyperbaric oxygen (HBO), and also the ethics of undertaking this treatment. Clinical experience leads us to feel that the mechanism of action for pulsed HBO in severe blood loss anaemia is largely related to paying back the established oxygen debt. Between treatments, lactate production occurs during anaerobic metabolism in tissues due to the diminished blood oxygen content caused by severe anaemia. Hence lactic acidosis worsens, the oxygen debt arises again at which point further HBO is administered. Without these pulsed HBO exposures, there is the potential for the acidosis to continue worsening, resulting eventually in multi-organ failure. The assertion that HBO was responsible for the slower increase in the haemoglobin level is unfounded as there is certainly evidence that HBO actually exerts a favourable stimulus on erythropoiesis following massive blood loss [1]. Furthermore, we demonstrated a good reticulocyte response. It is well known that sepsis causes potent suppression of bone marrow, and once the infection in our patient was treated the haemoglobin level increased. Dr Bell's statement ‘it must be accepted that a cerebellar infarction occurred as a possible adverse consequence of decompression’ is totally implausible. Firstly, the patient was not subject to any inert gas load as she was breathing 100% oxygen, and as such the development of decompression illness is impossible. Second, at no time was the patient or attendant subject to episodes of rapid decompression capable of producing arterial gas emboli. Thus the only plausible explanation for the infarction was that of local tissue hypoxia. Unfortunately, the limited space available for the case report did not allow a full discussion regarding the decision to embark on this treatment. HBO was commenced after all acceptable conventional modes of treatment had been exhausted and then only after discussions between the Obstetric and Intensive Care consultants locally. Advice was taken from other major hyperbaric centres within the UK and also in the USA. These included the Institute of Naval Medicine (Gosport), the National Hyperbaric Centre (Aberdeen) and the hyperbaric unit in Long Beach, California. This unit has extensive experience in the field, having published a series of 26 similar patients treated with HBO with a mortality rate of only 5% (if you exclude those patients arriving late with no cerebral function) [2]. All were in total agreement that this treatment was acceptable. The comment that the treatment is unproven is inaccurate. It may be that this treatment has been logistically unavailable in the UK until recently, but severe blood loss anaemia is one of the 13 accepted conditions for treatment with HBO by the Undersea and Hyperbaric Medical Society in the USA [3], and both the Report on Confidential Enquiries into Maternal Deaths in the UK 1991–93 and the Management of Anaesthesia for Jehovah's Witnesses (March 1999) also acknowledge its use. There are now seven hyperbaric units in the UK capable of supporting critically ill patients. All provide hyperbaric and diving support for the NHS, all are members of the British Hyperbaric Association and have accepted the recommendations of the Cox report of the Faculty of Occupational Medicine published in May 1994 under the auspices of the Royal College of Physicians [4]. We agree that transfusion of blood is a relatively safe and specific treatment for haemorrhage. However, there are certain individuals who for religious or other reasons refuse blood transfusions, as is their right. The question then arises whether we should embark upon more costly interventions because of their refusal to accept transfusion. An analogy might be withholding treatment of respiratory disease from a smoker, or management of a severe head injury in a boxer. The argument is a moral one about the individual's right to choice and to still receive good medical care. In certain states in the USA (such as Texas), the Justice of the Peace can give an immediate, legally enforced order for blood replacement. This mechanism does not exist in the UK for consenting adults. As a result, we will very occasionally see these patients, and we feel that there is enough evidence to support the use of HBO if all else fails.

Some Women Pioneers In Haematology

Some Women Pioneers In Haematology

Anaemia caused by asymptomatic Plasmodium falciparum infection in semiimmune African schoolchildren

A cohort of 250 Ghanaian schoolchildren aged 5–15 years was followed clinically and parasitologically for 4 months in 1997/98 in order to study the effect of asymptomatic Plasmodium falciparum infections on haematological indices and bone-marrow responses. Of the 250 children 65 met the predefined study criteria. Thus, 14 children were parasite-free throughout (group 1), 44 had P. falciparum in all blood samples collected but no symptoms of malaria (group 2), and 7 had 1 malaria attack during the study period (group 3). At the end of the study the mean haemoglobin (Hb) level in group 1 was 123 g/L, significantly higher than the value of 114 g/L in groups 2 and 3 ( P < 0·02, adjusted for age and splenomegaly). The low Hb in group 2 was associated with subnormal plasma iron. Low Hb was associated with elevated erythropoietin (EPO) levels, and there was a positive correlation between EPO and reticulocyte counts. However, the reticulocyte response to EPO was more pronounced in uninfected than in infected children, suggesting a partial interference with erythropoiesis in asymptomatic infections. Children with asymptomatic infections had significantly higher plasma levels of tumour necrosis factor than uninfected children (geometric means 50 ng/L and 27 ng/L, respectively, P < 0·001) and this cytokine may contribute to bone-marrow suppression and disturbed iron metabolism. We suggest that asymptomatic malaria leads to a homeostatic imbalance in which erythrocyte loss due to parasite replication is only partially compensated for by increased erythropoiesis. The consequences of the reduced Hb levels on the development and cognitive abilities of children with asymptomatic infections, and the risk of precipitation of iron deficiency, deserve further study and should be considered in malaria control programmes that aim at reducing morbidity rather than transmission.

Anaemia in acute, Plasmodium falciparum malaria in children from Orissa state, India.

The severity of anaemia associated with acute, Plasmodium falciparum malaria and the extent to which haemolysis, bone-marrow suppression, and pre-existent iron deficiency contribute to the anaemia were assessed in 102 Indian children aged 2-12 years. Blood haemoglobin (Hb), plasma unconjugated bilirubin and haptoglobin, serum iron and transferrin concentrations and transferrin saturation, red cell morphology and reticulocyte response were investigated in the patients and in 50 control children. Twenty-three patients with severe anaemia (< 70 g Hb/litre) were investigated further, by bone-marrow biopsy followed by iron staining of sections or touch smears of the biopsy material. There was evidence of haemolysis in the malaria cases: in the peripheral blood smears and the significantly higher plasma concentrations of unconjugated bilirubin, lower plasma concentrations of haptoglobin and lower blood concentrations of Hb than those seen in the controls. Haemoglobin concentration correlated directly with haptoglobin (r = 0.489; P < 0.001) and inversely with unconjugated bilirubin in malaria patients (r = -0.526; P < 0.001) but not in controls (r = -0.140 and -0.061, respectively). Parasitaemia (parasites/microliter) was not significantly correlated with Hb, haptoglobin or unconjugated bilirubin. Compared with the earlier samples, follow-up samples from the patients, collected 2 weeks after discharge from hospital and antimalarial therapy, showed significant increase in Hb, haematocrit, haptoglobin and decreases in both total and unconjugated bilirubin. There was evidence of hypercellularity and mild-moderate erythroid hyperplasia, mainly of normoblastic maturation with adequate reticulocyte response, in the bone-marrow samples from the cases of severe anaemia; dyserythropoiesis was only noticed in one case and no stainable iron was detectable in 17 of the 23 cases. These observations indicate that haemolysis is the prime cause of the anaemia seen in acute falciparum malaria, although destruction of parasitised erythrocytes is not the sole cause of the haemolytic process. Bone-marrow suppression appears to have an insignificant role but pre-existent iron deficiency aggravates the severity of the anaemia.

Erythropoietin Administration in Term Infants with Hemolytic Anemia. 792

Administration of recombinant erythropoietin (EPO) has been shown to decrease or eliminate the need for erythrocyte transfusion (Tx) in preterm infants and to decrease the need for Tx in late anemia due to Rh or ABO hemolytic disease. The objective of this study was to determine if EPO administration to infants with hemolytic anemia before one month of age will prevent severe anemia and avoid the need for Tx. A planned randomized, controlled study could not be done due to parents' preference for EPO therapy once relative risks of EPO vs transfusion had been explained. Eighteen term infants were treated with EPO between 8/96 and 11/97. The etiology of the hemolytic anemia was as follows: 10 ABO incompatibility (7/10 with positive direct Coombs), 1 hemolytic elliptocytosis, 1 G6PD deficiency, 2 alpha thal. trait, 4 unknown (1 had Hb SS). At the start of EPO therapy, ages were 1.5-3.5 wks (med 2 wks), Hb levels 9-13.5 gm/dL (med 10.1; all but 1 had Hb < 11.4), reticulocytes 0.6-2.6% (med 1.5%). Serum EPO levels in 10 of these infants ranged from 2.5-20.3 mU/mL (med 9.6 mU/mL). All infants received EPO 200 u/kg SC TIW for a duration of 2-5.5 wks (med 3 wks) with oral iron 3 mg/kg day during EPO therapy and for an additional 6 wks. The reticulocyte counts increased 2-10 fold from pre-EPO values in 1-2 wks. Hb levels remained stable or increased during EPO therapy except in 1 infant with OB hemolytic disease who developed a UTI and was transfused for worsening anemia. In most infants the Hb level remained stable or declined slightly (< 1 gm/dL) after EPO was discontinued, but EPO administration was resumed in 1 infant when the Hb level dropped from 11.4 to 10.1 gms/dL during the first week off therapy. No adverse effects were observed from EPO administration. We conclude that serum EPO levels are not increased in term infants with hemolytic anemia. EPO administration results in brisk reticulocyte response with stable or increasing Hb levels and, thus, is likely to prevent or reduce the need for Tx.

Prevention of Thrombocytopenia by Thrombopoietin in Myelosuppressed Rhesus Monkeys Accompanied by Prominent Erythropoietic Stimulation and Iron Depletion

AbstractThe effectiveness of thrombopoietin (TPO) in alleviating thrombocytopenia was evaluated in a placebo-controlled study involving rhesus monkeys exposed to 5 Gy total-body irradiation (TBI) (300-kV x-rays) to result in 3 weeks of pancytopenia. Supraoptimal treatment with human recombinant TPO (10 μg/kg/d subcutaneously, days 1 to 21 after TBI) was highly effective in preventing thrombocytopenia, with nadirs for thrombocytes, on average, far higher than 100 × 109/L, a greatly accelerated recovery to normal values, and no need for thrombocyte transfusions. TPO appeared to act selectively in that neutrophil regeneration was not influenced but red blood cell lineage recovery was prominently stimulated, with reticulocyte regeneration being initiated 10 days earlier than in placebo-treated animals. The reticulocytosis was followed by a normoblastosis that occurred earlier and was more pronounced than in placebo-treated monkeys. The effect of TPO on the red blood cell lineage was also reflected in a less profound nadir for hemoglobin (Hb) and hematocrit values than in placebo controls. However, this effect was not followed by a rapid recovery to normal values, due to development of a microcytic hypochromic anemia. Iron depletion was demonstrated by measurements of total serum iron and total iron-binding capacity (TIBC) and could be prevented by prophylactic intramuscular (IM) iron before TBI or corrected by IM iron after TPO treatment. Rechallenging with TPO in week 8 after TBI demonstrated a homogenous thrombocyte response similar in magnitude to the initial response, but a greatly diminished reticulocyte response. This demonstrated that the erythropoietic response to TPO administration depends on the hemopoietic state of the animal and may reflect multiple TPO target cells. It is postulated that the extremely rapid erythropoiesis due to TPO treatment in the initial regeneration phase following myelosuppression results in iron depletion by a mechanism similar to that seen following erythropoietin treatment in patients with end-stage renal failure. It is concluded that protracted TPO therapy to counteract thrombocytopenic states may result in iron depletion and that the iron status should be monitored before, during, and after TPO treatment.

Prevention of Thrombocytopenia by Thrombopoietin in Myelosuppressed Rhesus Monkeys Accompanied by Prominent Erythropoietic Stimulation and Iron Depletion

The effectiveness of thrombopoietin (TPO) in alleviating thrombocytopenia was evaluated in a placebo-controlled study involving rhesus monkeys exposed to 5 Gy total-body irradiation (TBI) (300-kV x-rays) to result in 3 weeks of pancytopenia. Supraoptimal treatment with human recombinant TPO (10 μg/kg/d subcutaneously, days 1 to 21 after TBI) was highly effective in preventing thrombocytopenia, with nadirs for thrombocytes, on average, far higher than 100 × 109/L, a greatly accelerated recovery to normal values, and no need for thrombocyte transfusions. TPO appeared to act selectively in that neutrophil regeneration was not influenced but red blood cell lineage recovery was prominently stimulated, with reticulocyte regeneration being initiated 10 days earlier than in placebo-treated animals. The reticulocytosis was followed by a normoblastosis that occurred earlier and was more pronounced than in placebo-treated monkeys. The effect of TPO on the red blood cell lineage was also reflected in a less profound nadir for hemoglobin (Hb) and hematocrit values than in placebo controls. However, this effect was not followed by a rapid recovery to normal values, due to development of a microcytic hypochromic anemia. Iron depletion was demonstrated by measurements of total serum iron and total iron-binding capacity (TIBC) and could be prevented by prophylactic intramuscular (IM) iron before TBI or corrected by IM iron after TPO treatment. Rechallenging with TPO in week 8 after TBI demonstrated a homogenous thrombocyte response similar in magnitude to the initial response, but a greatly diminished reticulocyte response. This demonstrated that the erythropoietic response to TPO administration depends on the hemopoietic state of the animal and may reflect multiple TPO target cells. It is postulated that the extremely rapid erythropoiesis due to TPO treatment in the initial regeneration phase following myelosuppression results in iron depletion by a mechanism similar to that seen following erythropoietin treatment in patients with end-stage renal failure. It is concluded that protracted TPO therapy to counteract thrombocytopenic states may result in iron depletion and that the iron status should be monitored before, during, and after TPO treatment.

#655 Impaired erythropoietin (Epo) response to anemia in term infants under 2 months of age; hemoglobin and reticulocyte response following Epo administration

#655 Impaired erythropoietin (Epo) response to anemia in term infants under 2 months of age; hemoglobin and reticulocyte response following Epo administration

Erythropoietin (Epo), protein and iron supplementation and the prevention of anaemia of prematurity: effects on serum immunoreactive Epo, growth and protein and iron metabolism

The effect of recombinant human (r-Hu) erythropoietin (Epo) (300 IU/Kg per week for 4 weeks) was studied in healthy preterm infants (n = 14) fed human milk with additional milk protein and high doses of iron. The controls (n = 15) were in themselves a study group and were used to follow the natural course of anaemia of prematurity on such nutrition. Serum immunoreactive Epo (SiEpo) increased significantly 24 h after r-HuEpo injections (range 36 to > 128 mU/ml) and remained at these levels throughout the treatment period. r-HuEpo in such moderate doses kept haemoglobin above 11 g/dl. Bodyweight gain, protein and iron parameters indicated adequacy of dietary protein and iron. In controls, siEpo increased during the first weeks after nutritional supplementation, with a concommitant rise in reticulocyte count. At age 3 weeks, despite low siEpo levels, reticulocyte counts indicated active erythropoiesis. Following further moderate increases in siEpo, the reticulocyte count increased to high levels (7%). The reticulocyte response suggests that erythropoiesis in preterm infants is less dependent upon Epo levels than in adults.

Flow cytometric analysis of punctate and aggregate reticulocyte responses in phlebotomized cats

SUMMARY Five cats were made anemic by one-time phlebotomy, and their reticulocyte responses were monitored daily for 20 days, using manual enumeration and a standardized feline reticulocyte protocol developed and validated in our laboratory. The reticulocyte responses of 38 clinically normal client-owned cats also were analyzed manually and cytometrically to determine clinical reference ranges. Increases in the percentage of aggregate reticulocytes over the reference range were detected in 5 of 5 phlebotomized cats, using the cytometric protocol. Only 4 of the 5 cats had an increase by results of manual enumeration. Manual aggregate counts had considerable daily variation and often fluctuated in and out of reference range, whereas cytometric aggregate counts remained consistently increased for distinct periods. Increased numbers of aggregate cells could also be detected for longer periods when evaluated by flow cytometry. Increased numbers of punctate reticulocytes were detected in 4 of 5 cats, using the cytometric protocol. None of the cats had increased numbers of punctate cells when evaluated by use of the manual technique. Aggregate reticulocytes in the 38 clinically normal cats ranged from 0.1 to 0.5%, which corresponded to 8,487 to 42,120 cells/μl. Punctate reticulocytes ranged from 2 to 17%, which corresponded to 225,400 to 1,268,584 cells/μl. Flow cytometry, using a standardized analysis protocol, was a more reliable and sensitive technique for detection and evaluation of feline reticulocytosis than was manual enumeration. The sensitivity of the flow cytometer to small amounts of intracellular nucleoprotein makes this assay especially valuable for detection of punctate reticulocytosis and low degrees of aggregate reticulocytosis in cats.

Cisplatin-associated anemia: an erythropoietin deficiency syndrome.

Cisplatin-based therapy results in a cumulative anemia that is disproportionate to the effects on other blood cells. The severity of this treatment-induced anemia and the resultant transfusion requirement in cancer patients correlate with cisplatin-induced renal tubular dysfunction. Observed/expected serum erythropoietin (EPO) ratios decline with progressive cisplatin therapy and are proportionate to the degree of renal dysfunction. Recovery from anemia and of observed/expected serum EPO ratios in patients occurs after cessation of cisplatin therapy, along with restoration of renal tubular function. Creatinine clearance, however, remains permanently depressed. Cisplatin-treated rats develop progressive renal dysfunction and anemia that persists for many weeks, without effects on white blood cell counts. The anemia is also associated with a lack of expected EPO and reticulocyte response. With EPO administration, cisplatin-treated rats exhibit a greater reticulocyte response and hematocrit increment then non-cisplatin-treated rats given EPO, indicating minimal erythroid precursor cell damage from cisplatin. These results indicate the primary etiology of cisplatin-associated anemia is a transient, but persisting EPO deficiency state resulting from cisplatin-induced renal tubular damage, which can be prevented or treated by hormone (EPO) replacement.

Erythropoietin therapy for extremely premature infants

It has been well established that erythropoietin (EPO) in the dosage range of 500 units/kilo/week and perhaps slightly lower doses will produce a brisk reticulocyte response in infants with anemia of prematurity. Controlled clinical trials to demonstrate that this therapy can result in significant reductions in transfusion in these babies face several complex issues of experimental design. 1. Should the study population be relatively bigger, healthier babies (< 1500 grams birth weight, not on ventilatory support) who have lower transfusion requirements, or smaller sicker infants (< 1250 grams birth weight and on ventilators) who have higher transfusion requirements? These infants will need adequate nutrition and liberal supplementation with iron if they are to respond adequately, but the sicker smaller infants will take longer to meet these nutritional goals. 2. Timing is important because spontaneous recovery occurs at about 35 to 36 weeks of corrected gestational age, so to be effective, therapy must start before 33 weeks of gestational age and preferably earlier than that. 3. Since the end point is transfusion, the criteria used for transfusions become a critical issue. If liberal transfusion criteria are used, the study will be doubly biased in favor of EPO efficacy. There will be an increased number of transfusion events in the control population and spontaneous recovery from the anemia of prematurity will be overly suppressed in the control population. It's likely that the current transfusion criteria are too liberal thus introducing these biases to experimental design.(ABSTRACT TRUNCATED AT 250 WORDS)