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PubMed1996

Automated reticulocyte counting for monitoring patients on chemotherapy for acute leukaemias and malignant lymphomas.

Flow cytometric reticulocyte counting including their maturation fractions was performed with a Sysmex R-3000 automated analyser during follow-up after induction and/or consolidation with combination chemotherapy in patients with acute leukaemias (AL, n = 39; 58 courses) and malignant lymphomas (ML, n = 21; 29 courses). The ML patients received granulocyte colony stimulating factor (G-CSF) in addition after chemotherapy. During the leucopenic phase only reticulocytes of low fluorescence ratio (LFR) at extremely low concentration (< 10 x 10(9)/l) were found. After a median interval of 17 days (range 8-43), the middle fluorescence fraction (MFR) began to rise, preceding high fluorescence ratio (HFR) reticulocytes by a median of 1 day in AL patients with complete or partial remission. In ML patients, MFR and HFR reticulocytes appeared more often simultaneously after a median interval of only 11 days (range 8-15) and increased faster during the first week of marrow recovery showing a pattern different from AL. Granulocytes passed the critical limit of 0.5 x 10(9)/l at a median of 5 days after appearance of MFR reticulocytes in AL but in ML on the same day as MFR and HFR (day 0). The absolute reticulocyte concentration reached the lower limit of the reference range after about 10 days in AL. Thus, finding MFR and, to a lesser extent, HFR at very low cell concentrations, may serve as sensitive early indicators of marrow recovery after chemotherapy and are much more sensitive parameters than the absolute reticulocyte concentration. The higher median values for reticulocytes (total, HFR and MFR) after G-CSF therapy suggests that G-CSF is not lineage specific and may also stimulate erythroid precursor cells.

Acute Disease↗
PubMed2003

Clinical application of reticulocyte counts in dogs and cats.

Reticulocytes are anucleate immature red blood cells that contain a network of RNA, organelles, and mitochondria, which stain with supravital dyes. Both aggregate and punctate reticulocytes are present in domestic cats, and aggregate reticulocytes are used to assess the degree of regeneration in anemic dogs and cats. Multiple factors influence the degree of regenerative response to anemia. These factors include time of reticulocyte measurement, concurrent diseases, species, and ongoing therapy. Although many automated systems for reticulocyte enumeration exist, manual counts remain the gold standard in veterinary medicine.

Animals↗
PubMed2003

Early prediction of response to intravenous iron supplementation by reticulocyte haemoglobin content and high-fluorescence reticulocyte count in haemodialysis patients.

BACKGROUND: Optimal response to recombinant human erythropoietin (rHuEpo) in haemodialysis (HD) patients requires provision of sufficient available iron. However, a balance between iron requirements and supplements remains a challenge in clinical practice. Reticulocyte parameters, i.e. reticulocyte haemoglobin content (CHr) and reticulocytes in a high-fluorescence intensity region (HFR), have been shown to be accurate predictors of iron-deficient erythropoiesis as compared with traditional markers. Therefore, the aim of this study was to appraise the diagnostic power of these two parameters in the early prediction of response to intravenous iron (IVFE) medications in HD patients receiving rHuEpo. METHODS: Sixty-five HD patients with a serum ferritin level of <500 microg/l and on rHuEpo therapy for >6 months were enrolled for IVFE supplementation (100 mg iron saccharate three times a week for 4 weeks, then 100 mg every 2 weeks for 5 months). Haemoglobin, haematocrit, serum ferritin, transferrin saturation, reticulocyte count, percentage of hypochromic red cells, CHr and HFR were measured before and following iron supplementation. Response was defined as a rise in haematocrit of >3% and/or a reduction in rHuEpo dose of >30% over the baseline values at the end of the study. RESULTS: Forty-two patients had a dramatic response to IVFE therapy with a 13.5% increase in mean haematocrit and a 38% reduction in rHuEpo dose at the end of the study (P<0.001). This paralleled a statistically significant rise in CHr and HFR (P<0.001). Univariate analyses showed that ferritin (P<0.010) and CHr (P<0.001) at baseline, changes in CHr (DeltaCHr(2W), P<0.001) and HFR (DeltaHFR(2W), P<0.010) at 2 weeks, as well as changes in CHr (DeltaCHr(4W), P<0.001) and HFR (DeltaHFR(4W), P<0.001) at 4 weeks, strongly correlated with response to IVFE supplementation. Stepwise discriminant analysis disclosed that DeltaCHr(4W) in conjunction with DeltaHFR(4W) exhibited an r(2) value of 0.531 (P<0.001) to predict response to IVFE therapy. Analyses by receiver operating characteristic curves and logistic regression further revealed that DeltaCHr(4W) at a cut-off value of >1.2 pg and DeltaHFR(4W) of >500/microl were more specific to the status of iron-deficient erythropoiesis following IVFE medications. Combined use of the two cut-off values allowed for the highest accuracy in the early prediction of the response to IVFE therapy, with a sensitivity of 96% and a specificity of 100%. CONCLUSIONS: Our study shows that changes in CHr and HFR at either 2 or 4 weeks are superior to the conventional erythrocyte and iron metabolism indices and may serve as reliable parameters to detect iron-deficient erythropoiesis in HD patients undergoing rHuEpo therapy. During aggressive IVFE treatment, early identification of non-responsiveness and subsequent discontinuation of treatment can avoid the inadvertent iron-related toxicity due to over-treatment.

Anemia, Iron-Deficiency↗
PubMed1996

In vitro stability of the reticulocyte count.

A collaborative study was undertaken to investigate the effect of storage conditions on the measured reticulocyte count in venous blood samples. It was designed to cover variation in the three main determinants, namely time, temperature and anticoagulant. The aim was to determine the time for which samples could be stored for subsequent analysis for clinical purposes.

Anticoagulants↗
PubMed1984

The effects of sample size on reticulocyte counting and stool examination. The binomial and poisson distributions in laboratory medicine.

In tests that involve counting or searching for discrete objects, clinical laboratory specimens that are too small produce insensitive and imprecise test results. We found that ten of 57 surveyed New England hospital laboratories examine less than a 50-mg stool sample for parasite eggs; they are, therefore, unlikely to detect infections characterized by low concentrations of eggs in stool. Conversely, all 57 laboratories use the traditional, appropriate sample size of at least 1,000 RBCs for reticulocyte counting. In this report, we discuss theoretical and practical considerations in small sample testing.

Blood Cell Count↗
PubMed1990

Reticulocyte counting using flow cytometry.

A flow cytometric method for the quantitation of reticulocytes was refined for routine laboratory use. Blood (2 microliters) is added to 2 ml of 0.4 microM thiazole orange in phosphate buffered saline, incubated at room temperature for 90 minutes, and analysed on a Coulter EPICS Profile flow cytometer, with gating for red cells on the basis of forward and right angled light scatter. Blood (2 microliters) is also incubated with phosphate buffered saline alone as an unstained control. The adult reference range (mean +/- 2 SD), established from 30 laboratory personnel, is 19.4-59.2 x 10(9)/l (0.2-1.6%). Comparison of this technique was made on 39 selected patient samples with visual counting of cells stained with brilliant cresyl blue. The correlation between the two methods was 0.99 with slope 0.96 and intercept 0.02. The precision of the automated technique in three subjects with reticulocyte counts of 0.12%, 1.84%, and 14.3% was 33.3%, 7.3%, and 1.4%, respectively (coefficient of variations). In three patients studied serially after intensive chemotherapy, in whom the reticulocyte count quantitated by routine visual methods approached zero (0-0.1%) for eight to 18 days, the automated counts varied between 0 and 0.5%. Flow cytometric reticulocyte counting is thus a simple and highly reliable methodology for the quantitation of normal and raised reticulocyte counts but cannot be reliably used to quantitate a subnormal level.

Benzothiazoles↗
PubMed1962

Reticulocyte count.

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Erythrocyte Count↗
PubMed1999

Interference of Hb-H disease in automated reticulocyte counting.

Hb-H disease is a form of alpha-thalassemia commonly found in south-east Asia. In this condition, numerous Hb-H bodies are found in erythrocytes using reticulocyte staining preparations. This is the first study addressing the possible interference of Hb-H inclusions in automated reticulocyte counting. In this study, seven Hb-H disease samples were tested. Results obtained by the visual method and the Technicon H*3 automated method agreed relatively well. This was in contrast to the Coulter STKS automated method which generally gave lower results. Furthermore, when the incubation time was extended to 180 min in the Coulter STKS method, two Hb-H disease samples gave results several-fold higher than those obtained using the 60 min incubation time. These discrepant results were likely to have been caused by the analyser using the wrong threshold to separate reticulocytes and mature erythrocytes. High and low interference in Hb-H disease samples was observed in the Coulter STKS automated reticulocyte method. Laboratories should be aware of this potential problem, particularly when samples are from patients of Asian origin.

Autoanalysis↗
PubMed2003

Corrected end-tidal carbon monoxide closely correlates with the corrected reticulocyte count in coombs' test-positive term neonates.

OBJECTIVE: To evaluate clinical usefulness of corrected end-tidal carbon monoxide (ETCOc) measurements in healthy, term, Coombs' test-positive neonates and correlate it to the corrected reticulocyte count (RC). METHODS: ETCOc and RC were determined (at 36 +/- 12 hours of age) in 50 Coombs' test-positive neonates and compared with the ETCOc values of 50 Coombs' test-negative neonates. RESULTS: Fifty percent of Coombs' test-positive infants had RCs <5% (within a normal range for a healthy newborn) and ETCOc = 1.8 +/- 0.34 parts per million (ppm) and likely did not exhibit hemolysis. Among infants with elevated RCs, 72% had RCs between 5% and 8% and ETCOc = 2.77 +/- 0.68 ppm, and 28% had RCs >8% and ETCOc = 4.52 +/- 0.83 ppm. There was an almost linear correlation (r = 0.86) between the RC and the ETCOc among Coombs' test-positive infants. The 50 Coombs' test-negative infants had ETCOc = 1.6 +/- 0.45 ppm. Serial ETCOc measurements were performed in 14 Coombs' test-positive infants: in all but 1 infant ETCOc values declined over time. CONCLUSIONS: There is a good correlation between ETCOc and RC in Coombs' test-positive infants. ETCOc >2.5 ppm predicts a significant elevation of RC in 90% of Coombs' test-positive infants.

Blood Group Incompatibility↗
PubMed1985

Staging of idiopathic myelofibrosis. Significance of haemoglobin value and reticulocyte count.

A retrospective analysis of 18 patients with idiopathic myelofibrosis (IMF) suggested that IMF is adequately staged by combining haemoglobin value and reticulocyte count. Four stages were recognized. All deaths occurred in late stage. The stages appeared to reflect a sequential course of the disease. The present staging system adequately identified patients at high risk. However, the rate of disease progress varied greatly. It is therefore suggested that the rate of disease progress should also be considered when an individual patient is evaluated.

Aged↗
PubMed1997

Autologous stem cell transplantation: evaluation of erythropoietic reconstitution by highly fluorescent reticulocyte counts, erythropoietin, soluble transferrin receptors, ferritin, TIBC and iron dosages.

The plasma concentrations of erythropoietin (Ep), soluble transferrin receptors (sTfRs), iron, total iron binding capacity (TIBC) and ferritin were monitored in five leukaemia patients undergoing autologous bone marrow stem cell transplantation (BMSCT) and in 10 lymphoma and 21 ovarian cancer patients undergoing autologous peripheral blood SCT (PBSCT); 9/21 ovarian cancer patients received recombinant human G-CSF and Ep and six recombinant human GM-CSF and Ep following SCT. All parameters were evaluated in relation to the kinetics of erythroid reconstitution as evaluated by haemoglobin (Hb) and reticulocyte levels [including the fraction of immature reticulocytes, also called highly fluorescent reticulocytes (HFR)]. Leukaemia patients undergoing BMSCT showed only a delayed (occurring at days 35-50 after SCT) and partial RBC, neutrophil and platelet recovery, whereas all patients undergoing PBSCT exhibited a rapid (occurring at days 10-15 after SCT) and sustained haemopoietic recovery. The various levels of erythroid rescue observed among these patients markedly influenced the kinetics of the different parameters investigated: (i) in leukaemia BMSCT patients sTfRs declined following SCT and remained at low levels thereafter, whereas Ep, iron. TIBC and ferritin showed a progressive and significant increase; (ii) in the different groups of patients undergoing PBSCT: (a) sTfR levels first declined following SCT and then returned to pre-therapy values at days 12-16, this response preceded erythropoietic recovery; (b) Ep, total iron, TIBC and ferritin showed an initial increase in the first days following SCT and then returned to pre-therapy values. Altogether, these observations indicate that: (i) both sTfR levels and reticulocyte counts are predictive parameters of erythropoietic recovery; (ii) coordinated changes of biochemical parameters underlying iron metabolism (iron, TIBC and ferritin) accompany erythroid rescue following SCT.

Adolescent↗
PubMed2001

Association of helminth infection with decreased reticulocyte counts and hemoglobin concentration in Thai falciparum malaria.

Following a study showing an association between Ascaris and protection from cerebral malaria, we conducted a cross-sectional study comparing admission hemoglobin concentrations in relation to exposure to helminth infection in 2 separate groups of patients: 111 cerebral malaria cases and 180 mild Plasmodium falciparum malaria cases. Hookworm infections were excluded. Mean hemoglobin concentrations were significantly lower in helminth-infected patients compared to those without helminths, both in the cerebral malaria group (10.1+/-3 [n = 47] versus 11.2+/-2.4 g/dl [n = 64], P = 0.04) and the mild malaria group (11+/-2.5 [n = 89] vs 12.2+/-2.7 g/dl [n = 91], P = 0.004). Median reticulocyte counts, only available in the cerebral malaria group, were lower in helminth-infected patients compared to those without helminths (15,340/23,760 per microl, P = 0.03). Adjustments for confounders such as body mass index did not alter these associations. These data are consistent with a mechanism causing anemia linked to differences in the immune response of helminth-infected patients during malaria.

Animals↗