Comparison of reticulated platelet count and mean platelet volume determination in the evaluation of bone marrow recovery after aplastic chemotherapy

Red Blood Cells and Platelets Conventional and Research Parameters: Stability Remarks Before Their Interpretation

OBJECTIVES

To analyze the stability of red blood cells, platelets, and reticulocytes of the research parameters, in combination with the respective conventional parameters, for each analyte; and to quantify the morphological changes in these analytes, to propose a correction factor for each.

METHODS

Ethylenediaminetetraacetic acid (EDTA) blood specimens from patients were reanalyzed in 2-hour intervals and then, the mean percentage (X¯t%) changes were calculated. To evaluate the stability of the analyzed material, we used different criteria according to within-run and between-batch analytical variation, as well as intraindividual biological variation. Next, the mean deviation percentage of the parameters that undergo time-dependent significant changes was calculated, to obtain a correction factor.

RESULTS

Several conventional and research parameters showed significant alterations in the stability at an early time after arrival at the laboratory.

CONCLUSION

Cell variations over time can be quantified and corrected by applying a multiplying factor to the signal obtained in the analyzer.

Reticulated platelets – clinical application and future perspectives

Reticulated platelets are immature platelets freshly released from the bone marrow into the circulation and contain vestigial amounts of ribonucleic acid. Thus, they can serve as an indicator for the activity of thrombopoiesis. Despite the current lack of a standardized reference method, two types of hematology analyzers have incorporated a fully automated measurement of reticulated platelets. The “immature platelet fraction” (IPF; Sysmex XE-/XN-series) has some clinical utility in the differential diagnosis of thrombocytopenia. This is less clear for “reticulated platelets” (retPLT; Abbott CELL-DYN Sapphire/Alinity HQ). The usefulness of these parameters in the prediction of platelet recovery after chemotherapy or stem cell transplantation and as a decision aid for platelet transfusions has not been unequivocally confirmed. Recent findings have shown an association of reticulated platelets with an adverse risk in patients with coronary artery disease and stroke as well as resistance to anti-platelet therapy. Furthermore, a role of reticulated platelets for the prediction of sepsis was indicated. However, validation in larger prospective trials is necessary to establish the clinical benefit of reticulated platelets in these conditions. This review gives an overview of the available analytical methods and summarizes the current knowledge regarding the clinical application of reticulated platelets.

Clinical significance of measuring reticulated platelets in infectious diseases

This study aimed to explore the association between the percentage of reticulated platelets (RP%) and infection, and analyze the value of combined measurement of RP% with other inflammatory indicators in diagnosing infection. A total of 190 patients with signs and symptoms suspicious of infection were included in the infection group, and 70 healthy subjects with comparable percentages of gender and age were included in the control group. Peripheral white blood cell (WBC) count, percentage of neutrophils (N%), platelet count, C-reactive protein (CRP), procalcitonin (PCT), RP%, and axillary temperature were recorded. Dynamic changes in RP% with infection were measured to analyze the association between RP% and infection. The receiver operating characteristic curve was used to evaluate the value of each inflammatory indicator in diagnosing infection and analyze the diagnostic value of the combined adoption of multiple inflammatory indicators. RP% was significantly higher in the infection group than in the noninfection and control groups. The sensitivity and specificity for diagnosing infection were, respectively, 91.78% and 93.18% when RP% and CRP were used in combination, 90.41% and 90.90% when RP% and PCT were used in combination, and 100% and 100% when RP%, CRP, and PCT were used in combination. RP% changed dynamically with the progression of infection and recovered to lower than 5.5% at 2 to 7 days before the body temperature recovered to a normal level. The diagnostic value of RP% was the highest. A combined use with CRP/PCT could improve the sensitivity and specificity in the early diagnosis of infectious diseases.

Aspirin Is Associated with Improved Survival in Severely Thrombocytopenic Cancer Patients with Acute Myocardial Infarction

BACKGROUND

Patients with hematologic malignancies are at risk for severe thrombocytopenia (sTP). The risk and benefit of aspirin are not known in thrombocytopenic cancer patients experiencing acute myocardial infarction (AMI).

MATERIALS AND METHODS

Medical records of patients with hematologic malignancies diagnosed with AMI at Memorial Sloan Kettering Cancer Center during 2005-2014 were reviewed. sTP was defined as a platelet count <50,000 cells per µL within 7 days of AMI.

RESULTS

Of 118 patients with hematologic malignancies who had AMI, 58 (49%) had sTP. Twenty-five patients (43%) with sTP received aspirin as a treatment for AMI. Compared with patients without sTP with AMI, patients with sTP with AMI were less likely to receive aspirin (83% vs. 43%; p = .0001) and thienopyridine treatment (27% vs. 3%; p = .0005). During median follow-up of 3.7 years after AMI, survival was lower in patients with sTP than in those with no sTP (23% vs. 50% at 1 year; log rank p = .003). Patients with sTP who received aspirin for AMI had improved survival compared with those who did not (92% vs. 70% at 7 days, 72% vs. 33% at 30 days, and 32% vs. 13% at 1 year; log rank p = .008). In multivariate regression models, aspirin use was associated with improved 30-day survival both in the overall patient cohort and in sTP patients. No fatal bleeding events occurred. Major bleeding was not associated with sTP or aspirin use.

CONCLUSION

Treatment of AMI with aspirin in patients with hematologic malignancies and sTP is associated with improved survival without increase in major bleeding. The Oncologist 2017;22:213-221Implications for Practice: In patients with hematologic malignancies and acute myocardial infarction with severe thrombocytopenia (platelet count < 50,000 cells/µL), guideline-recommended medical therapy is often withheld because of the fear of major bleeding. In this study, aspirin therapy was associated with improved survival without an increase in major bleeding in this high-risk patient cohort.

Thrombocytopenia and platelet transfusion in the neonate

Neonatal thrombocytopenia is widespread in preterm and term neonates admitted to neonatal intensive care units, with up to one-third of infants demonstrating platelet counts <150 × 10(9)/L. Thrombocytopenia may arise from maternal, placental or fetal/neonatal origins featuring decreased platelet production, increased consumption, or both mechanisms. Over the past years, innovations in managing neonatal thrombocytopenia were achieved from prospectively obtained clinical data on thrombocytopenia and bleeding events, animal studies on platelet life span and production rate and clinical use of fully automated measurement of reticulated platelets (immature platelet fraction). This review summarizes the pathophysiology of neonatal thrombocytopenia, current management including platelet transfusion thresholds and recent developments in megakaryopoietic agents. Furthermore, we propose a novel index score for bleeding risk in thrombocytopenic neonates to facilitate clinician's decision-making when to transfuse platelets.

Reticulated platelets as a marker of platelet recovery after allogeneic stem cell transplantation

Reticulated platelets (RP) are the youngest forms of platelets in blood and reflect the rate of bone marrow platelet production. In the present study, we used flow cytometric analysis to determine the percentage of RPs in patients undergoing allogeneic stem cell transplantation. We investigated 10 patients after transplantation from HLA identical siblings: five with acute myeloid leukemia (AML), four with chronic myeloid leukemia (CML), and one patient with myelodysplastic syndrome (MDS). Of the patients examined, four patients underwent allogeneic bone marrow transplantation and six patients underwent peripheral blood stem cell transplantation. It was observed that the initially reduced percentage of RPs (2.9 +/- 1.7%; mean +/- SD) was significantly higher (P = 0.0109) in all patients (13.6 +/- 6.4%) in the following 10-26 days. The RP percentage peak preceded the recovery of peripheral platelet count up to 45.6 x 10(9)/l on average by 3 days. We found no difference in RP% between the AML and CML patients but we did observe that in CML patients the RP percentage increased on average 7 days earlier than in AML patients. The elevated RP percentage reflects increased bone marrow regeneration and can be considered an additional marker of thrombopoietic recovery in the patients undergoing allogeneic stem cell transplantation.

Evaluation of platelet turnover by flow cytometry

The number of circulating newly produced platelets depends on the thrombopoietic capacity of bone marrow as well as platelet removal from the bloodstream. Flow cytometric analysis with thiazole orange (TO), a fluorescent dye that crosses platelet membranes and binds intracellular RNA, has been used to measure circulating reticulated platelets (RPs) with high RNA content as an index of platelet turnover. We first assessed the specificity of TO flow cytometry and then applied this method in the diagnosis of thrombocytopenia caused by impaired platelet production or increased destruction. We also explored the utility of TO flow cytometry to predict thrombocytopoiesis after chemotherapy-induced bone marrow aplasia. Venous blood, anticoagulated with K(2)EDTA, was incubated with 0.6 microg/ml TO plus an anti-GPIIIa monoclonal antibody. The mean percentage of RPs in control subjects (n = 23) was 6.13 +/- 3.09%. RPs were 10.41 +/- 9.02% in patients (n = 10) with hematological malignancies during aplasia induced by chemotherapy and a significant increase in RPs (35.45 +/- 6.11%) was seen in the recovery phase. In 10 patients with idiopathic thrombocytopenic purpura, the percentage of TO positive platelets was 67.81 +/- 18.79 (P < 0.001 vs. controls). In patients with thrombocytopenia associated with hepatic cirrhosis (n = 21; 21.04 +/- 16.21%, P < 0.001 vs. controls) or systemic lupus erythematosus (n = 6, 29.08 +/- 15.57%; P < 0.001 vs. controls) increases in TO-stained platelets were also observed. Measurement of TO positive platelets may be a reliable tool for the laboratory identification of platelet disorders, with a higher sensitivity than measurement of platelet volume. Measurement of RPs may also prove useful to recognize the underlying pathogenetic mechanisms in thrombocytopenia.

Reticulated platelet levels in patients with ulcerative colitis

BACKGROUND AND AIMS

In this study, we investigated whether reticulated platelets (RP) would be useful markers in the evaluation of ulcerative colitis (UC) activity and also aimed to gain indirect information about the platelet kinetics.

MATERIALS AND METHODS

Complete blood count, C-reactive protein, erythrocyte sedimentation rate, and proportion of RP were measured in 16 active, 21 inactive UC patients, and 20 healthy blood donors. UC activity was assessed by Truelove-Witts criteria.

RESULTS

Mean platelet count was increased in patients with active compared to inactive UC (p=0.008) or healthy donors (p=0.000). Mean platelet volume (MPV) was significantly decreased in patients with active compared to inactive (p=0.015) and healthy donors (p=0.001). RP values was significantly decreased in active and inactive UC groups compared to healthy donors (p=0.000, p=0.000, respectively), while there was no significant difference between active and inactive UC patients (p=0.980). Significant negative correlation between platelet count and MPV in patients with active UC (r=-0.542, p=0.030) was observed.

CONCLUSIONS

RP values is reduced in active and inactive UC patients compared to healthy donors. To our knowledge, this is the first study about proportion of RP with UC in literature. However, the role of low RP values have not been determined clinically. Further studies are needed to evaluate the role of platelet abnormalities and changes in megakaryopoiesis caused by inflammatory state on low MPV and RP values during the course of UC.

Reticulated platelet counts correlate with treatment response in patients with idiopathic thrombocytopenic purpura and help identify the complex causes of thrombocytopenia in patients after allogeneic hematopoietic stem cell transplantation

BACKGROUND

In thrombocytopenic conditions of unknown origin, quantification of reticulated platelets (RP) in the peripheral blood by flow cytometry has been shown to differentiate increased platelet (Plt) turnover from insufficient Plt production.

METHODS

We used a whole blood flow cytometry method combining thiazole orange and anti-CD41a-staining to assess RP in 71 healthy subjects, six with thrombocytopenic myelodysplastic syndrome (MDS), nine with liver cirrhosis, 14 patients with idiopathic thrombocytopenic purpura (ITP), and 12 patients who had undergone hematopoietic stem cell transplantation (HSCT).

RESULTS

Patients with MDS had normal, patients with liver cirrhosis had slightly elevated RP counts compared to healthy subjects. ITP patients had elevated RP counts, and RP >15% were associated with treatment response (P = 0.015). In 7/10 patients after HSCT, an increase of RP preceded Plt recovery, whereas in patients with secondary thrombocytopenia after normal regeneration, the assessment of RP allowed the differentiation between conditions with high Plt turnover, such as GvHD and microangiopathy, indicated by high RP counts, and graft failure, indicated by low RP counts.

CONCLUSIONS

Our data provide the rationale for prospective studies on the diagnostic and prognostic value of RP counts in larger patient populations with ITP and after HSCT.

Comparison of methods for determining platelet numbers and volume in Cavalier King Charles spaniels

OBJECTIVE

The purpose of this study was to compare platelet concentration in cavalier King Charles spaniels (CKCS) measured by different methods commonly used in veterinary hospitals and commercial laboratories.

METHODS

Blood samples obtained from 41 CKCS [corrected] were analysed by impedance cell counter, laser cell counter and microscopic estimation. Quantitative buffy coat analysis was performed only on 17 samples, selected from CKCS [corrected] that had low platelet counts detected by cell counters. Platelet counts, platelet estimations and platelet parameters using these different methods were compared.

RESULTS

The median platelet number was lower when estimated using impedance cell counter (1363x10(9)/I) with respect to laser cell counter (1723x10(9)/I), microscopic estimation (238x10(9)/I) [corrected] or quantitative buffy coat analyser (292x10(9)/I) [corrected] (P<0.01). Although impedance cell counter, laser cell counter and microscopic estimation were positively correlated, there was no acceptable agreement among methods. CKCS [corrected] with macrothrombocytes in blood smears had significantly lower counts on impedance cell counter, laser cell counter and microscopic estimation. The percentages of CKCS [corrected] with platelet count < 100x10(9)/I [corrected] were 34.1 per cent (impedance cell counter), 26.8 per cent (laser cell counter), 22.0 per cent (microscopic estimation) (not statistically different) and 5.8 per cent (quantitative buffy coat analyser) (P<0.05).

CLINICAL SIGNIFICANCE

CKCS [corrected] with macrothrombocytosis have low platelet counts on impedance cell counters, laser cell counters and microscopic estimation. CKCS [corrected] with low platelet counts may have a normal platelet crit detected by a quantitative buffy coat analyser and thus a normal circulating platelet mass.

Impact of aspirin therapy in cancer patients with thrombocytopenia and acute coronary syndromes

BACKGROUND

Patients with cancer who have thrombocytopenia may experience acute coronary syndromes (ACS), and the use of aspirin (ASA) poses an increased risk of bleeding. The purpose of this study was to test the hypothesis that the benefit of ASA therapy in the treatment of ACS would extend to cancer patients with thrombocytopenia and outweigh the risks of severe bleeding.

METHODS

The records of all cancer patients diagnosed with an ACS in 2001 and referred for cardiology consultation were reviewed. Patients were divided into 2 groups on the basis of platelet count, >100 cells k/microL and < or = 100 cells k/microL. Data were collected on the use of ASA therapy, bleeding complications, and survival rates. The authors assessed group differences by using the Wilcoxon rank sum test or 2-tailed Fisher exact test, as appropriate. Univariate and multivariate logistic regression models were used to assess factors potentially associated with 7-day survival.

RESULTS

In cancer patients with ACS and thrombocytopenia, those who did not receive ASA had a 7-day survival rate of 6% compared with 90% in those who did receive ASA (P < .0001). There were no severe bleeding complications. Patients with a platelet count (>100 cells k/microL) who received ASA had a 7-day survival rate of 88% compared with 45% in those who did not receive ASA (P = .0096).

CONCLUSIONS

Therapy with ASA was associated with a significantly improved 7-day survival after ACS in cancer patients, with or without thrombocytopenia, and not associated with more severe bleeding.

Measurement of reticulated platelets by simple flow cytometry: An indirect thrombocytopoietic marker

BACKGROUND

The aim of this study was to determine whether measurement of reticulated platelets (RP) by flow cytometry directly from whole blood, with no fixation or manipulation, is as useful a thrombocytopoietic marker as other more complex techniques.

METHODS

RP percentage was prospectively assessed in thrombocytopenic patients (platelets <100x10(9)/L) and non-thrombocytopenic controls using a direct, whole-blood, dual-labelling flow cytometric method. Direct, whole-blood double coverage was achieved using a monoclonal antiglycoprotein (GP)-III antibody (CD61-PerCP(R)) for platelet identification and thiazol orange (Retic-count(R)) as platelet mARN stain. After establishing thrombocytopenia etiology, patients were grouped according to whether their rate of thrombopoiesis was increased or decreased.

RESULTS

RP were measured in 53 thrombocytopenic patients with several etiologies and in 53 non-thrombocytopenic controls. The mean RP in 14 thrombocytopenic patients with no increased thrombopoietic activity was 4.8% (95% CI: 3.2-6.4) and the RP absolute number was 1.98x10(9)/L (95% CI: 1.3-2.6). The mean RP in 17 thrombocytopenic patients with increased thrombopoietic activity was 29.4% (95% CI: 24.7-34.1) and the RP absolute number was 7.24x10(9)/L (95% CI: 4.9-9.5).

CONCLUSIONS

RP measurement by flow cytometry, directly from whole blood without manipulation, is a useful screening test to differentiate thrombocytopenia with high or low thrombopoietic activity.

Reticulated platelets: a reliable measure to reduce prophylactic platelet transfusions after intensive chemotherapy

BACKGROUND

Reticulated platelets (RPs) are the youngest circulating platelets (PLTs). The aim of our study was to predict PLT recovery with RP percentage (RP%) and therefore to identify PLT transfusions that could be avoided after autologous peripheral blood progenitor cell (PBPC) transplantation.

STUDY DESIGN AND METHODS

With a whole-blood dual-labeling flow cytometric method, RP% was prospectively assessed in 47 patients who received myeloablative chemotherapy followed by autologous PBPC transplantation. Retrospective analysis of RP evolution identified three time points: nadir of the RP% (NRP), imminent PLT recovery (IPR) corresponding to an RP% of greater than 7 percent, and PLT transfusion autonomy (PTA).

RESULTS

Median occurrences of NRP, IPR, and PTA were on Days +5, +8, and +12 after transplantation, respectively. The RP% value at NRP (4%) was significantly lower compared to the IPR (15%) and PTA (14%). Thirty patients (64%) achieved PTA within 4 days after IPR. On Day +8, if RP% was greater than 7 percent, positive and negative predictive values for PTA within 4 days, specificity, and sensitivity were 79, 63, 66, and 76 percent, respectively. Fever between IPR and PTA was the only factor found to negatively influence PLT recovery (p = 0.02). All patients required at least one PLT transfusion. Among patients with rapid PLT recovery (IPR-PTA interval < 4 days; n = 30), half of them received one PLT transfusion after RP increase, which could be avoided.

CONCLUSION

These encouraging results may allow us to reduce the prophylactic PLT transfusion according to patients RP% increase.