Prognostic Implications of Immature Platelet Fraction at 5-Year Follow-up Among ACS Patients Treated With Dual Antiplatelet Therapy

Objective: Platelets are strongly associated with cardiovascular events due to their role in thrombotic processes. Reticulated platelets have higher prothrombotic potential. The aim of the study was to evaluate the effectiveness of immature platelet fraction (IPF) in predicting long-term clinical outcomes in patients with acute coronary syndrome (ACS). Methods: This prospective, observational study enrolled patients with ACS treated with dual antiplatelet therapy comprising acetylsalicylic acid and clopidogrel or ticagrelor. The primary outcome was a composite endpoint defined as major adverse cardiovascular events (MACE): all-cause death, myocardial infarction (MI), ischemic stroke, or unplanned revascularization. IPF was determined using flow cytometry in the first 24 h of hospitalization. MACE were evaluated by 2 physicians based on electronic databases and source documentation including discharge letters received from patients upon telephone contact. Results: Overall, there were 140 ACS patients (mean age 65.1 ± 11.7, 37 females [26.4%]) included in this study. Of them, 22.9% had diabetes mellitus, 69.3% hyperlipidemia, 25% had a history of MI. The median IPF values were 2.85 [1.8-4.2] %. Clinical follow-up (median time: 57 months [interquartile range 55-59 months]) was available for 130 patients (92.9%). MACE occurred in 27 patients (20.8%). There were higher rates of MACE at higher IPF tertiles (3rd vs 1st tertile: HR = 5.341 95% CI: 1.546-18.454, P = .008). Cox regression analyses showed that IPF level was independently associated with MACE. Time-dependent receiver-operating characteristic curve analysis revealed area under the curve of 0.656 for 5-year outcome with an IPF cutoff point of 3.45% being 63.0% sensitive and 65.0% specific for MACE. Conclusions: The study showed IPF may be an independent predictor of long-term mortality and MACE (ClinicalTrials.gov number, NCT06177587).

Immature platelet fraction and immature platelet count as novel biomarkers of elevated platelet reactivity in NSTE-ACS patients receiving dual antiplatelet therapy

BACKGROUND

Antiplatelet therapy is the cornerstone of treatment for patients presenting with acute coronary syndrome (ACS) treated with percutaneous coronary intervention (PCI). Some patients may not respond to such therapy adequately, which is associated with a greater risk of ischemic events. Reticulated platelets are the youngest, largest, and most active platelet subtype. They have been initially shown to be associated with an increased risk of cardiovascular (CV) events and increased platelet activity.

OBJECTIVES

The aim of the presented study was to evaluate whether the immature platelet fraction (IPF) reflects the response to antiplatelet treatment in invasively managed ACS patients.

MATERIAL AND METHODS

This prospective study enrolled ACS patients treated with PCI and dual antiplatelet therapy (DAPT) comprising acetylsalicylic acid (ASA) and clopidogrel or ticagrelor. In all patients, venous blood was collected within 24 h after the procedure. Platelet parameters were measured, including IPF using the Sysmex hematological analyzer and adenosine diphosphate (ADP)-induced platelet reactivity using the Multiplate® Analyzer.

RESULTS

A total of 108 patients were enrolled, including 62 with ST-segment elevation ACS (STE-ACS) and 46 with non-ST-segment elevation ACS (NSTE-ACS). Of them, 20.4% had diabetes mellitus, 26.9% had a history of MI and 59.2% of smoking. Spearman's correlation analysis demonstrated that higher IPF and immature platelet count (IPC) values are associated with increased ADP-induced platelet reactivity (respectively: rho = 0.387, 95% confidence interval (95% CI): 0.101-0.615, p = 0.008; and rho = 0.458, 95% CI: 0.185-0.666, p = 0.001) in NSTE-ACS but not in STE-ACS patients.

CONCLUSION

Immature platelet count and IPF may be valuable markers of platelet activity in patients with NSTE-ACS treated invasively and receiving DAPT (ClinicalTrials.gov No. NCT06177587).

Immature platelets in COVID-19

Platelets play a critical role in immune response. Coronavirus disease 2019 (COVID-19) patients with a severe course often show pathological coagulation parameters including thrombocytopenia, and at the same time the proportion of immature platelets increases. In this study, the platelet count and the immature platelet fraction (IPF) of hospitalized patients with different oxygenation requirements was investigated daily over a course of 40 days. In addition, the platelet function of COVID-19 patients was analyzed. It was found that the number of platelets in patients with the most severe course (intubation and extracorporeal membrane oxygenation (ECMO)) was significantly lower (111.5 ∙ 10⁶ /mL) than in the other groups (mild (no intubation, no ECMO): 203.5 ∙ 10⁶ /mL, p < .0001, moderate (intubation, no ECMO): 208.0 ∙ 10⁶ /mL, p < .0001). IPF tended to be elevated (10.9%). Platelet function was reduced. Differentiation by outcome revealed that the deceased patients had a highly significant lower platelet count and higher IPF (97.3 ∙ 10⁶ /mL, p < .0001, 12.2%, p = .0003).

Measurement of immature platelet fraction is useful in the differential diagnosis of MYH9 disorders

INTRODUCTION

Although the presence of large and giant platelets is important in screening for MYH9 disorders, platelet morphology evaluation is dependent on operator subjectivity. Immature platelet fraction (IPF%) is widely used in clinical practice because of its rapidity and reproducibility; however, IPF% has been rarely analyzed in MYH9 disorders. Therefore, our study aimed to clarify the usefulness of IPF% in the differential diagnosis of MYH9 disorders.

METHODS

We assessed 24 patients with MYH9 disorders, 10 with chronic immune thrombocytopenia (cITP), 14 with myelodysplastic syndromes (MDS) with thrombocytopenia (<100 × 109 /L), and 20 healthy volunteers. Platelet-related data, including IPF% and platelet morphology (diameter, surface area, and staining), were retrospectively analyzed.

RESULTS

Median IPF% in MYH9 disorders, 48.7%, was significantly higher than in all other groups (cITP: 13.4%, MDS: 9.4%, controls: 2.6%). IPF% in MYH9 disorders was significantly negatively correlated with platelet count and significantly positively correlated with the diameter and surface area of platelets, but a correlation was not found between IPF% and platelet staining. The area under the curve of IPF% for the differential diagnosis of MYH9 disorders was 0.987 (95% CI: 0.969-1.000), with a sensitivity of 95.8% and specificity of 93.2% when the cutoff value of IPF% was 24.3%.

CONCLUSION

Our study strongly suggests that IPF% is useful in the differential diagnosis between MYH9 disorders and other types of thrombocytopenia.

Stability over time of immature platelet fraction and comparison between EDTA and citrated whole blood samples

BACKGROUND

Immature platelets (IP) are the youngest circulating platelets, released from megakaryocytes, and demonstrating increased dimensions, significant RNA content, and enhanced activity. Immature platelet research focuses on a differential diagnostic help in patients with thrombocytopenia. The objectives of this study were to compare the variability of IP in citrate and EDTA samples, and to determine stability over time.

METHODS

Fifty-six patients were included for comparison between EDTA and citrate whole blood sample collection. Among the patients, 28 had thrombocytopenia (platelet count < 150G/L). Platelet measurement impedancemetry and fluorimetry were performed with Sysmex XN-9000. The immature platelet fraction (IPF) and absolute immature platelet count (A-IPC) were determined with a fluorescent method.

RESULTS

The mean value of platelet count with fluorescence was, in EDTA sample, 215 ± 171 and, in citrate sample, 153 ± 118 G/L. No significant difference was observed between IPF between EDTA and citrate (7.74 ± 6.68% vs. 8.45 ± 7.37%, p = 0.69), respectively. With the Bland-Altman analysis, the mean difference in the EDTA sample, between 1 and 24 h, was 8.06 ± 6.96% and 8.73 ± 7.12% for IPF, whereas in the citrate sample, between 1 and 6 h, it was 8.60 ± 7.29% and 7.54 ± 6.97%, for IPF. Comparing 1 h EDTA sample with 6 h citrate sample, the variance ratio was 0.974 (95% CI: 0.864-1.084) in IPF.

CONCLUSIONS

We confirmed the potential to conduct IP measurements up to 24 h in the EDTA sample and IPF measurements in the citrate sample for up to 6 h. These results may be useful for the use of IPF, which is a promising parameter whose interest in clinical practice and standardization is not yet well defined.

Reticulated Platelet Count as a Diagnostic Tool in Immune Thrombocytopenia (ITP)

OBJECTIVE

This study aimed to compare the reticulated platelet count between patients having thrombocytopenia secondary to autoimmune destruction (immune thrombocytopenia {ITP}), bone marrow failure, and healthy controls who presented to a tertiary care hospital in Karachi, Pakistan.

METHODOLOGY

A cross-sectional study was conducted from February 2021 to October 2022 in the Department of Hematology, National Institute of Blood Disease (NIBD) Hospital in Karachi, Pakistan, that involved examining three groups: 30 patients with immune thrombocytopenia, 30 patients with thrombocytopenia secondary to reduced production from bone marrow, and 30 healthy controls. The study utilized the Sysmex XN-1000 (Hyogo, Japan: Sysmex Corporation) automated hematology analyzer to perform a complete blood count (CBC) test. Additionally, peripheral blood was stained with Leishman stain and examined under a microscope to eliminate pseudo thrombocytopenia and identify any abnormal cells or dysplasia. The immature platelet fraction (IPF) was then performed on Sysmex XN 1000 after ensuring adequate quality control. Finally, the data were analyzed using DATAtab (Graz, Austria: DATAtab) and SPSS version 25 (Armonk, NY: IBM Corp.).

RESULTS

Of the ninety participants, the median age was 33 years with a range of 18-71 years. Patients with ITP had a significantly higher median IPF% (median=26.65, IQR=15-39.4) than thrombocytopenia due to bone marrow failure (median=9.25, IQR=4.55-14.30) and healthy controls (median=7, IQR=4.40-9.90), with a p-value of 0.001. The immune thrombocytopenia group demonstrated an increase in IPF% as platelet counts increased, indicating a significant moderate correlation between IPF% and platelets in these patients (r=0.438, p=0.016) and confirming that IPF% was an independent predictor for the detection of ITP.

CONCLUSION

Reticulated platelet count may be a useful diagnostic tool to differentiate between ITP and thrombocytopenia caused by bone marrow failure. Because of its non-invasive nature, IPF is a valuable tool for expediting the management of thrombocytopenia associated with increased IPF.

Immature platelet fraction in cardiovascular diagnostics and antiplatelet therapy monitoring

Immature platelet fraction (IPF), circulating platelets still containing RNA, can be easily calculated by automated flow cytometry, this makes them an accessible biomarker. Higher IPF concentrations were reported in patients with thrombocytopenia, patients who were smokers, and also those who were diabetics. Several studies have reported their diagnostic and prognostic importance in patients presenting with acute coronary syndromes, especially ST-segment elevation myocardial infarction, where increased IPF level is an independent predictor of cardiovascular death. In addition, higher IPF were reported in patients with inadequate response to either clopidogrel or prasugrel, suggesting their potential role in antiplatelet therapy monitoring. Their prognostic significance was also observed in both coronary artery disease and postcardiac surgery status, where their higher levels correlated with the risk of major adverse cardiac events. The current review aims to present the current evidence on diagnostic, prognostic and potentially therapeutic roles of IPF in cardiovascular medicine.

Comparison of platelet indices in dengue fever patients based on platelet transfusion: A prospective observational study in a tertiary care center

CONTEXT

Dengue fever is the most prevalent mosquito-borne viral disease in humans. Platelet indices (PIs) are given by the cell counters but are often not reported which is possibly due to under-recognition of the utility of these parameters.

AIMS

This study aimed to compare PIs in patients with dengue fever to assess their role in the outcome such as hospital stay and platelet transfusion requirements.

SETTINGS AND DESIGN

Prospective observational study in a tertiary care center, Thrissur, Kerala.

SUBJECTS AND METHODS

A group of 250 dengue patients was studied over a period of 18 months. The platelet parameters (platelet count, mean platelet volume [MPV], platelet distribution width [PDW], platelet large cell ratio [PLCR], plateletcrit [PCT] and immature platelet fraction [IPF]) were measured with Sysmex XN-1000 and followed up every 24 h. The clinical features, duration of hospital stay and platelet transfusion requirements details were collected.

STATISTICAL ANALYSIS USED

Independent t-test, Chi-square test, Karl Pearson correlation coefficient.

RESULTS

A total of sample size was 250. The study showed normal PDW and MPV, low platelet count and PCT, and high PLCR and IPF in dengue patients. There were significant differences in PIs (lower platelet count and PCT, higher MPV, PDW, PLCR, and IPF) in comparison between dengue patients based on platelet transfusion.

CONCLUSIONS

PIs may act as a predictive tool in the diagnosis and predicting outcomes in dengue fever. Low platelet count and PCT, high PDW, MPV, PLCR, and IPF in transfused dengue patients were found to be statistically significant. Clinicians need to be sensitized about the utility and limitations of these indices and rationalize the need for red cell and platelet transfusions in dengue.

Comparison of thrombocytopenia between patients with non-alcoholic fatty liver disease and those with hepatitis C virus-related chronic liver disease

AIM

Thrombocytopenia is widely recognized as a simple surrogate marker of liver fibrosis in non-alcoholic fatty liver disease (NAFLD). Thrombocytopenia of NAFLD has not been compared with that of hepatitis C virus-related chronic liver disease (CLD-C). Here, we examined whether there is any difference in the platelet counts between patients with NAFLD and CLD-C and investigated the underlying mechanisms.

METHODS

A total of 760 biopsy-confirmed NAFLD and 1171 CLD-C patients were enrolled. After stratification according to the liver fibrosis stage, platelet counts between NAFLD and CLD-C patients were compared. The platelet count, spleen size, serum albumin level, serum thrombopoietin level, and immature platelet fraction (IPF) value were also compared after covariate adjustment using propensity score (PS) matching.

RESULTS

The median platelet counts (×10⁴ /μL) of NAFLD and CLD-C patients were 20.2 and 18.7 (p = 2.4 × 10^-5 ) in F1; 20.0 and 14.5 (p = 2.1 × 10^-12 ) in F2; 16.9 and 12.3 (p = 8.1 × 10^-10 ) in F3; and 11.1 and 8.1 (p = 0.02) in F4, respectively. In the F3 group, NAFLD patients had a significantly higher platelet count and significantly smaller spleen volume than CLD-C patients. Although the serum thrombopoietin levels were comparable between NAFLD and CLD-C patients, the IPF value of NAFLD patients was significantly higher than that of CLD-C patients.

CONCLUSIONS

NAFLD patients had a significantly higher platelet count than CLD-C patients following stratification according to the liver fibrosis stage. The milder hypersplenism and higher platelet production in NAFLD than CLD-C may have contributed to this difference.

Early treatment of rituximab combined with eltrombopag for secondary thrombocytopenic purpura in rheumatoid arthritis: A case report

RATIONALE

Secondary immune thrombocytopenic purpura (ITP) is also known as acquired thrombocytopenic purpura, autoimmune disease is usually one of the important causes. There are few reports about treatment of refractory thrombocytopenic purpura in rheumatoid arthritis (RA). We report a case of refractory ITP in which changes in platelet-related markers with therapeutic agents are worthy of the attention of clinicians.

PATIENT CONCERNS

A 69-year-old woman admitted for ecchymosis on the neck and arms for 15 days presented to our hospital. She was diagnosed with RA 5 years ago.

DIAGNOSIS

The diagnosis met the American College of Rheumatology/European League Against Rheumatism 2010 classification criteria. The disease activity score 28 (DAS-28) was 4.6, indicating that the disease activity was moderate.

INTERVENTIONS

Treatment with first-line therapies and second-line treatment--eltrombopag (EPAG) were ineffective. Therefore, we performed rituximab combined with a low dose of EPAG.

OUTCOMES

The patient received 2 cycles of rituximab combined with EPAG, and reported no new petechiae on her buccal mucosa and limbs during follow-up.

LESSONS

This case suggests that early treatment of rituximab combined with EPAG is beneficial to patients with refractory ITP in RA. In terms of disease dynamic monitoring, immature platelet fraction (IPF) may be an auxiliary indicator for predicting efficacy, but its significance needs further study.

The relationship between immature platelet fraction and severity of acute bronchiolitis

BACKGROUND AND OBJECTIVES

Acute bronchiolitis is one of the most common reasons for hospitalization in infants. Although patients with acute bronchiolitis generally have a good prognosis, death can also occur. In this study, we evaluate the immature platelet fraction (IPF) as an indicator of the severity of acute bronchiolitis.

METHODS

In our study, 179 patients diagnosed with acute bronchiolitis were divided into three groups as mild (n: 48; 26.8%), moderate (n: 104; 58.10%) and severe (n: 27; 15.1%) bronchiolitis. There were 80 healthy children in the control group. The diagnostic capacity of IPF and hematological parameters (platelet distribution width (PDW), mean platelet volume (MPV), white blood cell count (WBC), and platelet count (PLT)) values to predict severity of acute bronchiolitis was evaluated using receiver operating characteristic (ROC) curves and their respective areas under the curves (AUCs) calculated with 95% confidence intervals.

RESULTS

The IPF value of patients with acute bronchiolitis was significantly higher than the healthy group (p < 0.001). In addition, a positive correlation was observed between clinical severity of bronchiolitis and IPF. The ROC curve analysis indicated that the IPF cut-off point for predicting severity of acute bronchiolitis was > 3.2% (Sensitivity of 84%, specificity of 97%). We found that the AUCs for IPF, MPV, PDW, WBC and PLT were statistically significant for bronchiolitis relative to the healthy control group. The parameter with the greatest AUC value was IPF.

CONCLUSION

The IPF may present for diagnosing and evaluating the clinical severity of acute bronchiolitis in children.

Comparison of the value of immature retyculocyte and immature platelet in the diagnosıs of sepsis

BACKGROUND

Sepsis is one of the causes of pre-treatment morbidity and mortality in the pediatric age group. In the present study, we investigated the place of the immature granulocyte percentage, (IG) immature reticulocyte fraction (IRF), and immature platelet fraction (IPF) in the diagnosis of sepsis.

METHODS

Complete blood count, C-reactive protein, (CRP) procalcitonin (PCT) and blood cultures were measured in 125 critical patients who were followed-up in the intensive care unit with the suspicion of sepsis and 65 healthy children between 2017 and 2019. In addition to the complete blood counts and routine parameters, IG, IRF, and IPF were examined in the patients.

RESULTS

When the critical patient group and the healthy control group were compared, it was found that the total number of leukocytes (white blood cells), neutrophil count, platelet count, CRP, PCT, IG, IRF, and IPF values were higher at statistically significant levels. When septic and non-septic patients were compared, it was found that the CRP, PCT,IGP, and IPF were higher at statistically significant levels in the septic patients.

CONCLUSIONS

It was concluded that CRP, PCT, IG, and IPF were significant in determining sepsis and that PCT was the most sensitive and specific biomarker in these parameters. We believe that these parameters may be suitable for practical use in determining sepsis because they give faster results and suggest the diagnosis of sepsis.

The role of immature platelet count and immature platelet fraction in determining the need for transfusion in patients undergoing CABG

BACKGROUND

Platelet dysfunction has been shown to play a role in postoperative bleeding, however it is not clear whether immature platelets (IP) can induce appropriate homeostasis to prevent excessive bleeding in patients undergoing coronary artery bypass grafting (CABG). The aim of this study was to evaluate the postoperative change in IP count (IPC), IP fraction (IPF) and mean platelet volume (MPV), and to examine their relationship with postoperative bleeding and blood transfusion.

METHODS

One hundred and forty-nine consecutive patients undergoing elective CABG were included in this prospective study. All CABGs were performed by the same surgical team in a standardised method, utilising the on-pump technique. IPC, MPV and IPF were measured pre-operatively, after the completion of surgery, and at the postoperative first, third and fifth days. The primary outcome measure of this study was whether the need for transfusion was associated with IP, IPF, MPV and platelet count.

RESULTS

There was a significant decrease of 7.77% in IPC on the day of the operation. Pre-operative IPC and IPF were correlated with postoperative drainage (p < 0.001), intraoperative blood transfusion (p < 0.001) and intensive care unit blood transfusion (p < 0.001). Pre-operative haemoglobin levels were significantly correlated with length of hospital stay. However, neither pre-operative IPC nor IPF were associated with length of hospital stay. Postoperative IPC was however associated with the length of hospital and intensive care unit stay (p = 0.008 and p = 0.009, respectively).

CONCLUSIONS

Pre-operative IPC and IPF were significantly correlated with postoperative drainage and blood transfusion frequency. In patients undergoing CABG, these can be seen as serious guiding parameters in the estimation of postoperative bleeding.

The immature platelet fraction, a predictive tool for early recovery from dengue-related thrombocytopenia: a prospective study

BACKGROUND

There is a paucity of predictive factors for early recovery from thrombocytopenia related to dengue. The immature platelet fraction (IPF%) is reflective of megakaryopoiesis and may correlate with recovery from dengue-related thrombocytopenia. Our objective was to assess the predictive value of IPF% on days 2 and 3 of illness for recovery from dengue-related thrombocytopenia.

METHODS

A prospective study was conducted among patients with dengue admitted to our institution (Nawaloka Hospital PLC) from December 2019 to October 2020. Dengue was diagnosed based on positive non-structural antigen 1 or IgM. IPF% data were extracted from the Sysmex-XN-1000 automated hematology analyzer. Clinical data were obtained from electronic medical records. Statistical analyses were performed using SPSS version 20.

RESULTS

We included 240 patients. An IPF% on day 2 of illness of >7.15% had a sensitivity of 80.0% and specificity of 70.4% for prediction of platelet recovery (defined as platelet count ≥60×109/L) on day 7 of illness. An IPF% of >7.25% on day 3 of illness had a sensitivity of 88.9% and specificity of 47.1% for predicting platelet recovery >60×109/L on day 8 of illness. The IPF% was significantly lower in patients with severe dengue. Platelet recovery was observed within 48 h after the peak IPF% was reached, regardless of severity.

CONCLUSION

We propose that IPF% values on days 2 and 3 of illness are a promising predictive tool for early recovery from dengue-related thrombocytopenia.

Impact of Reticulated Platelets on Platelet Reactivity in Neonates

Neonatal megakaryopoiesis and platelet turnover form a developmentally unique pattern by generating a pool of newly released reticulated platelets from the bone marrow into the circulation. Reticulated platelets are more reactive and hyperaggregable compared to mature platelets, due to their high residual mRNA content, large size, increased expression of platelet surface receptors, and degranulation. The proportion of reticulated platelets in neonates is higher compared to that in adults. Due to the emergence of an uninhibited platelet subpopulation, the newly formed reticulated platelet pool is inherently hyporesponsive to antiplatelets. An elevated population of reticulated platelets is often associated with increased platelet reactivity and is inversely related to high on-treatment platelet reactivity, which can contribute to ischemia. Measurements of the reticulated platelet subpopulation could be a useful indicator of increased tendency for platelet aggregation. Future research is anticipated to define the distinct functional properties of newly formed reticulated or immature platelets in neonates, as well as determine the impact of enhanced platelet turnover and high residual platelet reactivity on the response to antiplatelet agents.

Immature platelet levels correlate with disease activity and predict treatment response of thrombocytopenia in lupus patients

OBJECTIVE

The immature platelet fraction (IPF) represents recently produced platelets in bone marrow and this parameter is increased in patient with primary immune thrombocytopenia (ITP). We investigated the associations between IPF and absolute immature platelet count (AIPC), and clinical parameters in systemic lupus erythematosus (SLE), which has more complex pathological mechanisms than in primary ITP.

METHODS

Patients with SLE were retrospectively reviewed at the University of Tokyo Hospital from May, 2012 to January, 2021. The correlations between clinical parameters and the number of immature platelets were assessed with Spearman's rank correlation coefficients. A multiple logistic regression model was used to identify the independent clinical parameters for IPF and AIPC. The difference in the distribution of time for a complete response (CR) after prednisolone (PSL) administration was also evaluated by log-rank test.

RESULTS

A total of 282 SLE patients were enrolled, and 12.41% of those patients showed thrombocytopenia. IPF correlated with clinical parameters such as platelet count (r = -0.58), AIPC (r = 0.64) and systemic lupus erythematosus disease activity index 2000 (SLEDAI-2K) (r = 0.24). SLEDAI-2K [odds ratio (OR) (per unit increase), 1.07; 95% CI, 1.013 - 1.13] and thrombocytopenia (OR, 32.23; 95% CI, 11.072 - 93.80) were independent clinical parameters to account for IPF increase. IPF correlated with the number of bone marrow megakaryocytes (n = 19, r = 0.57). Notably, the probability of CR in response to PSL in AIPC-high patients was higher than in AIPC-low patients (hazard ratio, 4.62; 95% CI, 1.07 - 20.02).

CONCLUSION

IPF correlated with disease activity of SLE and represented platelet production in the bone marrow, whereas AIPC predicted a rapid response to steroids in thrombocytopenic patients with SLE.

Development of gates to measure the immature platelet fraction in C57BL/6J mice using the Sysmex XN-V series multispecies hematology analyzer

The immature platelet fraction (IPF) is a measure of newly released platelets, which has been used as a marker of platelet production in multiple human studies but is not widely available in multispecies analyzers. We developed gates to measure the IPF in diluted and undiluted murine blood samples on the Sysmex XN-1000V multispecies hematology analyzer. IPF gates were created using undiluted and diluted (1/10) blood samples obtained from adult and newborn (postnatal day 10, P10) C57BL/6J wild-type (WT) mice, and from 3 murine models of thrombocytopenia: c-MPL^-/- mice, which lack the thrombopoietin receptor (hyporegenerative); antibody-mediated thrombocytopenia; and acute inflammation-induced thrombocytopenia. P10 mice were chosen because, at their size, we could consistently obtain (by terminal phlebotomy) the blood volume needed to run an undiluted sample. The undiluted blood IPF gate successfully differentiated between mechanisms of thrombocytopenia in both adult and P10 mice. For diluted samples, 2 IPF gates were generated: a thrombocytopenic (T) gate, which performed well in samples with platelet counts (PCs) <800 × 10⁹/L in adult mice and <500 × 10⁹/L in newborn mice, and a non-thrombocytopenic (NT) gate, which performed well in samples with PCs above these thresholds. PCs and IPFs measured in diluted blood using these gates agreed well with those measured in undiluted blood and had good reproducibility. These diluted gates allow for the accurate measurement of PCs and IPFs in small (10 µL) blood volumes, which can be obtained easily from adult and newborn mice as small as P1 to assess platelet production serially.

Reticulated Platelets-Which Functions Have Been Established by In Vivo and In Vitro Data?

Reticulated platelets (RP) are the youngest platelet fraction released into the circulation. These immature platelets have increased RNA content, a larger cell volume, more dense granules, higher levels of surface activation markers and are thought to be more reactive compared to their mature counterparts. RP have been associated with cardiovascular disease, diabetes and increased mortality. Yet only a few animal studies investigating RP have been conducted so far and further investigations are warranted. Established methods to count RP are flow cytometry (staining with thiazole orange or SYTO13) or fully automated hematology analyzers (immature platelet fraction, IPF). IPF has been established as a diagnostic parameter in thrombocytopenia, cardiovascular disease and, in particular, the response to antiplatelet therapy. This review seeks to provide an overview of the key features of RP as well as preanalytical and analytical aspects that need to be considered when working with this platelet population.

Can immature platelet fraction be an early predictor for congenital pneumonia?

Aim:

Timely diagnosis and treatment of congenital pneumonia are crucial. A new hematologic parameter, immature platelet fraction, has been used to gather clinical information on the prognosis of thrombocytopenia, as well as to measure inflammatory activity in adult patients. This study aimed to compare immature platelet fraction and sepsis biomarkers in late-preterm infants diagnosed as having congenital pneumonia and to evaluate its predictive value for congenital pneumonia.

Material and Methods:

Late-preterms were categorized based on infectious vs. non-infectious etiology of respiratory distress. Two sets of blood samples for markers were taken at 12–24 (sample-1) and 48–72 hours (sample-2) after birth. Immature platelet fraction was measured using a Sysmex XN-3000 analyzer.

Results:

From a total of 30 non-thrombocytopenic late-preterms, 16 were included in the congenital pneumonia group and 14 comprised the transient tachypnea group. The groups were comparable in terms of gestational age, birth weight, and cesarean section rate. The proportion of prolonged membrane rupture was significantly higher in the congenital pneumonia group. Values of immature platelet fraction-1, immature platelet fraction-2, and procalcitonin-2 were significantly higher in the congenital pneumonia group than in the transient tachypnea group. No significant differences were found between the groups in other biomarkers. It was determined that an immature platelet fraction-1 cut-off value of 2.9% could predict congenital pneumonia with a sensitivity of 65%, a specificity of 71.4%, a positive predictive value of 70.5%, and negative predictive value of 63.7% (area under the curve=0.724; p=0.028).

Conclusion:

Immature platelet fraction may have an early predictive role in the diagnosis of congenital pneumonia.

Immature Platelet Dynamics in Immune-Mediated Thrombocytopenic States

A major challenge encountered by clinicians is differentiating presentations characterized by significant thrombocytopenia due to overlapping clinical symptoms and signs in the setting of ambiguous laboratory results. Immature platelets represent the youngest platelets that can be measured in peripheral blood by current hematology analyzers. These young platelets are larger, with higher RNA content recently released from the bone marrow. Thrombocytopenic presentations caused directly or indirectly by immune responses can lead to compensatory bone marrow responses seeking to normalize the platelet count; thus obtaining absolute immature platelet counts may be informative while triaging patients. Over the last decade, their use has expanded beyond being an early biomarker of bone marrow reconstitution post-hematopoietic stem cell transplantation to being used to establish bone marrow responses to infection and thrombocytopenias due to immune etiologies. Its accessibility as part of more detailed platelet indices obtained with routine laboratories makes it a promising option to understand the bone marrow's real-time response to disease states characterized by thrombocytopenia. This review will look at the immature platelet count as a biomarker, while presenting current attempts trying to understand how it could be used in thrombocytopenias occurring secondary to a given immune etiology.

Measurements of immature platelet fraction and inflammatory markers in atrial fibrillation patients - Does persistency or ablation affect results?

PURPOSE

Atrial fibrillation (AF) is associated with platelet hyperactivity and a higher proportion of immature platelets. We aimed to examine whether immature platelet fraction (IPF) and inflammatory markers differ between AF types and whether they are affected by ablation.

METHODS

A prospective study included patients with atrial fibrillation/flutter (AFL). We excluded patients with hematologic, inflammatory, or acute coronary states. Blood samples for IPF, white blood cells (WBC), neutrophil-to-lymphocyte ratio (NLR), and C-reactive protein (CRP) were collected at baseline, within one-hour postablation in those undergoing ablations, and the day after ablation. IPF was measured by an autoanalyzer (Sysmex 2100 XE).

RESULTS

One hundred and four patients were included (paroxysmal AF-63, persistent AF-36, AF and AFL-7, AFL alone-5), (Mean age 67.7 ± 12.8 years, 54.8% male, CHA₂ D₂ -VASC₂ 3.2 ± 1.8). Seventy-two patients underwent ablation (cryoballoon AF ablation-60, AFL radiofrequency ablation-5, both-7). There was no difference between paroxysmal and persistent AF regarding baseline markers. There was a significant change in the following parameters after ablation: WBC (baseline 6.9 ± 2.0, 1-h post 8.0 ± 2.4, and 1-day post 9.0 ± 2.8 ×10⁹ /L), NLR (2.9 ± 2.2, 3.0 ± 2.4, 4.2 ± 2.9, respectively), and CRP (3.6 ± 3.7, 3.6 ± 3.5, 12.4 ± 9.0 mg/L, respectively) (P < .05 for all). However, there were no differences in immature platelet count (8.6 ± 4.8, 8.5 ± 4.9, 8.4 ± 5.2 ×10⁹ /L) or IPF (4.6 ± 3.2, 4.7 ± 3.3, 4.9 ± 3.6%) from baseline to postablation (p = NS).

CONCLUSIONS

AF persistency does not affect IPF and inflammation. In patients undergoing cryoablation of AF, there is a postablation inflammatory process; however, platelet activation is probably not affected.

[Usefulness of immature platelet fraction measurement for diagnosis and monitoring of iron deficiency associated thrombocytopenia: about two cases]

Iron deficiency anemia is frequently associated with thrombocytosis. However, in some rare cases of very severe iron deficiency, a thrombocytopenia may occur. This condition may lead to a misdiagnosis of immune thrombocytopenic purpura and thus to unnecessary tests in this context. Here we report two patients who presented with iron deficiency associated thrombocytopenia rapidly corrected after martial supplementation. We then discuss the value of measuring immature platelet fraction (IPF), which represents the population of newly formed platelets containing a greater amount of residual RNA. For both cases, low IPF values at admission indicated a central origin of thrombocytopenia with decreased platelet production, which is the pathophysiological mechanism of iron deficiency associated thrombocytopenia.

Evaluation of Immature Platelet Fraction in Lower Respiratory Tract Infections: A Retrospective Study

Introduction

Immature platelet fraction (IPF) is a parameter of an automated hematologic analyzer and is related to platelet size and cytoplasmic RNA content. It reflects thrombopoiesis and is often used as the marker of platelet activity. IPF has been evaluated mostly in hematologic disorders and has also been evaluated in patients with gestational hypertension, sepsis, autoimmune diseases and in hospitalised patients with neutrophilia. Platelets, asides from the maintenance of hemostasis, release inflammatory mediators that can modify leukocyte and endothelial responses to various inflammatory stimuli. Lower respiratory tract infections are the leading cause of death from infections worldwide. The role of platelets in lower respiratory tract infections has been reported in many studies. IPF, which is related to platelet activation, has not been evaluated in patients with lower respiratory tract infections.

Methods

The study involved patients who fulfilled the criteria of community-acquired pneumonia (CAP) and aspiration pneumonia (AP). In addition, age and sex-matched healthy controls were involved. Whole blood samples were collected from healthy controls and from the patients on admission. The mean IPF% and C-reactive protein (CRP) levels were measured in patients with CAP, in patients with AP and in healthy controls. The mean IPF% values in patients with infection were compared to mean IPF% values in healthy controls. The mean IPF% values were compared to mean CRP levels in patients with infection. Additionally, the mean IPF% values in patients that died in the first 14 days were compared to the mean IPF% values in patients that were alive. The statistical analysis of data was performed with the Statistical Package for the Social Sciences (SPSS) for Windows, Version 13.0 (SPSS Inc, Chicago, IL). 

Results

The study population consisted of 45 patients (27 patients with CAP and 18 patients with AP), 27 males and 18 females, with a mean age of 72.11 ± 16.4 years and 39 healthy controls, 22 males and 17 females with a mean age of 64.2 ± 14.8 years. The mean CRP levels in patients with infection were 155.2±119.1 mg/dl. The mean IPF% value of patients with infection was 2.76 ± 2.27 and the mean IPF% value of controls was 1.72 ± 0.77 (p < 0.006). The IPF% value in patients with CAP was 2.55 ± 2.02 and in patients with AP 3.07 ± 2.64 (p = 0.595). The mean IPF% value in patients with infection had no linear correlation with CRP value in these patients (r = 0.076, p = 0.62). The mean IPF% value in all patients that died in the first 14 days was 3.75 ± 2.44 and the mean IPF% value in all patients alive was 2.35 ± 2.11 (p = 0.06). The mean IPF% value in patients with CAP who died in the first 14 days of hospitalisation was 5.54 ± 3.17 and in patients with CAP who were alive was 1.87 ± 0.72 (p = 0.06). The mean IPF% value in patients with AP who died was 2.63 ± 0.85 and in patients with AP who were alive was 3.41 ± 3.51 (p = 0.554).

Conclusions

Mean IPF% value is greater in patients with lower respiratory tract infections, including CAP and AP, compared to healthy controls. There is no linear correlation between IPF values and CRP values in patients with lower respiratory tract infections. In addition, there is a difference in mean IPF% value between patients who died in the first 14 days of hospitalisation compared to those who were alive, but not statistically significant.

Impact of diabetes mellitus on immature platelet fraction and its association with coronary artery disease

BACKGROUND

Higher prothrombotic status and alterations in platelet function and thrombopoiesis are associated with diabetes mellitus (DM). We assessed the impact of diabetes and glucose control on the immature platelet fraction (IPF) and their relationship with prevalence and extent of coronary artery disease (CAD).

METHODS

Consecutive patients undergoing coronary angiography were included. Significant CAD was defined as at least one vessel stenosis greater than 50%. IPF levels were measured at admission by routine blood cells count (A Sysmex XE-2100).

RESULTS

We included 1781 patients, of whom 660 (37.1%) suffered from diabetes. Diabetes was associated with advanced age and a higher cardiovascular risk profile. No difference in the mean values of IPF were observed between patients with or without DM (3.6 ± 2.5 vs 3.5 ± 2.5, P = 0.39) and neither in the rate of patients with IPF above the median (2.9%) (51.6% vs 50.6%, P = 0.73). In patients with DM, the IPF levels did not relate with glucose control parameters (glycaemia: r = -0.024, P = 0.54, glycosylated haemoglobin: r = 0.11, P = 0.72). The prevalence of CAD was significantly lower in patients with DM and IPF greater than the median (80.5% vs 86.5%, P = 0.04, adjusted odds ratio [OR] [95% confidence interval {CI}] = 0.57[0.36-0.91], P = 0.02), while not left main/three-vessel CAD (36.9% vs 38.2%, P = 0.75, adjusted OR [95%CI] = 0.91[0.64-1.28], P = 0.90).

CONCLUSION

In the present study, neither DM nor glucose control are independent predictors of IPF above the median. In patients with DM, higher IPF levels were associated with a lower prevalence of CAD and with a similar extent of severe CAD and angiographic findings. Therefore, until new data become available, elevated IPF should not be systematically applied on a large scale as cardiovascular risk marker in patients with diabetes.

Influence of diagnosis of venous thromboembolism on immature platelets, absolute platelet count and platelet aggregation over time

The extent of the involvement of platelets in venous thromboembolisms (VTE) is still not fully understood. Immature platelets are large, RNA-rich, prothrombotic platelets. They are involved in arterial thromboembolisms and are associated with adverse cardiovascular events. Their role in VTE has not been investigated before. The aim of this study was to assess different platelet parameters including immature platelet fraction (IPF), immature platelet count (IPC), absolute platelet count and platelet aggregation (PA) over time in patients with VTE at time of diagnosis, as well as at 3-10 days and at 90-110 days after diagnosis. 50 healthy volunteers similar in age and sex to patients served as controls at diagnosis. IPF was measured by the Sysmex XE-5000 analyzer, PA was assessed using the Multiplate analyzer. Diagnosis of VTE had no relevant effect on IPF and IPC whereas absolute platelet count and PA were significantly decreased compared to controls. In the course of VTE, IPF decreased significantly, whereas IPC, absolute platelet count and PA increased. In conclusion, VTE was associated with relevant changes of the absolute platelet count and PA at diagnosis, as well as changes in IPF and IPC over time reflecting a relevant and measurable platelet consumption in VTEs.

Multicenter evaluation of analytical performances of platelet counts and platelet parameters: Carryover, precision, and stability

INTRODUCTION

The correctness of the results of automated platelet analysis is still highly debated. The aim of this multicenter study, conducted according to international guidelines, was to verify the analytical performance of nine different types of hematology analyzers (HAs) in the automated platelet analysis.

METHODS

Four hundred eighty-six peripheral blood samples (PB), collected in K₃ EDTA tubes, were analyzed by ABX Pentra, ADVIA2120i, BC-6800, BC-6800 Plus, Cell-DYN Sapphire, DxH800, XE-2100, XE-5000, XN-20 with PLT-F App. Within-run imprecision and between-run imprecision were carried out using PB and material control, respectively. The carryover, low limit of quantification (LoQ), and the PB stability were evaluated.

RESULTS

The carryover was absent for all HAs. The LoQ of PLT ranged between 2.0 (Cell-Dyn Sapphire) and 25.0 × 10⁹ /L (ADVIA 2120i), while immature platelet fraction (IPF) ranged between 1.0 (XN-20) and 12.0 × 10⁹ /L (XE-5000). The imprecision (%CV) increases as the platelet count decreases. No HAs showed desirable CV_APS for PLT counts less than 50.0 × 10⁹ /L, with the exception of Cell-DYN Sapphire (CV 3.0% with PLT-O mean value of 26.7 × 10⁹ /L), XN-20 (CV 2.4% with PLT-F mean value of 21.5 × 10⁹ /L), and BC-6800 Plus (CV 1.9% with PLT-O mean value of 26.5 × 10⁹ /L). The sample stability ranged between under two hours for MPV by ADVIA2120i and 8 hours for other PLT parameters and HAs.

CONCLUSION

The findings of this study may provide useful information regarding carryover, precision, and stability of platelet counts and parameters, especially in thrombocytopenic samples. Moreover, the stability of sample for platelet analysis is conditioned by the HA and by temperature and storage time.

Immature platelet fraction: A useful marker for identifying the cause of thrombocytopenia and predicting platelet recovery

INTRODUCTION

The assessment of bone marrow thrombopoietic activity in patients with thrombocytopenia is necessary to achieve an accurate diagnosis and administer effective treatment. We evaluated the discriminatory power of the immature platelet fraction (IPF) in differentiating hyperdestructive/consumptive thrombocytopenia from hypoproductive thrombocytopenia and its potential use as a predictive marker for platelet recovery.

METHODS

In this observational study, platelet indices, including IPF, were measured in 105 healthy individuals, 27 patients with hyperdestructive/consumptive thrombocytopenia (all with immune thrombocytopenic purpura [ITP]), and 35 patients with hypoproductive thrombocytopenia (5 with aplastic anemia and 30 with cancer who were undergoing chemotherapy) using a Sysmex XN-3000 hematology analyzer.

RESULTS

The platelet distribution width, mean platelet volume, platelet large cell ratio, IPF, and absolute immature platelet count (AIPC) were significantly higher in the hyperdestructive/consumptive thrombocytopenia group than in the hypoproductive thrombocytopenia group (P < .001). The IPF showed the highest difference between the two patient groups (200%). Receiver operating characteristics analysis that showed the IPF had the largest area under the curve among all the platelet indices analyzed; its cut-off value was 2.3%. The IPF decreased 3 to 4 days in advance of platelet count elevation in patients with ITP, whereas the delta AIPC increased 3 days in advance. Furthermore, the IPF and delta AIPC increased 5.5 days and 8.5 days, respectively, before platelet counts increased up to 130.0 × 10/L in cancer patients receiving chemotherapy.

CONCLUSION

These data demonstrated that the IPF and delta AIPC are both excellent indicators of the etiology of thrombocytopenia and predictive markers for platelet recovery.

Impact of active smoking on the immature platelet fraction and its relationship with the extent of coronary artery disease

INTRODUCTION

Smoking represents a major cardiovascular risk factor, due to the induction of oxidative stress and low-grade, continuous, inflammation that contribute to promote atherothrombosis. However, the mechanisms leading to increased platelet aggregability associated with smoking are only partially defined. A potential role has been hypothesized for immature platelets, a younger and potentially more reactive fraction, previously associated with the main determinants of coronary artery disease (CAD). Therefore, the aim of our study was to define the impact of smoking on the immature platelet fraction (IPF) and its relationship with prevalence and extent of coronary artery disease.

METHODS

We enrolled a cohort of consecutive patients undergoing coronary angiography in a single centre. Significant CAD was defined as at least 1 vessel stenosis >50%, while severe CAD was defined as left main and/or three-vessel disease. IPF was measured at admission by routine blood cell count (Sysmex XE-2100).

RESULTS

We included in our study 2553 patients who were divided according to smoking status (active smokers: 512; nonactive smokers: 2041). Smokers were younger, more frequent males, with lower rate of diabetes mellitus, previous PCI and previous CABG (P < .001, respectively) and were in treatment less often with ARB, BB, nitrates, statins, ASA, clopidogrel, CCB and diuretics (P < .001, respectively) as compared to nonactive smokers. Higher percentage of smokers was observed in patients with higher IPF values, and at multivariate analysis, active smoking resulted as an independent predictor of higher IPF (adjusted OR [95% CI] = 1.59[1.03-2.45], P = .035). Among smokers, higher IPF was associated with lower ejection fraction (P = .034), percentage of acute coronary syndrome (P = .002) and platelet count (P < .001) compared to ones with lower IPF. However, the IPF (according to quartiles values) was not associated with the prevalence and extent of CAD (82.5%, 80.4%, 86.1% and 80.9%, from 1st to 4th quartile, respectively, adjusted OR[95% CI] = 0.98[0.79-1.23], P = .89) and severe CAD (31%, 31.1%, 39.1% and 35.2%, from 1st to 4th quartile, respectively, adjusted OR[95% CI] = 1.03[0.86-1.23], P = .76).

CONCLUSION

The present study shows an independent association between active smoking and the levels of immature platelet fraction in patients undergoing coronary angiography. However, among active smokers, IPF did not result as an independent predictor of CAD or severe CAD.

Reference interval for immature platelet fraction on Sysmex XN haematology analyser in adult population

Introduction

The Sysmex XN-series haematology analyser has newly adopted a fluorescent channel to measure immature platelet fraction (IPF). To promote the clinical utility of this promising parameter, establishing a reliable reference interval is mandatory. According to previous studies, IPF values may be affected by the employed analyser and the ethnic background of the individual, but no differences seem to be found between individuals’ genders. Therefore, this study aimed to define the reference interval for IPF in a Spanish population following Clinical and Laboratory Standard Institute (CLSI) guidelines.

Materials and methods

A total of 153 healthy Caucasian adults from Spain met the inclusion criteria. IPF measurement was performed by means of a Sysmex XN-2000 haematology analyser. A non-parametric percentile method was used to calculate the reference intervals in accordance with CLSI guidelines.

Results

The obtained reference interval for IPF on the Sysmex XN-2000 was 1.6–9.6% (90% confidence intervals (CIs) were 1.5–1.8 and 9.3–11.5, respectively). No significant gender difference in IPF reference intervals was observed (P = 0.101).

Conclusions

This study provides, for the first time, a reference interval for IPF using a Sysmex XN-2000 in a Spanish population, ranging from 1.6 to 9.6%. These data are needed to evaluate platelet production in several conditions such as thrombocytopenia, inflammatory states and cardiovascular diseases, as well as for future research.

Immature platelets and antiplatelet therapy response to aspirin in Kawasaki disease

Introduction

Kawasaki disease is a kind of systemic vasculitis that mainly damages moderate and small-sized blood vessels, and is a leading cause of coronary artery lesions (CAL). Antiplatelet therapy is a routine component of Kawasaki disease treatment strategies. So it is important to evaluate the antiplatelet effect of aspirin because of the individual biological variability of antiplatelet effect of aspirin. The immature platelet fraction (IPF) has attracted particular attention as it may influence the antiplatelet effect of aspirin. This study investigated the prognostic factors for evaluating the degree of vasculitis and the effect of antiplatelet therapy in children with Kawasaki disease.

Materials and methods

Blood samples were collected from 44 patients with Kawasaki disease before aspirin treatment and 7 to 10 days after treatment. The IPF counts, percentage of the IPF, and highly fluorescent IPF were detected by a Sysmex XE-5000 instrument. The levels of 11-dehydrothromboxane B₂ (11-DH-TXB₂), soluble CD40 ligand (sCD40L), and soluble P-selectin (sP-selectin) were measured by ELISA. The correlation between the measured factors and the degree of coronary artery damage in Kawasaki disease was analyzed.

Results

We found that 11-DH-TXB₂, sP-selectin, and sCD40L levels were much more elevated in the CAL group than in the non-coronary artery lesions (NCAL) group before aspirin treatment. The concentrations of 11-DH-TXB₂, sCD40L, sP-selectin, and IPF were reduced after aspirin treatment in the NCAL group but not the CAL group. This is related to the degree of coronary artery damage in Kawasaki disease patients. Additionally, 11-DH-TXB₂, sCD40L, sP-selectin, and IPF were positively correlated with the degree of coronary artery damage in Kawasaki disease patients.

Conclusion

The current study suggests that the presence of high plasma concentrations of 11-DH-TXB₂, sCD40L, sP-selectin, and IPF can be considered a risk factor and experimental biomarker for CAL in Kawasaki disease patients.

MYH9-macrothrombocytopenia caused by a novel variant (E1421K) initially presenting as apparent neonatal alloimmune thrombocytopenia

MYH9-related disease is a rare cause of thrombocytopenia. We report an infant girl who presented with severe thrombocytopenia at birth and was initially diagnosed with and treated for neonatal alloimmune thrombocytopenia. However, persistent thrombocytopenia led to the suspicion of congenital thrombocytopenia and subsequent identification of a novel variant in MYH9 (E1421K). In silico analysis strongly predicts that this is a disruptive substitution. Immunofluorescent analysis of neutrophils demonstrates abnormal aggregates of MYH9 protein. This case also suggests that a very high immature platelet fraction (≥40%) may be useful for rapidly differentiating MYH9-related disease from other causes of neonatal thrombocytopenia.

Mean Platelet Volume and Immature Platelet Fraction in Autoimmune Disorders

Mean platelet volume (MPV), measured using automated blood analysers, has been appraised as a potential biomarker in cardiovascular disease, diabetes mellitus, and cancer. The test, a useful tool in differentiation of thrombocytopenic states, has now been carried out for autoimmune disorders, but data are yet scarce. Controversial results have been obtained in systemic and organ-specific autoimmune disorders. Another test, the immature platelet fraction (IPF) reflects the amount of young, reticulated platelets. IPF is calculated by automated hematology analysis or flow cytometry, and it is usually high in patients with rapid platelet destruction. For both MPV and IPF, standardization of cutoff is a major need. In this review, we focus the current applicability of MPV and IPF as biomarkers in patients with autoimmune diseases.

Thrombopoietic status of patients on haemodialysis

Thrombocytopenia is a potential dialysis-related treatment complication. Developments in bio-compatible dialyser membranes have decreased the occurrence of thrombocytopenia. We investigated whether thrombopoiesis is impaired in haemodialysis patients by measuring the thrombopoietin level and absolute immature platelet number (AIPN) in the blood of patients undergoing haemodialysis. Samples were collected from the dialysis tubing pre- and post- haemodialysis in a cohort of 45 well-characterized haemodialysis patients. Thrombopoietin levels and AIPN increased following haemodialysis, despite no change in platelet count. Observed increase in release of immature platelets from the bone marrow following haemodialysis indicates possible complement activation secondary to interaction between blood constituents and the dialysis membrane.

Assessment of Immature Platelet Fraction in the Diagnosis of Wiskott-Aldrich Syndrome

Children with Wiskott-Aldrich syndrome (WAS) are often first diagnosed with immune thrombocytopenia (ITP), potentially leading to both inappropriate treatment and the delay of life-saving definitive therapy. WAS is traditionally differentiated from ITP based on the small size of WAS platelets. In practice, microthrombocytopenia is often not present or not appreciated in children with WAS. To develop an alternative method of differentiating WAS from ITP, we retrospectively reviewed all complete blood counts and measurements of immature platelet fraction (IPF) in 18 subjects with WAS and 38 subjects with a diagnosis of ITP treated at our hospital. Examination of peripheral blood smears revealed a wide range of platelet sizes in subjects with WAS. Mean platelet volume (MPV) was not reported in 26% of subjects, and subjects in whom MPV was not reported had lower platelet counts than did subjects in whom MPV was reported. Subjects with WAS had a lower IPF than would be expected for their level of thrombocytopenia, and the IPF in subjects with WAS was significantly lower than in subjects with a diagnosis of ITP. Using logistic regression, we developed and validated a rule based on platelet count and IPF that was more sensitive for the diagnosis of WAS than was the MPV, and was applicable regardless of the level of platelets or the availability of the MPV. Our observations demonstrate that MPV is often not available in severely thrombocytopenic subjects, which may hinder the diagnosis of WAS. In addition, subjects with WAS have a low IPF, which is consistent with the notion that a platelet production defect contributes to the thrombocytopenia of WAS. Knowledge of this detail of WAS pathophysiology allows to differentiate WAS from ITP with increased sensitivity, thereby allowing a physician to spare children with WAS from inappropriate treatment, and make definitive therapy available in a timely manner.

Mathematical model of platelet turnover in thrombocytopenic and nonthrombocytopenic preterm neonates

Neonatal thrombocytopenia affects 22-35% of all neonates admitted to neonatal intensive care units. The purpose of this study was to develop a mathematical model for characterizing platelet (PLT) kinetics in thrombocytopenic preterm neonates. Immature PLT fraction (IPF) and PLT counts were measured for up to 35 days after birth in 27 very low birth weight preterm neonates. PLT transfusions were administered to 8 of the 27 (24%) subjects. The final model included a series of four transit compartments to mimic the production and survival of IPF and PLT. Model parameters were estimated using nonlinear mixed effects modeling with the maximum likelihood expectation maximization algorithm. The model adequately captured the diverse phenotypes expressed by individual subject profiles. Typical population survival values for IPF and PLT life spans in nonthrombocytopenic patients were estimated at 0.912 and 10.7 days, respectively. These values were significantly shorter in thrombocytopenic subjects, 0.429 and 2.56 days, respectively. The model was also used to evaluate the influence of growth and laboratory phlebotomy loss on the time course of IPF and PLT counts. Whereas incorporating body weight was essential to correct for expanding blood volume due to growth, phlebotomy loss, a possible covariate, did not significantly influence PLT kinetics. This study provides a platform for identifying potential covariates that influence the interindividual variability in model parameters regulating IPF and PLT kinetics and for evaluating future pharmacological therapies for treating thrombocytopenic neonates.

Do immature platelet levels in chest pain patients presenting to the emergency department aid in the diagnosis of acute coronary syndrome?

INTRODUCTION

Early and accurate identification of acute coronary syndrome (ACS) vs. noncardiac chest pain in patients presenting to the emergency department (ED) is problematic and new diagnostic markers are needed. Previous studies reported that elevated mean platelet volume (MPV) is associated with ACS and predictive of cardiovascular risk. MPV is closely related to the immature platelet fraction (IPF), and recent studies have suggested that IPF may be a more sensitive marker of ACS than MPV. The objective of the present study was to determine whether the measurement of IPF assists in the diagnosis of ACS in patients presenting to the ED with chest pain.

METHODS

In this single-center, prospective, cross-sectional study, adult patients presenting to the ED with chest pain and/or suspected ACS were considered for enrollment. Blood samples from 236 ACS-negative and 44 ACS-positive patients were analyzed in a Sysmex XE-2100 for platelet count, MPV, IPF, and the absolute count of immature platelets (IPC).

RESULTS

Total platelet counts, MPV, IPF, and IPC were not statistically different between ACS-negative and ACS-positive patients. The IPF was 4.6 ± 2.7% and 5.0 ± 2.8% (mean ± SD, P = 0.24), and the IPC was 10.0 ± 4.6 and 11.5 ± 7.5 × 10(3) /μL (P = 0.27) for ACS-negative and ACS-positive patients, respectively.

CONCLUSION

In 280 patients presenting to the ED with chest pain and/or suspected ACS, no differences in IPF, IPC or MPV were observed in ACS-negative vs. ACS-positive patients, suggesting that these parameters do not assist in the diagnosis of ACS.

Beyond the platelet count: immature platelet fraction and thromboelastometry correlate with bleeding in patients with immune thrombocytopenia

Platelet counts (PC) estimate bleeding risk in Immune Thrombocytopenia (ITP). We investigated whether measures of thromboelastometry and absolute immature platelet fraction (A-IPF) would correlate better with acute bleeding score (ABS) than PC or mean platelet volume (MPV). Simultaneous determination of ABS, complete blood count and thromboelastometry was performed in 141 ITP patients; 112 underwent A-IPF testing. Subgroup analyses were performed for paediatric subjects, PC <60 × 10(9) /l and <30 × 10(9) /l. PC significantly inversely correlated with ABS in all subjects, PC <30 × 10(9) /l and total paediatric cohort. MPV did not correlate with ABS in any subgroup. Thromboelastometry measures of clot firmness, but not PC, significantly correlated with ABS in all subjects with PC <60 × 10(9) /l, and children with PC <60 × 10(9) /l and <30 × 10(9) /l. A-IPF demonstrated stronger correlation with ABS than did PC among all subjects, those with PC <60 × 10(9) /l, all children and children with PC <30 × 10(9) /l (r = -0·37; r = -0·34; r = -0·44; r = -0·60) versus ABS with PC (r = -0·36; ns; r = -0·32; ns). Stronger correlations of both thromboelastometry measures of clot firmness and A-IPF than PC with ABS suggest factors beyond PC, i.e. related to platelet function, contribute to ITP bleeding pathophysiology. Thromboelastometry, A-IPF and ABS can be incorporated into routine or acute visits.

Immature platelet fraction measured on the Sysmex XN hemocytometer predicts thrombopoietic recovery after autologous stem cell transplantation

Objectives

A period of thrombocytopenia is common after stem cell transplantation (SCT). To prevent serious bleeding complications, prophylactic platelet transfusions are administered. Previous studies have shown that a rise in immature platelets precedes recovery of platelet count. Our aim was to define a cutoff value for immature platelets predicting thrombopoietic recovery within 2 d.

Methods

Hematological parameters were measured on the Sysmex XN hemocytometer. We calculated reference change values (RCV) for platelets in eight healthy individuals as marker for platelet recovery. To define a cutoff value, we performed ROC analysis using data from 16 autologous SCT patients.

Results

RCV for platelet concentration was 14.1%. Platelet recovery was observed 13 (median; range 9–31) days after SCT. Increase in immature platelet fraction (IPF) before platelet recovery was seen in all autologous SCT patients. Optimal cutoff IPF was found to be 5.3% for platelet recovery within 2 d (specificity 0.98, sensitivity 0.47, positive predictive value 0.93).

Conclusions

We identified an optimal cutoff value for IPF 5.3% to predict platelet recovery after autologous SCT within 2 d. Implementing this cutoff value in transfusion strategy may reduce the number of prophylactic platelet transfusions.

Examination of the percentage of immature platelet fraction in term and preterm infants at birth

Background:

Reticulated platelets (RPs) are newly synthesized platelets. Recently, an automatic method was established to detect RPs as a percentage of the immature platelet fraction (IPF%). Although, neonates often develop thrombocytopenia at some time during their hospitalization, the details of IPF% in neonates remain unclear. We, therefore, studied the relations between IPF% and other factors to gain a more detailed understanding of IPF% in neonates.

Methods:

The following clinical data were obtained from the medical records of 105 neonates who met our inclusion criteria: Gestational age, birth weight, IPF% and platelet count of neonatal peripheral blood at birth, and perinatal data. The subjects were divided into three groups: Group A, birth weight standard deviation score (SDS) ≥ −2 standard deviation (SD) and ≤ +2 SD; Group S, < −2 SD; and Group L, > +2 SD.

Results:

IPF% correlated negatively with platelet count at birth in the whole study population. IPF% was 2.8 ± 1.3% in term neonates, and IPF correlated negatively with gestational age and birth weight. Platelet count correlated positively with birth weight SDS in the whole study population and in Group S. IPF% correlated negatively with birth weight SDS in the whole study population and in Group S. In neonates with a platelet count below 25 × 10⁴/μl, IPF% correlated negatively with platelet count. Among other neonates, however, IPF% remained almost constant.

Conclusion:

Monitoring of IPF% is useful for estimating the function of thrombocytopoiesis in neonates and preterm infants.

Thrombocytopenia in patients with hepatitis B virus-related chronic hepatitis: evaluation of the immature platelet fraction

The immature platelet fraction (IPF) measures the number of reticulated platelets in peripheral blood, and can be used to help determine if thrombocytopenia is secondary to low-platelet production or increased platelet turnover. The aim of this study was to determine whether abnormalities in the IPF were associated with thrombocytopenia in patients with hepatitis B virus-related chronic hepatitis (CHB). One hundred fifty-six patients with chronic hepatitis B, including 80 thrombocytopenia, 76 without thrombocytopenia, and 48 healthy controls were enrolled in the study. The IPF percentages (IPF%) were measured using a XE-2100 multiparameter automatic hematology analyzer. We demonstrated that in the thrombocytopenic group, the IPF% was significantly increased compared with that in healthy controls and the non-thrombocytopenic group (both p < 0.001). Multivariate analysis demonstrated that IPF%, splenomegaly, and the model for end-stage liver disease score were independent predictors for thrombocytopenia (both p < 0.001). High IPF% during the course of thrombocytopenia suggests that platelet destruction/sequestration due to hypersplenism is a major factor contributing to thrombocytopenia in patients with CHB.