Immature platelet fraction (IPF): A reliable tool to predict peripheral thrombocytopenia

Pretreatment Absolute Immature Platelet Count is a Promising Predictor of Response to Short-Term Dexamethasone Monotherapy or Combination Therapy in Newly Diagnosed Adult Primary Immune Thrombocytopenia

Reliable indicators that can predict drug responsiveness in primary immune thrombocytopenia (ITP) patients are urgent. We aimed to establish a reference interval of percentage of immature platelet fraction (IPF%) and absolute immature platelet count (A-IPC), and assess their efficacy in discriminating ITP patients from controls, especially their predictive value for responsiveness to drug treatment. We retrospectively studied 72 treatment-naive adult patients with ITP who received Dexamethasone monotherapy or combination therapy. Baseline (pretreatment) information was collected from medical records. Reference intervals for A-IPC and IPF% were established based on controls and their effectiveness in discriminating ITP patients from controls was assessed. Predictive value of pretreatment IPF% and A-IPC at four co-primary endpoints of treatment response in patients were investigated. The 95% reference intervals for A-IPC and IPF% were (2.7-15.6) × 109/L and 1.2%-7.3%, respectively. Both A-IPC and IPF% had excellent discrimination ability for ITP patients from controls. It showed highly statistically significant differences in pretreatment A-IPC for predicting treatment response at day 7 between responders and non-responders, but not at days 14, 21 and 28. Pretreatment A-IPC had the higher area under the ROC curve with a cut-off of 0.86 than that of IPF% with a cut-off of 14.5% in predicting the treatment response in ITP patients at day 7. Pretreatment A-IPC exhibited acceptable predictive power and could be a promising predictor of response to short-term Dexamethasone monotherapy or combination therapy at day 7 in ITP patients.

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.

Automated Detection of Dysplasia: Data Mining from Our Hematology Analyzers

Myelodysplastic syndromes (MDSs) are clonal hematopoietic diseases of the elderly, characterized by chronic cytopenia, ineffective and dysplastic hematopoiesis, recurrent genetic abnormalities and increased risk of progression to acute myeloid leukemia. Diagnosis on a complete blood count (CBC) can be challenging due to numerous other non-neoplastic causes of cytopenias. New generations of hematology analyzers provide cell population data (CPD) that can be exploited to reliably detect MDSs from a routine CBC. In this review, we first describe the different technologies used to obtain CPD. We then give an overview of the currently available data regarding the performance of CPD for each lineage in the diagnostic workup of MDSs. Adequate exploitation of CPD can yield very strong diagnostic performances allowing for faster diagnosis and reduction of time-consuming slide reviews in the hematology laboratory.

Experts' review: the emerging roles of romiplostim in immune thrombocytopenia (ITP)

INTRODUCTION

The management of ITP has in recent years been transformed from reliance on immunosuppressants and splenectomy to targeted therapy with thrombopoietin receptor agonists (TPO-RA) that directly stimulate platelet production in the bone marrow. This has reduced the long-term infective complications and toxicities associated with the use of potent immunosuppressants and splenectomy. The welltolerated romiplostim, itself a novel drug construct called peptibody, has established itself, alongside other TPO-RA as the preferred 2nd line therapy in major international guidelines on treatment of ITP.

AREAS COVERED

This review summarizes the data from early licensing trials of romiplostim and discusses the real-world experience to date, the unexpected emerging data on treatment-free long-term remission achieved using TPO-RA, and the case for its early introduction in the therapeutic pathway. The emerging risk of thrombosis is also discussed.

EXPERT OPINION

The use of romiplostim and other TPO-RA will be increasingly brought forward in the management pathway of ITP with the prospect of modifying the long-term outcome of the disease by increasing sustained treatment-free remission. With the prospect of several new targeted therapies been introduced into clinical practice, TPO-RA will likely be a key component of future combination therapies for difficult cases.

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.

Immature platelet dynamics correlate with ADAMTS13 deficiency and predict therapy response in immune-mediated thrombotic thrombocytopenic purpura

INTRODUCTION

Thrombotic thrombocytopenic purpura (TTP) requires prompt initiation of therapeutic plasma exchange (TPE) to avoid significant morbidity and mortality. ADAMTS13 activity testing defines TTP, however, at most institutions this is a send-out test and therapy is often initiated prior to measurement availability. We describe our experience looking at absolute immature platelet counts (A-IPC) in patients suspected with TTP at presentation and in response to therapy.

MATERIALS AND METHODS

Forty-eight patients treated for suspected TTP with A-IPC measure on admission and during hospitalization met inclusion criteria. Of these patients, sixteen had new-onset TTP (ADAMTS13 < 10%), ten were relapsing patients (first diagnosis prior to study period), and 22 were classified as non-TTP (ADAMTS13 ≥ 10%).

RESULTS

Patients with ADAMTS13 deficiency (TTP) had A-IPC different from those without deficiency. A-IPC of 1-2 × 10⁹/L at presentation had high sensitivity and specificity with a negative predictive value of 95.5 to 100%. Two-to-three-fold increases in A-IPC from count prior to TPE initiation was limited to ADAMTS13 deficient patients who was the group responding to therapy. Increases were higher in patients with new disease onset compared to relapsing patients (p = 0.018). Likewise, relapsing patients' A-IPC appeared dependent upon platelet count at time of relapse. A-IPC predicted and correlated with ADAMTS13 deficiency in new-onset TTP (p = 0.0002).

CONCLUSIONS

Only patients with A-IPC-fold increases responded to TPE with platelet count normalization. Our results represent a proof of concept that A-IPC measurements can supplement ADAMTS13 testing and determine response to TPE. Future studies are needed to establish ways to apply these findings in the setting of suspected TTP.

Immature platelets: a review of the available evidence

Immature platelets or reticulated platelets are newly released thrombocytes. They can be identified by their large size and high RNA cytoplasm concentration. Immature platelet fraction (IPF) represents the percentage of immature circulative platelets to the total number of platelets. The development of analytical standardization of this hematological parameter by new automated devices allowed a better exploration of its contribution in a context of thrombocytopenia. In fact, several studies had confirmed its clinical utility to differentiate immune thrombocytopenia from other causes of thrombocytopenia. IPF can also predict platelets recovery after chemotherapy and successful engraftment. In addition, immature platelets have shown utility in other diseases such as coronary artery diseases, bacterial infections and liver diseases. Despite all these advantages, immature platelet fraction can be increased in some cases of thrombocytopenia characterized by platelets hypoproduction. The aim of this review is to present the immature platelet fraction contribution in clinical practice.

Platelet Counting: Ugly Traps and Good Advice. Proposals from the French-Speaking Cellular Hematology Group (GFHC)

Despite the ongoing development of automated hematology analyzers to optimize complete blood count results, platelet count still suffers from pre-analytical or analytical pitfalls, including EDTA-induced pseudothrombocytopenia. Although most of these interferences are widely known, laboratory practices remain highly heterogeneous. In order to harmonize and standardize cellular hematology practices, the French-speaking Cellular Hematology Group (GFHC) wants to focus on interferences that could affect the platelet count and to detail the verification steps with minimal recommendations, taking into account the different technologies employed nowadays. The conclusions of the GFHC presented here met with a "strong professional agreement" and are explained with their rationale to define the course of actions, in case thrombocytopenia or thrombocytosis is detected. They are proposed as minimum recommendations to be used by each specialist in laboratory medicine who remains free to use more restrictive guidelines based on the patient’s condition.

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.