What It Takes To Be a Platelet: Evolving Concepts in Platelet Production.

Platelets are among the most abundant cells within the circulation. Given that the platelet lifespan is 7 to 10 days in humans, a constant production of around 100 billion platelets per day is required. Platelet production from precursor cells called megakaryocytes is one of the most enigmatic processes in human biology. Although it has been studied for over a century, there is still controversy about the exact mechanisms leading to platelet release into circulation. The formation of proplatelet extensions from megakaryocytes into bone marrow sinusoids is the best-described mechanism explaining the origin of blood platelets. However, using powerful imaging techniques, several emerging studies have recently raised challenging questions in the field, suggesting that small platelet-sized structures called buds might also contribute to the circulating platelet pool. How and whether these structures differ from microvesicles or membrane blebs, which have previously been described to be released from megakaryocytes, is still a matter of discussion. In this review, we will summarize what the past and present have revealed about platelet production and whether mature blood platelets might emerge via different mechanisms.

Thrombocytopenia Independently Leads to Changes in Monocyte Immune Function.

BACKGROUND: While platelets have well-studied hemostatic functions, platelets are immune cells that circulate at the interface between the vascular wall and white blood cells. The physiological implications of these constant transient interactions are poorly understood. Activated platelets induce and amplify immune responses, but platelets may also maintain immune homeostasis in healthy conditions, including maintaining vascular integrity and T helper cell differentiation, meaning that platelets are central to both immune responses and immune quiescence. Clinical data have shown an association between low platelet counts (thrombocytopenia) and immune dysfunction in patients with sepsis and extracorporeal membrane oxygenation, further implicating platelets as more holistic immune regulators, but studies of platelet immune functions in nondisease contexts have had limited study. METHODS: We used in vivo models of thrombocytopenia and in vitro models of platelet and monocyte interactions, as well as RNA-seq and ATAC-seq (assay for transposase-accessible chromatin with sequencing), to mechanistically determine how resting platelet and monocyte interactions immune program monocytes. RESULTS: Circulating platelets and monocytes interact in a CD47-dependent manner to regulate monocyte metabolism, histone methylation, and gene expression. Resting platelet-monocyte interactions limit TLR (toll-like receptor) signaling responses in healthy conditions in an innate immune training-like manner. In both human patients with sepsis and mouse sepsis models, thrombocytopenia exacerbated monocyte immune dysfunction, including increased cytokine production. CONCLUSIONS: Thrombocytopenia immune programs monocytes in a manner that may lead to immune dysfunction in the context of sepsis. This is the first demonstration that sterile, endogenous cell interactions between resting platelets and monocytes regulate monocyte metabolism and pathogen responses, demonstrating platelets to be immune rheostats in both health and disease.

Shear Forces Induced Platelet Clearance Is a New Mechanism of Thrombocytopenia.

BACKGROUND: Thrombocytopenia has been consistently described in patients with extracorporeal membrane oxygenation (ECMO) and associated with poor outcome. However, the prevalence and underlying mechanisms remain largely unknown, and a device-related role of ECMO in thrombocytopenia has been hypothesized. This study aims to investigate the mechanisms underlying thrombocytopenia in ECMO patients. METHODS: In a prospective cohort of 107 ECMO patients, we investigated platelet count, functions, and glycoprotein shedding. In an ex vivo mock circulatory ECMO loop, we assessed platelet responses and VWF (von Willebrand factor)-GP Ibα (glycoprotein Ibα) interactions at low- and high-flow rates, in the presence or absence of red blood cells. The clearance of human platelets subjected or not to ex vivo perfusion was studied using an in vivo transfusion model in NOD/SCID (nonobese diabetic/severe combined Immunodeficient) mice. RESULTS: In ECMO patients, we observed a time-dependent decrease in platelet count starting 1 hour after device onset, with a mean drop of 7%, 35%, and 41% at 1, 24, and 48 hours post-ECMO initiation (P=0.00013, P<0.0001, and P<0.0001, respectively), regardless of the type of ECMO. This drop in platelet count was associated with a decrease in platelet GP Ibα expression (before: 47.8±9.1 versus 24 hours post-ECMO: 42.3±8.9 mean fluorescence intensity; P=0.002) and an increase in soluble GP Ibα plasma levels (before: 5.6±3.3 versus 24 hours post-ECMO: 10.8±4.1 µg/mL; P<0.0001). GP Ibα shedding was also observed ex vivo and was unaffected by (1) red blood cells, (2) the coagulation potential, (3) an antibody blocking VWF-GP Ibα interaction, (4) an antibody limiting VWF degradation, and (5) supraphysiological VWF plasma concentrations. In contrast, GP Ibα shedding was dependent on rheological conditions, with a 2.8-fold increase at high- versus low-flow rates. Platelets perfused at high-flow rates before being transfused to immunodeficient mice were eliminated faster in vivo with an accelerated clearance of GP Ibα-negative versus GP Ibα-positive platelets. CONCLUSIONS: ECMO-associated shear forces induce GP Ibα shedding and thrombocytopenia due to faster clearance of GP Ibα-negative platelets. Inhibiting GP Ibα shedding could represent an approach to reduce thrombocytopenia during ECMO.

Prognostic performance of non-invasive tests for portal hypertension is comparable to that of hepatic venous pressure gradient.

BACKGROUND & AIMS: Non-invasive tests to assess the probability of clinically significant portal hypertension (CSPH) - including the ANTICIPATE±NASH models based on liver stiffness measurement and platelet count±BMI, and the von Willebrand factor antigen to platelet count ratio (VITRO) - have fundamentally changed the management of compensated advanced chronic liver disease (cACLD). However, their prognostic utility has not been compared head-to-head to the gold standard for prognostication in cACLD, i.e. the hepatic venous pressure gradient (HVPG). METHODS: Patients with cACLD (liver stiffness measurement ≥10 kPa) who underwent advanced characterization via same-day HVPG/non-invasive test assessment from 2007-2022 were retrospectively included. Long-term follow-up data on hepatic decompensation was recorded. RESULTS: Four hundred and twenty patients with cACLD of varying etiologies, with a CSPH prevalence of 67.6%, were included. The cumulative incidence of hepatic decompensation at 1 and 2 years was 4.7% and 8.0%, respectively. HVPG, VITRO, and ANTICIPATE±NASH-CSPH-probability showed similar time-dependent prognostic value (AUROCs 0.683-0.811 at 1 year and 0.699-0.801 at 2 years). In competing risk analyses adjusted for MELD score and albumin, HVPG (adjusted subdistribution hazard ratio [aSHR] 1.099 [95% CI 1.054-1.150] per mmHg; p <0.001), or VITRO (aSHR 1.134 [95% CI 1.062-1.211] per unit; p <0.001), or ANTICIPATE±NASH-CSPH-probability (aSHR 1.232 [95% CI 1.094-1.387] per 10%; p <0.001) all predicted first decompensation during follow-up. Previously proposed cut-offs (HVPG ≥10 mmHg vs. <10 mmHg, VITRO ≥2.5 vs. <2.5, and ANTICIPATE-CSPH probability ≥60% vs. <60%) all accurately discriminated between patients at negligible risk and those at substantial risk of hepatic decompensation. CONCLUSIONS: The prognostic performance of ANTICIPATE±NASH-CSPH-probability and VITRO is comparable to that of HVPG, supporting their utility for identifying patients who may benefit from medical therapies to prevent first hepatic decompensation. IMPACT AND IMPLICATIONS: Non-invasive tests have revolutionized the diagnosis and management of clinically significant portal hypertension in patients with compensated advanced chronic liver disease (cACLD). However, limited data exists regarding the prognostic utility of non-invasive tests in direct comparison to the gold standard for prognostication in cACLD, i.e. the hepatic venous pressure gradient. In our study including 420 patients with cACLD, the ANTICIPATE±NASH model and VITRO yielded similar AUROCs to hepatic venous pressure gradient for hepatic decompensation within 1 to 2 years. Thus, non-invasive tests should be applied and updated in yearly intervals in clinical routine to identify patients at short-term risk, thereby identifying patients who may benefit from treatment aimed at preventing hepatic decompensation.

The importance of ABO in platelet refractoriness, an often overlooked option.

ABO-non-identical (ni) platelets provide less of an increase in platelet count and may increase the length of patient transfusions. The paper by Han and Badami showed that ABO-ni platelets may be a risk factor for immune platelet transfusion refractoriness. Commentary on: Han et al. ABO non-identical platelet transfusions, immune platelet refractoriness and platelet support. Br J Haematol 2024;204:2097-2102.

The use of splenic embolization in immune thrombocytopenia: A systematic review and meta-analysis.

The effectiveness of splenic embolization (SE) in treating refractory immune thrombocytopenia (ITP) remains uncertain. A systematic literature review was undertaken to assess the effectiveness and safety of SE in treating both paediatric and adult patients with ITP. We conducted an extensive search employing predefined criteria. We extracted platelet counts at baseline and at multiple intervals following SE, along with details of the proportion of embolized spleen parenchyma and the proportion of patients exhibiting complete or partial platelet count responses. We identified nine eligible reports for the analysis of effectiveness (228 patients) and 15 reports for the safety analysis (151 patients). Pooled estimates of complete response (platelet count >100 × 109/L) and overall response (platelet count >30 × 109/L) were 50.1% (95% CI: 38-62.3) and 74.4% (95% CI: 64.9-83.9) respectively. Most studies applied an embolization of at least 60% of the spleen parenchyma. Nearly all the patients suffered from mild adverse events (AEs), 1.3% suffered from serious AEs and one patient died (0.7%). In conclusion, SE resulted in an overall response rate in 74.4% of patients with ITP. However, this finding derives from uncontrolled studies of low to moderate quality.

Association of a decreased platelet count with poor survival in patients with adult secondary hemophagocytic lymphohistiocytosis.

We aimed to examine the association between baseline platelet count (PLT) and the prognosis of adult secondary hemophagocytic lymphohistiocytosis (sHLH). Data from 292 patients with pretreatment platelet counts were retrospectively analysed from January 2016 to December 2020. We categorized platelet count into quartiles. Multivariable Cox proportional hazards models and restricted cubic splines (RCS) were used to evaluate the relationship between platelet count and mortality. During a median follow-up of 53 (interquartile ranges, 17-223) days, a total of 208 deaths occurred. After adjusting for multiple variables, a non-linear and inverse relationship was observed between platelet count and mortality in sHLH patient (P for nonlinearity=0.002). For non- lymphoma-associated haemophagocytic lymphohistiocytosis (non-LHLH), a similar curve was also observed (P for nonlinearity =0.028). Decreased PLT (PLT Q4) was associated with an increased risk of mortality (adjusted hazard ratio: 1.97; 95% confidence interval: 1.28-3.04; Ptrend =0.005). Similar results were observed in the LHLH subgroup (adjusted hazard ratio: 1.84; 95% confidence interval: 1.05-3.24; Ptrend =0.024) but not in the non-LHLH subgroup (Ptrend =0.266). Baseline platelet count demonstrated a nonlinear and inverse association with an increased risk of mortality among adult sHLH patients. This method is used to identify sHLH patients with inferior overall survival due to its low cost and universal availability.

Risk factors of early disease progression and decreased survival for multiple myeloma patients after upfront autologous stem cell transplantation.

Multiple myeloma (MM) stands as the second most prevalent hematological malignancy, constituting approximately 10% of all hematological malignancies. Current guidelines recommend upfront autologous stem cell transplantation (ASCT) for transplant-eligible MM patients. This study seeks to delineate factors influencing post-ASCT outcomes in MM patients. Our cohort comprised 150 MM patients from Taipei Veterans General Hospital, with progression-free survival (PFS) as the primary endpoint and overall survival (OS) as the secondary endpoint. A Cox proportional hazards model was employed to discern potential predictive factors for survival. ASCT age ≥ 65 (hazard ratio [HR] 1.94, 95% confidence interval [CI] 1.08-3.47) and the presence of extramedullary disease (HR 2.53, 95% CI 1.53-4.19) negatively impacted PFS. Conversely, treatment response ≥ VGPR before ASCT (HR 0.52, 95% CI 0.31-0.87) and total CD34+ cells collected ≥ 4 × 106 cells/kg on the first stem cell harvesting (HR 0.52, 95% CI 0.32-0.87) were positively associated with PFS. For OS, patients with ISS stage III (HR 2.06, 95% CI 1.05-4.04), the presence of extramedullary disease (HR 3.92, 95% CI 2.03-7.58), light chain ratio ≥ 100 before ASCT (HR 7.08, 95% CI 1.45-34.59), post-ASCT cytomegalovirus infection (HR 9.43, 95% CI 3.09-28.84), and a lower conditioning melphalan dose (< 140 mg/m2; HR 2.75, 95% CI 1.23-6.17) experienced shorter OS. In contrast, post-ASCT day + 15 absolute monocyte counts (D15 AMC) > 500/µl (HR 0.36, 95% CI 0.17-0.79) and post-ASCT day + 15 platelet counts (D15 PLT) > 80,000/µl (HR 0.48, 95% CI 0.24-0.94) were correlated with improved OS. Significantly, early PLT and AMC recovery on day + 15 predicting longer OS represents a novel finding not previously reported. Other factors also align with previous studies. Our study provides real-world insights for post-ASCT outcome prediction beyond clinical trials.

Investigation of homocysteine, D-dimer and platelet count levels as potential predictors of thrombosis risk in COVID-19 patients.

Thrombosis plays an important role in induction of Coronavirus disease 19 (COVID-19) complications including heart attack and stroke. Reliable biomarkers are needed to predict thrombosis risk for better management and improve patient outcomes. This study aimed to investigate the relationship between homocysteine, a thrombosis-related biomarker, and other thrombosis-related parameters, such as D-dimer and platelet count with disease outcome in COVID-19 patients. This case-control study including 50 intensive care unit hospitalized patients with Covid-19 with a positive RT-PCR test for SARS-CoV-2 infection and 50 healthy individuals as a control group was conducted. Both groups were matched for age and body mass index (BMI) and had no history of underlying diseases such as cardiovascular, liver, kidney or smoking. Blood samples were collected from both groups to measure serum homocysteine, platelet count and D-dimer levels. Data were analyzed using GraphPad Prism version 8.3 software. The study found no statistically significant difference in homocysteine levels between COVID-19 patients and the control group. However, D-dimer levels were significantly higher in the patient group. Platelet count analysis revealed a significant difference between patients who died and those who were discharged from the hospital (P < 0.05). Despite previous studies suggesting a link between homocysteine and thrombosis, this study found no significant difference in homocysteine levels between COVID-19 patients and the control group. The significantly elevated D-dimer levels in the death group patient suggest that D-dimer and thrombocytopenia may be more reliable predictors of thrombosis and worse outcome in COVID-19 patients without underlying diseases.

A novel haemodilution chip mounted on the total thrombus-formation analysis system, a flow chamber system, enables stable analysis of platelet products under low platelet concentration/high shear conditions.

BACKGROUND AND OBJECTIVES: The total thrombus-formation analysis system (T-TAS) can quantitatively analyse the contribution of platelets to haemostasis using reconstituted blood samples. However, it is unsuitable in cases with low platelet counts. We introduced a haemodilution (HD) chip with a shallow chamber depth, adapted to low platelet counts and high shear conditions (1500 s-1). MATERIALS AND METHODS: Blood samples were prepared by mixing red blood cell products, standard human plasma and platelet products; the final platelet count was 50 × 103/µL. Aggregation tests were performed by using the aggregation inducers collagen, adenosine diphosphate (ADP) and ristocetin. Samples with 2-, 4- and 9-day-old platelet products (N = 10) were evaluated. RESULTS: The HD chip enabled the stable analysis of the haemostatic function of all samples at a platelet count of 50 × 103/µL. Haemostatic function was correlated with ADP aggregation (time to 10 kPa [T10]: r = -0.53; area under the curve for 30 min: r = 0.40) and storage period (T10: r = 0.44). CONCLUSION: The HD chip-mounted T-TAS can stably analyse haemostatic function under low platelet counts and high shear conditions; this approach is expected to serve as a bridge to in vivo haemostatic tests with experimental animals.

Risk-based and individualised management of bleeding and thrombotic events in adults with primary immune thrombocytopenia (ITP).

Although bleeding is one of the main symptoms of primary immune thrombocytopenia (ITP), risk factors for bleeding have yet to be fully established. Low platelet count (PC; <20-30 × 109 /L) is generally indicative of increased risk of bleeding. However, PC and bleeding events cannot be fully correlated; many other patient- and disease-related factors are thought to contribute to increased bleeding risk. Furthermore, even though ITP patients have thrombocytopenia and are at increased risk of bleeding, ITP also carries higher risk of thrombotic events. Factors like older age and certain ITP treatments are associated with increased thrombotic risk. Women's health in ITP requires particular attention concerning haemorrhagic and thrombotic complications. Management of bleeding/thrombotic risk, and eventually antithrombotic therapies in ITP patients, should be based on individual risk profiles, using a tailored, patient-centric approach. Currently, evidence-based recommendations and validated tools are lacking to support decision-making and help clinicians weigh risk of bleeding against thrombosis. Moreover, evidence is lacking about optimal PC for achieving haemostasis in invasive procedures settings. Further research is needed to fully define risk factors for each event, enabling development of comprehensive risk stratification approaches. This review discusses risk-based and individualised management of bleeding and thrombosis risk in adults with primary ITP.

Preoperative platelet count as an independent predictor of long-term outcomes among patients undergoing resection for intrahepatic cholangiocarcinoma.

BACKGROUND AND OBJECTIVES: An elevated platelet count may reflect neoplastic and inflammatory states, with cytokine-driven overproduction of platelets. The objective of this study was to evaluate the prognostic utility of high platelet count among patients undergoing curative-intent liver surgery for intrahepatic cholangiocarcinoma (ICC). METHODS: An international, multi-institutional cohort was used to identify patients undergoing curative-intent liver resection for ICC (2000-2020). A high platelet count was defined as platelets >300 *109/L. The relationship between preoperative platelet count, cancer-specific survival (CSS), and overall survival (OS) was examined. RESULTS: Among 825 patients undergoing curative-intent resection for ICC, 139 had a high platelet count, which correlated with multifocal disease, lymph nodes metastasis, poor to undifferentiated grade, and microvascular invasion. Patients with high platelet counts had worse 5-year (35.8% vs. 46.7%, p = 0.009) CSS and OS (24.8% vs. 39.8%, p < 0.001), relative to patients with a low platelet count. After controlling for relevant clinicopathologic factors, high platelet count remained an adverse independent predictor of CSS (HR = 1.46, 95% CI 1.02-2.09) and OS (HR = 1.59, 95% CI 1.14-2.22). CONCLUSIONS: High platelet count was associated with worse tumor characteristics and poor long-term CSS and OS. Platelet count represents a readily-available laboratory value that may preoperatively improve risk-stratification of patients undergoing curative-intent liver resection for ICC.

Abnormal platelet parameters in inflammatory bowel disease: a systematic review and meta-analysis.

BACKGROUND: Platelet dysfunction plays a critical role in the pathogenesis of inflammatory bowel disease (IBD). Despite clinical observations indicating abnormalities in platelet parameters among IBD patients, inconsistencies persist, and these parameters lack standardization for diagnosis or clinical assessment. METHODS: A comprehensive search was conducted in the PubMed, Embase, Web of Science, and Cochrane Library databases for relevant articles published up to December 16th, 2023. A random-effects model was employed to pool the weighted mean difference (WMD) and 95% confidence interval (95% CI) of platelet count (PLT), mean platelet volume (MPV), platelet distribution width (PDW), and plateletcrit (PCT) between IBD patients and healthy controls, and subgroup analyses were performed. RESULTS: The meta-analysis included 79 articles with 8,350 IBD patients and 13,181 healthy individuals. The results revealed significantly increased PLT and PCT levels (WMD: 69.910, 95% CI: 62.177, 77.643 109/L; WMD: 0.046%, 95% CI: 0.031%, 0.061%), and decreased MPV levels (WMD: -0.912, 95% CI: -1.086, -0.739 fL) in IBD patients compared to healthy individuals. No significant difference was found in PDW between the IBD and control groups (WMD: -0.207%, 95% CI: -0.655%, 0.241%). Subgroup analysis by disease type and disease activity showed no change in the differences for PLT, PCT, and MPV in the ulcerative colitis and Crohn's disease groups, as well as the active and inactive groups. Notably, the active group exhibited significantly lower PDW levels than the control group (WMD: -1.138%, 95% CI: -1.535%, -0.741%). CONCLUSIONS: Compared with healthy individuals, IBD patients display significantly higher PLT and PCT and significantly lower MPV. Monitoring the clinical manifestations of platelet abnormalities serves as a valuable means to obtain diagnostic and prognostic information. Conversely, proactive measures should be taken to prevent the consequences of platelet abnormalities in individuals with IBD. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42023493848.

Performance evaluation of a novel platelet count parameter, hybrid platelet count, on the BC-780 automated hematology analyzer.

OBJECTIVES: Automated hematology analysis is expected to improve the performance of platelet counting. We evaluated the performance of a new platelet counting, hybrid (PLT-H) and also impedance (PLT-I) and optical (PLT-O) on the BC-780 automated hematology analyzer compared to the international reference method (IRM) in blood samples with thrombocytopenic and platelet interference. METHODS: The basic platelet count performance of the BC-780 automated hematology analyzer was evaluated according to the requirements of the Clinical Laboratory and Standards Institute (CLSI) Document H26-A2. Additionally, the thrombocytopenic (low PLT count) blood samples and the platelet interference blood samples including fragmented red blood cells (RBCs), microcytes or small RBCs, and giant platelets were determined with the BC-780 hematology analyzer compared to the IRM. RESULTS: Blank counting and the carry-over contamination rate of platelet count using the BC-780 both met the manufacturers' claim. For both 123 thrombocytopenic and 232 platelet interference blood samples (72 fragmented RBCs, 91 microcytes and 51 giant platelets), all three platelet counting methods exhibited high comparability with the IRM (the lowest correlation (r)=0.916). Interestingly, the comparability of PLT-H (r=0.928-0.986) with the IRM was better than that of PLT-I (r=0.916-0.979). CONCLUSIONS: The performance of PLT-H in the BC-780 met the manufacturer's specifications. PLT-H exhibits better reproducibility than did PLT-I, correlates well with the PLT-O for thrombocytopenic samples and demonstrates good anti-interference ability. PLT-H counting is therefore recommended as a zero-cost alternative platelet counting method for platelet interference samples in clinical settings.

Association between postoperative nadir platelet count and postoperative cardiovascular complications following septal myectomy in patients with hypertrophic cardiomyopathy: a retrospective cohort study.

BACKGROUND: Platelet count is associated with cardiovascular risk and mortality in several cardiovascular diseases, but the association of the nadir platelet counts post-septal myectomy with the cardiovascular complication risk in hypertrophic obstructive cardiomyopathy patients remains unclear. METHODS: This retrospective cohort study reviewed all adult patients who underwent septal myectomy at a single tertiary referral center over a 5-year period. Postoperative nadir platelet count was defined as the lowest platelet count in the first 4 postoperative days or until hospital discharge. The composite outcome included cardiovascular death, myocardial infarction, heart failure, malignant arrhythmia, cardiac tamponade, and major bleeding events within 30 days postoperatively. Univariable and multivariable logistic regression and restricted cubic spline models were used to assess the association between postoperative nadir platelet count and the 30-day postoperative cardiovascular complication risk. RESULTS: Among the 113 enrolled patients, 23 (20.4%) developed cardiovascular events within 30 days postoperatively. The incidence of postoperative cardiovascular complications was significantly higher in patients with a nadir platelet count ≤ 99 × 109/L than in those with a nadir platelet count > 99 × 109/L (33.3% vs. 7.1%, crude risk ratio: 4.67, 95% confidence interval: 1.69-12.85, P < 0.001). Multivariable logistic regression revealed that postoperative nadir platelet count was negatively associated with 30-day postoperative cardiovascular complications (adjusted odds ratio: 0.97; 95% confidence interval: 0.95-0.99; P = 0.005) and the association was linear (Pnonlinearity = 0.058) after full adjustment. The association between nadir platelet count and cardiovascular complications within 30 days post-surgery was consistent in all predefined subgroups (Pinteraction > 0.05). CONCLUSION: The postoperative nadir platelet count was significantly associated with the 30-day post-myectomy risk of cardiovascular complications in hypertrophic obstructive cardiomyopathy patients. TRIAL REGISTRATION: This trial was registered at ClinicalTrials.gov (NCT04275544).

Platelet function testing: Update on determinant variables and permissive windows using a platelet-count-based device.

While there are various aspects of platelet biology that can be studied in the lab (i.e. adhesion, degranulation, integrin activation), the master test for platelet function is that which gives a measure of the platelet aggregation capacity upon stimulation with an agonist. Platelet function testing is necessary for the diagnosis of platelet disorders and the monitoring of patients receiving anti-platelet treatments. Furthermore, it becomes relevant in the quality control of platelet concentrates for transfusion purposes, especially considering the global concern about long term storage, other forms of storage (i.e. cryopreservation, lyophilization), and the impact of Pathogen Reduction Treatments (PRTs) on platelet performance upon transfusion. However, it has been acknowledged as technically difficult and demanding, since a fine platelet function test must be carried out under specific conditions. Still, there might be occasions that preclude the platelet function testing abiding to the gold standard requirements, thus, leaving us with the necessity to redefine which variables may condition or limit the analysis of platelet function testing. In the present manuscript, we test different variables (such as the anticoagulant used or the time elapsed since extraction) and the possibility to reconstitute blood prior to platelet function analysis. This study aims to provide windows of action at the diagnostics lab, especially when not all of the recommended procedures and conditions can be followed: for example, when a sample is sent from a long distance, when there is a limitation on blood extraction volume or when certain parameters (platelet count) preclude reliable test results.

Real-life clinical practice in Spain in the setting of new drug availability for ITP treatment. A Delphi-based Spanish expert panel consensus.

Immune thrombocytopenia (ITP) is a common autoimmune hematological disorder. Despite this, diagnosis is still challenging due to clinical heterogeneity and the lack of a specific diagnostic test. New findings in the pathology and the availability of new drugs have led to the development of different guidelines worldwide. In the present study, the Delphi methodology has been used to get a consensus on the management of adult patients with ITP in Spain and to help in decision-making. The Delphi questionnaire has been designed by a scientific ad hoc committee and has been divided into 13 topics, with a total of 127 items, covering the maximum possible scenarios for the management of ITP. As a result of the study, a total consensus of 81% has been reached. It is concluded that this Delphi consensus provides practical recommendations on topics related to diagnosis and management of ITP patients to help doctors to improve outcomes. Some aspects remain unclear, without consensus among the experts. Thus, more advances are needed to optimize ITP management.

What is the context? Immune thrombocytopenia (ITP) is a hematologic autoimmune disease characterized by accelerated destruction and inadequate production of platelets mediated by autoantibodies (platelet count <100 × 10⁹ /L).Despite being a common condition, its heterogeneous clinical course makes its diagnosis and management still a challenge.In recent years, new molecules with different mechanisms of action have emerged for the treatment of ITP.Due to the increasing information about the pathology and its therapies, several international guidelines have recently been established to provide recommendations for the management and treatment of ITP.There are still many patient scenarios and disease aspects which are not addressed in the guidelines.What is new? Our Spanish ITP Expert Group has developed a Delphi consensus study to provide recommendations and promote standardization of the management of adult patients with ITP in Spain.The scientific committee defined 127 statements for consensus, corresponding to 13 chapters: (i) Diagnosis of ITP, (ii) First-line treatment, (iii) Second-line treatment, (iv) Treatment of refractory patients, (v) Follow-up, (vi) Emergency and surgery, (vii) ITP in the elderly, (viii) ITP in pregnancy, (ix) Anticoagulation and antiplatelet, (x) Secondary ITP, (xi) Quality of life, (xii) Discontinuation of TPO-RA, and (xiii) ITP and Covid.The total number of agreed statements achieved was 103, giving a final percentage of consensus in the Delphi questionnaire of 81%.What is the impact? This Delphi consensus provides recommendations based on real clinical practice data, regarding the diagnosis, treatment, and management of patients and scenarios in ITP to assist clinicians in addressing this disease and achieving optimal outcomes for the patient.

Effect of ferric citrate hydrate on fibroblast growth factor 23 and platelets in non-dialysis-dependent chronic kidney disease and non-chronic kidney disease patients with iron deficiency anemia.

BACKGROUND: Iron deficiency anemia (IDA) increases levels of C-terminal fibroblast growth factor 23 (cFGF23) and platelet count (PLT), each of which is associated with cardiovascular events. Therefore, we hypothesized that iron replacement with ferric citrate hydrate (FC) would decrease cFGF23 levels and PLT in patients with IDA. METHODS: In a randomized, open-label, multicenter, 24-week clinical trial, patients with non-dialysis-dependent chronic kidney disease (CKD) and non-CKD complicated by IDA (8.0 ≤ hemoglobin < 11.0 g/dL; and serum ferritin < 50 ng/mL [CKD]; < 12 ng/mL [non-CKD]) were randomized 1:1 to FC-low (500 mg: approximately 120 mg elemental iron/day) or FC-high (1000 mg: approximately 240 mg elemental iron/day). If sufficient iron replacement had been achieved after week 8, further treatment was discontinued. RESULTS: Seventy-three patients were allocated to FC-low (CKD n = 21, non-CKD n = 15) and FC-high (CKD n = 21, non-CKD n = 16). Regardless of CKD status, FC increased serum ferritin and transferrin saturation, did not change intact FGF23 or serum phosphorus, but decreased cFGF23. In FC-low group, median changes in cFGF23 from baseline to week 8 were -58.00 RU/mL in CKD and -725.00 RU/mL in non-CKD; in FC-high group, the median changes were -66.00 RU/mL in CKD and -649.50 RU/mL in non-CKD. By week 8, FC treatment normalized PLT in all patients with high PLT at baseline (>35.2 × 104/µL; FC-low: 1 CKD, 8 non-CKD; FC-high: 3 CKD, 8 non-CKD). CONCLUSION: Regardless of CKD status, iron replacement with FC decreased elevated cFGF23 levels and normalized elevated PLT in patients with IDA. CLINICAL TRIAL REGISTRATION NUMBER: jRCT2080223943.

Limited value of platelet-related markers in diagnosing periprosthetic joint infection.

OBJECTIVE: To evaluate the diagnostic values of serum platelet count (PC), mean platelet volume ratio (MPV), platelet count to mean platelet volume ratio (PVR), platelet to lymphocyte ratio (PLR), platelet to neutrophil ratio (PNR), PC/Albumin-globulin ratio (PC/AGR), and PC/C-reactive protein (PC/ CRP) in the diagnosis of periprosthetic joint infection (PJI). METHODS: The medical records were retrospectively analyzed of the 158 patients who had undergone hip or knee revisions from January 2018 to May 2022. Of them, 79 cases were diagnosed with PJI and 79 with aseptic loosening (AL). PJI was defined using the Musculoskeletal Infection Society criteria. The plasma levels of CRP, the erythrocyte sedimentation rate (ESR), PC, MPV, PVR, PLR, PNR, PC/AGR, and PC/CRP in the 2 groups were recorded and analyzed. In addition, tests were performed according to different joint types. The receiver operating characteristic curve was used to calculate the sensitivity and specificity of each indicator. The diagnostic value for each indicator was calculated according to the area under the curve (AUC). RESULTS: The PC, PVR, PLR and PC/AGR levels in the PJI group were significantly higher than those in the AL group, while PC/CRP levels were significantly lower (P < 0.001). The AUC for PC/CRP, and PC/AGR was 0.804 and 0.802, respectively, which were slightly lower than that of CRP (0.826) and ESR (0.846). ROC analysis for PC/CRP, and PC/AGR revealed a cut-off value of 37.80 and 160.63, respectively, which provided a sensitivity of 73.42% and 84.81% and a specificity of 75.95% and 65.82% for PJI. The area under the curve of PLR and PC was 0.738 and 0.702. The area under the curve values for PVR, PNR, and MPV were 0.672, 0.553, and 0.544, respectively. CONCLUSIONS: The results of this study suggest that PC, PLR, PC/CRP, and PC/AGR values do not offer significant advantages over ESR or CRP values when employed for the diagnosis of PJI. PVR, PNR, and MPV were not reliable in the diagnosis of PJI.

Skin graft surgery and its impact on platelet counts in Iranian burn patients: a non-randomized clinical trial.

BACKGROUND: Platelets are critical in maintaining homeostasis and immune response in burn patients. The concentration of platelets decreases in burn patients, and any intervention that increases serum platelet concentration can prevent serious consequences and patient death. The present study aimed to assess the impact of skin graft surgery on burn patients' platelet counts. METHODS: In this non-randomized clinical trial, 200 burn patients were investigated. The patients were recruited from the surgical ward of Imam Khomeini Teaching Hospital during the first six months of 2021. After completing the checklist, patients underwent skin graft surgery. Blood was taken from the patients during surgery in the operating room and on the third and fifth day after the surgery to check platelets. Data analysis was conducted using SPSS software (ver. 22.0). RESULTS: Most patients (63.5%) were male, and 73 (36.5%) were female. One hundred eighty-one patients (90.5%) had deep burns, and 19 (9.5%) had superficial burns. The mean burns percentage in the patients was 19.3 ± 15.4%, the lowest was 2%, and the highest was 90%. The most common burns were caused by flame (42%) and boiling water (30.5%). The patients' outcomes revealed that 6% gained complete recovery, 86.5% partial recovery, 2.5% showed transplant rejection, and 5% died. Mean platelet levels in deceased patients had an upward trend. The mean platelet counts of patients were elevated during surgery (289,855 ± 165,378), decreased three days after surgery (282,778 ± 317,310), and elevated again five days after surgery (330,375 ± 208,571). However, no significant difference was found between the mean platelet counts during surgery, the third and fifth days after surgery in patients undergoing skin grafts (P = 0.057). CONCLUSIONS: This study suggests that skin graft positively increases the patient's platelets. Further studies are needed to confirm the findings and elucidate the mechanism. Iranian Registry of Clinical Trial approval code (IRCT# IRCT20131112015390N8 & 06/01/2024).