Risk factors for linezolid - induced haematological toxicity in patients: a retrospective study.

INTRODUCTION: This single-center, observational cohort study aimed to investigate the risk factors associated with linezolid-induced hematological toxicity by analyzing the linezolid trough concentration (Cmin) obtained from patients undergoing treatment between January 2020 and December 2021. METHODOLOGY: A total of 111 eligible individuals were included in the study, of which 47 were diagnosed with linezolid-induced thrombocytopenia and 18 were diagnosed with linezolid-induced hemoglobin decrease. RESULTS: Binary logistic regression analysis revealed that creatinine clearance level (Ccr) < 50 mL/min/1.73 m2 (OR, 5.463; 95% CI, 1.249-23.888, p = 0.024) and Cmin > 7 mg/L (OR, 62.660; 95% CI, 14.293-274.708, p = 0.001) were risk factors associated with linezolid-induced thrombocytopenia. Area under the ROC curve for Cmin was 0.955, with a maximum Youden index of 0.837. The corresponding critical value was 6.94 mg/L (sensitivity 91.5%; specificity 92.2%). Ccr < 50 mL/min/1.73 m2 (OR, 7.282; 95% CI, 1.765-30.048, p = 0.006) and Cmin > 7mg/L (OR, 6.364; 95% CI, 1.937-20.910, p = 0.020) were found to be associated with linezolid-induced hemoglobin reduction. The area under the ROC curve for Cmin was 0.755, Youden index was 0.477 at the maximum, and the corresponding critical value was 7.53 mg/L (sensitivity 77.8%; specificity 69.9%). CONCLUSIONS: Renal insufficiency is a related risk factor for linezolid-induced hematological toxicity. Patients receiving linezolid treatment should be closely monitored with blood routine and plasma concentration, particularly in patients with moderate or severe renal insufficiency. The plasma trough concentration of linezolid could be a suitable predictor for linezolid-induced thrombocytopenia and anemia.

Romiplostim in chemotherapy-induced thrombocytopenia: A review of the literature.

Chemotherapy-induced thrombocytopenia (CIT) is a common challenge of cancer therapy and can lead to chemotherapy dose reduction, delay, and/or discontinuation, affecting relative dose intensity, and possibly adversely impacting cancer care. Besides changing anticancer regimens, standard management of CIT has been limited to platelet transfusions and supportive care. Use of the thrombopoietin receptor agonist romiplostim, already approved for use in immune thrombocytopenia, has shown promising signs of efficacy in CIT. In a phase 2 prospective randomized study of solid tumor patients with platelet counts <100 × 109/L for ≥4 weeks due to CIT, weekly romiplostim corrected the platelet count to >100 × 109/L in 93% (14/15) of patients within 3 weeks versus 12.5% (1/8) of untreated patients (p < 0.001). Including patients treated with romiplostim in an additional single-arm cohort, 85% (44/52) of all romiplostim-treated patients responded with platelet count correction within 3 weeks. Several retrospective studies of CIT have also shown responses to weekly romiplostim, with the largest study finding that poor response to romiplostim was predicted by tumor invasion of the bone marrow (odds ratio, 0.029; 95% CI: 0.0046-0.18; p < 0.001), prior pelvic irradiation (odds ratio, 0.078; 95% CI: 0.0062-0.98; p = 0.048), and prior temozolomide treatment (odds ratio 0.24; 95% CI: 0.061-0.96; p = 0.043). Elsewhere, lower baseline TPO levels were predictive of romiplostim response (p = 0.036). No new safety signals have emerged from romiplostim CIT studies. Recent treatment guidelines, including those from the National Comprehensive Cancer Network, now support consideration of romiplostim use in CIT. Data are expected from two ongoing phase 3 romiplostim CIT trials.

Effective and safe use of intramuscular clozapine in a patient presenting with catatonia and thrombocytopenia.

Clozapine is the most effective medication for the management of treatment-resistant schizophrenia and schizoaffective disorder, and its discontinuation can pose significant challenges in treatment. We present a patient with a diagnosis of schizoaffective disorder who was stable on clozapine for a decade until discontinuation due to thrombocytopenia. She experienced a relapse of her illness, presenting with psychotic and catatonic features with poor oral intake and physical health complications requiring a lengthy admission to the hospital. There was a poor response to alternative antipsychotics and a full course of electroconvulsive therapy. Intramuscular (IM) clozapine was initiated due to catatonia and refusal to accept oral medications. After receiving 10 doses of IM clozapine, she started accepting oral clozapine and made a full recovery within a few weeks. The low platelet count was persistent, and a bone marrow biopsy showed results consistent with immune thrombocytopenia being the cause of that low platelet count.

Injuries and deaths following Covid-19 vaccination: The ethical and legal case for compensation.

In April 2024, in a class action suit for compensation to families of persons suffering injury or death after vaccination with AstraZeneca's (AZ) Covid-19 vaccine [1], the manufacturer admitted in a UK court that the Oxford-AZ Covid-19 vaccine could cause a rare and potentially fatal blood clotting disorder ("thrombosis with thrombocytopenia syndrome" or TTS, which when triggered by a vaccine is called "vaccine induced thrombocytopenia and thrombosis, or VITT) [2]. The AZ Covid-19 vaccine is a chimpanzee adenovirus vectored vaccine encoding the SARS-CoV2 spike protein (ChAdOx1-S) marketed under the names Covishield and Vaxzevria.

Liver-targeting chimeras as a potential modality for the treatment of liver diseases.

Liver diseases pose significant challenges to global public health. In the realm of drug discovery and development, overcoming 'on-target off-tissue' effects remains a substantial barrier for various diseases. In this study, we have pioneered a Liver-Targeting Chimera (LIVTAC) approach using a proteolysis-targeting chimera (PROTAC) molecule coupled to the liver-specific asialoglycoprotein receptor (ASGPR) through an innovative linker attachment strategy for the precise induction of target protein degradation within the liver. As a proof-of-concept study, we designed XZ1606, a mammalian bromodomain and extra-terminal domain (BET)-targeting LIVTAC agent, which not only demonstrated enduring tumor suppression (over 2 months) in combination with sorafenib but also an improved safety profile, notably ameliorating the incidence of thrombocytopenia, a common and severe on-target dose-limiting toxic effect associated with conventional BET inhibitors. These encouraging results highlight the potential of LIVTAC as a versatile platform for addressing a broad spectrum of liver diseases.

Anti-PF4 positivity and platelet activation after Ad26.COV2·S vaccination in Brazil.

INTRODUCTION: The Ad26.COV2·S (Janssen/Johnson & Johnson) COVID-19 vaccine, has been rarely associated with vaccine-induced immune thrombocytopenia and thrombosis (VITT). We investigated the prevalence of anti-PF4 antibody positivity, thrombocytopenia, D-dimer elevation, plasmatic thromboinflammatory markers, and platelet functional assays following Ad26.COV2·S vaccination in Rio de Janeiro, Brazil. METHODS: From July to September 2021, participants were assessed prior, 1, and 3 weeks post-vaccination. Platelet count and D-dimer were measured at each visit and anti-PF4 at week 3. A positive anti-PF4 prompted retrospective testing of the sample from week 0. Individuals with new thrombocytopenia or elevated D-dimer, positive anti-PF4, and 38 matched controls without laboratory abnormalities were evaluated for plasmatic p-selectin, tissue factor, and functional platelet activation assays. RESULTS: 630 individuals were included; 306 (48.57%) females, median age 28 years. Forty-two (6.67%) presented ≥1 laboratory abnormality in week 1 or 3. Five (0.79%) had thrombocytopenia, 31 (4.91%) elevated D-dimer, and 9 (1.57%) had positive anti-PF4 at week 3. Individuals with laboratory abnormalities and controls showed a slight increase in plasmatic p-selectin and tissue factor. Ten individuals with laboratory abnormalities yielded increased surface expression of p-selectin, and their ability to activate platelets in a FcγRIIa dependent manner was further evaluated. Two were partially inhibited by high concentrations of heparin and blockage of FcγRII with IV.3 antibody. Plasma obtained before vaccination produced similar results, suggesting a lack of association with vaccination. CONCLUSIONS: Vaccination with Ad26.COV2·S vaccine led to a very low frequency of low-titer positive anti-PF4 antibodies, elevation of D-dimer, and mild thrombocytopenia, with no associated clinically relevant increase in thromboinflammatory markers and platelet activation.

Heparin Induced Thrombocytopenia Testing.

This article provides a comprehensive overview of Heparin-Induced Thrombocytopenia (HIT) with an emphasis on laboratory testing and advantages of automation. HIT is a critical condition arising from heparin exposure, leading to a contradictory combination of thrombocytopenia with an increased thrombosis risk. The article discusses HIT's history, clinical presentation, laboratory diagnosis, and management strategies. It highlights the importance of interdisciplinary collaboration for effective diagnosis and treatment, underscoring advancements in technology and targeted therapies that are shaping future approaches to HIT management.

Safety of Antiplatelet Therapy in Noncardioembolic Ischemic Stroke With Thrombocytopenia: The CASE II Study.

BACKGROUND: There is scant evidence regarding the safety of antiplatelet therapy in acute ischemic stroke (AIS) patients with thrombocytopenia. Our study aims to address this concern by examining AIS patients with thrombocytopenia from a large database in real-world settings. METHODS AND RESULTS: We included patients with AIS with a platelet count <100×109/L who had complete records of antiplatelet drug use. Those requiring anticoagulation or having contraindications to antiplatelet therapy were excluded. Short-term safety outcomes were in-hospital bleeding events, while the long-term safety outcome was 1-year all-cause mortality. A good clinical outcome was defined as functional independence, indicated by a modified Rankin Scale score of 0 to 2 at discharge. Propensity score matched analyses were used. We screened 169 423 patients with AIS from 90 stroke centers in the CASE II register, ultimately enrolling 2808 noncardioembolic patients with thrombocytopenia. In the propensity score matched analyses, no significant difference was observed between the antiplatelet and nonantiplatelet groups in terms of intracranial hemorrhage (odds ratio=0.855 [95% CI, 0.284-5.478]; P=0.160) or gastrointestinal bleeding (odds ratio=2.034 [95% CI, 0.755-5.478]; P=0.160). Antiplatelet therapy was associated with improved functional outcomes at discharge (odds ratio=1.405 [95% CI, 1.028-1.920]; P=0.033), and showed a trend towards reducing 1-year mortality (odds ratio=0.395 [95% CI, 0.152-1.031]; P=0.058). CONCLUSIONS: The use of antiplatelet therapy lessened as platelet count decreased in patients with AIS with thrombocytopenia. However, our findings suggest that antiplatelet medications remain safe and effective for this population.

Association of Metal Cations with the Anti-PF4/Heparin Antibody Response in Heparin-Induced Thrombocytopenia.

Heparin-induced thrombocytopenia (HIT) is an antibody-mediated immune response against complexes of heparin and platelet factor 4 (PF4). The electrostatic interaction between heparin and PF4 is critical for the anti-PF4/heparin antibody response seen in HIT. The binding of metal cations to heparin induces conformational changes and charge neutralization of the heparin molecule, and cation-heparin binding can modulate the specificity and affinity for heparin-binding partners. However, the effects of metal cation binding to heparin in the context of anti-PF4/heparin antibody response have not been determined. Here, we utilized inductively coupled plasma mass spectrometry (ICP-MS) to quantify 16 metal cations in patient plasma and tested for correlation with anti-PF4/heparin IgG levels and platelet count after clinical suspicion of HIT in a cohort of heparin-treated patients. The average age of the cohort (n = 32) was 60.53 (SD = 14.31) years old, had a mean anti-PF4/heparin antibody optical density [OD405] of 0.93 (SD = 1.21) units, and was primarily female (n = 23). Patients with positive anti-PF4/heparin antibody test results (OD405 ≥ 0.5 units) were younger, had increased weight and BMI, and were more likely to have a positive serotonin release assay (SRA) result compared to antibody-negative patients. We observed statistical differences between antibody-positive and -negative groups for sodium and aluminum and significant correlations of anti-PF4/heparin antibody levels with sodium and silver. While differences in sodium concentrations were associated with antibody-positive status and correlated with antibody levels, no replication was performed. Additional studies are warranted to confirm our observed association, including in vitro binding studies and larger observational cohorts.

An autopsy case of pulmonary tumor thrombotic microangiopathy that developed during chemotherapy for salivary duct carcinoma of the parotid gland.

Pulmonary tumor thrombotic microangiopathy (PTTM) is a rapidly progressive cancer-related disease with a dismal clinical course. The patient in this report was a 43-year-old man with metastatic salivary duct carcinoma arising from the parotid gland. Combined androgen blockade therapy was administered started as first-line treatment, but failed after 5 months, followed by docetaxel plus carboplatin therapy as second-line treatment, which failed after 3 months. Genomic profiling revealed a BRAF V600E mutation, and combined BRAF and MEK inhibitor therapy was started as third-line treatment. The cancer remained stable during the first 10 months of third-line treatment, but treatment was subsequently discontinued due to the onset of symptoms of fatigue, myalgia and arthritis. Twenty days after the onset of these symptoms and interruption of third-line treatment, the patient was urgently admitted to hospital with respiratory distress and severe thrombocytopenia. CT images at the time of admission led our radiologist to the possibility of PTTM, but the patient died the day after admission and autopsy findings indicated that PTTM was the cause of death. This report describes a very informative case of PTTM with sequential imaging and detailed autopsy findings were available and provides a literature review.

Heparin-Induced Thrombocytopenia in Patients Suffering Cardiogenic Shock.

OBJECTIVES: Cardiogenic shock (CS) is associated with high mortality. Patients treated for CS mostly require heparin therapy, which may be associated with complications such as heparin-induced thrombocytopenia (HIT). HIT represents a serious condition associated with platelet decline and increased hypercoagulability and remains a poorly researched field in intensive care medicine. Primary purpose of this study was to: 1) determine HIT prevalence in CS, 2) assess the performance of common diagnostic tests for the workup of HIT, and 3) compare outcomes in CS patients with excluded and confirmed HIT. DESIGN: Retrospective dual-center study including adult patients 18 years old or older with diagnosed CS and suspected HIT from January 2010 to November 2022. SETTING: Cardiac ICU at the Ludwig-Maximilians University hospital in Munich and the university hospital of Bonn. PATIENTS AND INTERVENTIONS: In this retrospective analysis, adult patients with diagnosed CS and suspected HIT were included. Differences in baseline characteristics, mortality, neurologic and safety outcomes between patients with excluded and confirmed HIT were evaluated. MEASUREMENTS AND MAIN RESULTS: In cases of suspected HIT, positive screening antibodies were detected in 159 of 2808 patients (5.7%). HIT was confirmed via positive functional assay in 57 of 2808 patients, corresponding to a prevalence rate of 2.0%. The positive predictive value for anti-platelet factor 4/heparin screening antibodies was 35.8%. Total in-hospital mortality (58.8% vs. 57.9%; p > 0.999), 1-month mortality (47.1% vs. 43.9%; p = 0.781), and 12-month mortality (58.8% vs. 59.6%; p > 0.999) were similar between patients with excluded and confirmed HIT, respectively. Furthermore, no significant difference in neurologic outcome among survivors was found between groups (Cerebral Performance Category [CPC] score 1: 8.8% vs. 8.8%; p > 0.999 and CPC 2: 7.8% vs. 12.3%; p = 0.485). CONCLUSIONS: HIT was a rare complication in CS patients treated with unfractionated heparin and was not associated with increased mortality. Also, HIT confirmation was not associated with worse neurologic outcome in survivors. Future studies should aim at developing more precise, standardized, and cost-effective strategies to diagnose HIT and prevent complications.

Niraparib in Japanese patients with platinum-sensitive recurrent ovarian cancer: final results of a multicenter phase 2 study.

OBJECTIVE: This study evaluated the long-term safety and efficacy of niraparib in Japanese patients with platinum-sensitive recurrent ovarian cancer. METHODS: This was a follow-up analysis of a phase 2, multicenter, open-label, single-arm study in Japanese women with platinum-sensitive, relapsed ovarian cancer. Participants received niraparib (starting dose 300 mg) once daily in continuous 28-day cycles. The primary endpoint was the incidence of Grade 3 or 4 thrombocytopenia-related events (defined as the overall incidence of the MedDRA Preferred Terms "thrombocytopenia" and "platelet count decreased") occurring in the 30 days after initial administration of niraparib, and secondary endpoints included evaluation of treatment-emergent adverse events and progression-free survival. RESULTS: Nineteen patients (median age, 62 years; median body weight, 53.9 kg) were enrolled. As previously reported, the incidence of Grade 3 or 4 thrombocytopenia-related events during the first 30 days of treatment was 31.6%. At data cutoff, median (range) treatment exposure was 504.0 (56-1,054) days and mean ± standard deviation dose intensity was 154.4±77.5 mg/day. The most common treatment-emergent adverse events were nausea (n=14, 73.7%), decreased platelet count (n=12, 63.2%), decreased neutrophil count (n=11, 57.9%), anemia, vomiting, and decreased appetite (all n=9, 47.4%). One patient was diagnosed with treatment-related leukemia, which resulted in death. Median (95% confidence interval) progression-free survival was 18.0 (5.6-26.7) months. CONCLUSION: Overall, the safety profile of niraparib was considered manageable in this study population of Japanese patients with platinum-sensitive, relapsed ovarian cancer and was consistent with that observed in studies of non-Japanese patients. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03759587.

Flow cytometry vs conventional methods for the evaluation of anti-PF4/heparin antibodies: a single center study.

Aim: Heparin-induced thrombocytopenia (HIT) is a rare, life-threatening, immune-mediated adverse effect of heparin administration. This study compares frequently used laboratory assays in terms of their effectiveness in HIT diagnosis.Materials & methods: Fifty patients with suspected HIT were tested by gel immunoassay and solid phase PF4/heparin antibody ELISA. On positive results, platelet activation markers P-selectin and Annexin V were assayed using flow cytometry.Results: Thirty/50 patients were negative for both immunoassays. Flow cytometry was performed in the 20 immunoassay positive patients. Platelet activation was observed in 7/20 in the presence of low heparin concentration (0.2 IU/ml).Conclusion: The results are in accordance with the currently available literature and flow cytometry seems a promising alternative in HIT laboratory investigation.

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Whole Exome Sequencing in Vaccine-Induced Thrombotic Thrombocytopenia (VITT).

Background: In February 2021, a few cases of unusual, severe thrombotic events associated with thrombocytopenia reported after vaccination with ChAdOx1 nCoV-19 (Vaxzevria) or with Johnson & Johnson's Janssen vaccine raise concern about safety. The vaccine-induced thrombotic thrombocytopenia (VITT) has been related to the presence of platelet-activating antibodies directed against platelet Factor 4. Objectives: We investigated VITT subject genetic background by a high-throughput whole exome sequencing (WES) approach in order to investigate VITT genetic predisposition. Methods: Six consecutive patients (females of Caucasian origin with a mean age of 64 years) were referred to the Atherothrombotic Diseases Center (Department of Experimental and Clinical Medicine, Azienda Ospedaliero-Universitaria Careggi, Florence) with a diagnosis of definite VITT underwent WES analysis. WES analysis was performed on the Illumina NextSeq500 platform. Results:WES analysis revealed a total of 140,563 genetic variants. Due to VITT's rare occurrence, we focused attention on rare variants. The global analysis of all high-quality rare variants did not reveal a significant enrichment of mutated genes in biological/functional pathways common to patients analyzed. Afterwards, we focused on rare variants in genes associated with blood coagulation and fibrinolysis, platelet activation and aggregation, integrin-mediated signaling pathway, and inflammation with particular attention to those involved in vascular damage, as well as autoimmune thrombocytopenia. According to ACMG criteria, 47/194 (24.2%) rare variants were classified as uncertain significance variants (VUS), whereas the remaining were likely benign/benign. Conclusion: WES analysis identifies rare variants possibly favoring the prothrombotic state triggered by the exposure to the vaccine. Functional studies and/or extensions to a larger number of patients might allow a more comprehensive definition of these molecular pathways.

Thrombocytopenia following iron repletion with ferrous gluconate.

Immune thrombocytopenia (ITP) is an autoimmune disorder marked by low platelet counts that puts patients at risk for spontaneous bleeding. A rare trigger for ITP is iron repletion, which has only been reported in a few cases. In this article, we present a unique case of a 54-year-old male with a history of recurrent ITP who experienced rapid thrombocytopenia following iron repletion with ferrous gluconate. Discontinuation of ferrous medications resulted in platelet counts returning to the normal baseline. Following more than 30 years of the patient's clinical timeline, this case demonstrates the chronic nature of ITP and the complexity of its causes. Further studies are needed to determine the prevalence of iron repletion-induced thrombocytopenia and its underlying mechanisms.

Niraparib Population Pharmacokinetics and Exposure-Response Relationships in Patients With Newly Diagnosed Advanced Ovarian Cancer.

PURPOSE: Niraparib is a poly(adenosine diphosphate [ADP]-ribose) polymerase inhibitor approved for the maintenance treatment of advanced ovarian cancer (OC). Niraparib was originally approved in recurrent OC at a fixed starting dose (FSD) of 300 mg once daily (QD). This analysis characterized the population pharmacokinetics (PK) of niraparib and evaluated the relationships between exposure, efficacy, and safety to support clinical use of an individualized dosing strategy, in which the starting dose of niraparib was adjusted based on patient characteristics to improve the benefit-risk profile. METHODS: A population PK model was developed by pooling data from four niraparib clinical trials (PN001 [n = 104], QUADRA [n = 455], NOVA [n = 403], and PRIMA [n = 480]) in patients with solid tumors, including OC. Exposure-response analyses were conducted to explore the relationships of niraparib exposure with progression-free survival (PFS) and adverse events in the PRIMA study. A multivariate logistic regression model was also developed to estimate the probability of grade ≥3 thrombocytopenia, using data from patients enrolled in PRIMA and NOVA. The impact of an individualized starting dose (ISD) regimen (200 mg QD in patients with body weight [BW] <77 kg or platelet count [PLT] <150,000/µL, or 300 mg QD in patients with BW ≥77 kg and PLT ≥150,000/µL) on systemic exposure, efficacy, and safety was assessed. FINDINGS: Niraparib disposition was best described by a 3-compartment model with linear elimination. Key covariates included baseline creatinine clearance, BW, albumin, and age, all of which had minor effects on niraparib exposure. Comparable model-predicted exposure up to the time of disease progression/death or censoring in the 300-mg FSD and 200-/300-mg ISD groups was consistent with the lower rate of dose reduction in the ISD groups. No consistent niraparib exposure-response relationship was observed for efficacy in all PRIMA patients (first-line OC), and no statistically significant difference was seen in PFS curves for patients receiving a niraparib dose of 200 mg versus 300 mg. In the multivariate regression model, performed using combined data from PRIMA and NOVA, higher niraparib exposure (area under the concentration-time curve at steady-state [AUCss]), lower BW, and lower PLT were associated with an increased risk of grade ≥3 thrombocytopenia. IMPLICATIONS: Population PK and exposure-response analyses support use of an ISD to improve the safety profile of niraparib, including reducing the rate of grade ≥3 thrombocytopenia, without compromising efficacy. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, NCT01847274 (NOVA), NCT00749502 (PN001), NCT02655016 (PRIMA), NCT02354586 (QUADRA), www. CLINICALTRIALS: gov.

Heparin-induced thrombocytopenia with very high antibody titer is associated with slower platelet recovery and higher risk of thrombosis.

Heparin-induced thrombocytopenia (HIT) is a prothrombotic disorder mediated by platelet-activating antibodies targeting platelet factor 4 (PF4) and heparin complex. A higher antibody titer is reflected in a higher optical density (OD) by enzyme-linked immunosorbent assay for heparin-PF4 antibodies. This single-institution retrospective study of 116 HIT patients examined the effect of heparin-PF4 OD on time to platelet recovery, vascular thrombosis, and in-hospital mortality. Patients were divided into 3 cohorts based on heparin-PF4 OD: cohort 1 had an OD ≥ 2 and ≤ 2.4, cohort 2 had an OD > 2.4 and ≤ 2.8, and cohort 3 had an OD > 2.8. A higher OD titer was associated with significantly increased time to platelet recovery when compared between cohorts 1 versus 2 (HR = 0.599, p = 0.0221) and 1 versus 3 (HR = 0.515, p = 0.0014), as well as an increased risk of thrombosis (79.4%-cohort 3 vs 53.8%-cohort 2 vs 46.1%-cohort 1, p = 0.04), but had no impact on mortality (2.62-alive vs 2.65-deceased, p = 0.7432). A higher OD titer can inform risk assessment and support decision-making in HIT patients; however, prospective studies are needed to further clarify the impact of heparin-PF4 OD on outcomes.

Combination of 2 Quantitative Immunoassays and Clinical Score Algorithm to Reduce False-Negative Results in Heparin-Induced Thrombocytopenia: Prevalence Study of Mauriziano Hospital in Turin, Italy.

BACKGROUND: Heparin-induced thrombocytopenia (HIT) is a serious adverse effect of heparin treatment caused by platelet-activating anti-platelet factor 4 (PF4)/heparin antibodies. Accurate diagnosis of HIT is essential but remains challenging. The aim of our study was to explore the performance of our optimized diagnostic laboratory algorithm, based on Chemiluminescence (CliA) and ELISA immunoassays, on suspected HIT patients. The study compared the prevalence of HIT diagnosis in A.O. Mauriziano with the literature. METHODS: 163 consecutive patients were investigated for suspected HIT with CliA HemosIL Acustar HIT-IgG, Werfen. HIT was ruled out in all patients with CliA <0.13 U/mL. All patients with CliA >0.13 U/mL were further investigated with Zymutest-HIA anti-PF4 IgG ELISA immunoassay. In these patients, HIT was ruled out on the combination of CliA between 0.13 and 1.0 U/mL followed by ELISA assay <0.300 OD. HIT was ruled in patients whose plasma tested positive or doubtful with CliA and positive with ELISA immunoassay and confirmed positive with a platelet aggregation test (PAT). Suspicion of HIT was revealed with clinical 4Ts score or recent suggestive anamnestic history. RESULTS: Our diagnostic algorithm ruled out HIT diagnosis in 144/163 patients (88%) and predicted a positive PAT in 5/19 (26%) of CliA positive (4/5) or ELISA positive and CliA doubtful (1/5) patients. CONCLUSIONS: Our prevalence was 3.1%, comparable with the literature. The approach combining 2 quantitative immunoassays' (CliA and ELISA) results and 4Ts score probability was able to rule out the diagnosis within 1 h in 66% of patients with suspected HIT and within 24 h in 88% of patients. In the remaining 12% of cases, management decisions have to be based on individualized judgment while awaiting functional confirming results (48-72 h).

Heparin-Induced Thrombocytopenia After Revascularization of Gustilo-Anderson Type IIIC Open Lower Leg Fracture: A Case Report of Subsequent Ischemic Limb Salvage Failure.

BACKGROUND Heparin-induced thrombocytopenia (HIT) is a disease in which the immune response elicited by heparin results in a state of hypercoagulability and platelet activation, leading to thrombocytopenia and thromboembolism. Gustilo-Anderson type IIIC open fractures of the extremities are defined as open fractures presenting with arterial injuries that require repair and result in treatment challenges and complications. The diagnosis of HIT can be difficult in patients with severe trauma with consumptive thrombocytopenia associated with heavy bleeding and the use of heparin after vascular anastomosis. CASE REPORT A 48-year-old man was injured in a car accident, pinching his right lower leg and sustaining a Gustilo-Anderson type IIIc open fracture, for which he underwent emergency revascularization surgery. Heparin was administered continuously immediately after the surgery. On postoperative day 9, ischemic changes were observed in the right foot, and we performed suture re-anastomosis; however, the blood circulation in the right lower leg did not resume, and right lower leg amputation was performed due to ischemic necrosis with the onset of HIT. Postoperatively, the patient was switched to edoxaban after the recovery of his platelet count. Thereafter, the patient experienced no new thrombus occlusion or wound trouble, and was able to walk on a prosthetic leg and return to daily life. CONCLUSIONS It is important to consider the possibility of HIT as soon as thrombocytopenia appears in patients with Gustilo-Anderson type IIIC open fracture who are receiving heparin after vascular anastomosis, as a delayed diagnosis of HIT can make it difficult to save the limb.