Platelets Of Patients Research Articles

Transcription Factor RUNX1 Regulates Pctp (Phosphatidylcholine Transfer Protein) in Platelets: A Potential Role in Regulating Platelet Function

Transcription factor (TF) mutations are increasingly recognized to play a major role in inherited platelet abnormalities. RUNX1, a critical hematopoietic TF, acts in a combinatorial manner with other TFs to regulate numerous megakaryocyte (MK)/platelet genes. Human RUNX1 haplodeficiency is associated with thrombocytopenia, numerous platelet function defects, and increased leukemia risk. We have previously described a patient with a heterozygous RUNX1 nonsense mutation in the conserved runt domain necessary for DNA binding (Sun et al Blood 2004;103;948-54). The patient's platelet abnormalities included impaired aggregation and secretion in response to multiple agonists, granule deficiency, and decreased phosphorylation of myosin light chain and pleckstrin, activation of GPIIb-IIIa, 12-HETE production, and platelet protein kinase C-θ. Transcript expression profiling of patient platelets (Sun et al, J Thromb Haemost 2007;5:146-54) showed numerous genes were significantly downregulated, including myosin light chain (MYL9), platelet factor 4 (PF4), protein kinase C-θ (PRCKQ), and 12-lipoxygenase (ALOX12); these have been shown by us to be regulated by RUNX1. The profiling data also showed 10-fold downregulation of phosphatidylcholine transfer protein (PCTP) gene (fold change ratio 0.09, p=0.02) in the patient compared with normal controls. PCTP is a member of the START (Steroidogenic Acute Regulatory Protein-Related Transfer) domain superfamily and is responsible for the intermembrane transfer of phosphatidylcholine (PC), a major plasma membrane phospholipid. Several findings indicate that PCTP is important for platelet function. PC is the main fraction of platelet phospholipids and source of arachidonic acid (AA) upon activation. Release of free AA from PC is the rate-limiting step in thromboxane production. PC is also a substrate for phospholipase D, which yields phosphatidic acid that can generate the second messenger diacylglycerol. Importantly, platelet PCTP has recently been demonstrated to have a major role in the racial differences in platelet responses - increased PCTP expression has been linked to the higher platelet aggregation and calcium mobilization induced by thrombin receptor protease-activated receptor 4 (PAR4) in blacks as compared to whites (Edelstein et al Nat Med 2013;19:1609-16). Little is known regarding the regulation of PCTP in MKs/platelets.Based on the decreased platelet PCTP expression in our patient, we pursued the hypothesis that PCTP is regulated by RUNX1. Corrected total cellular immunofluorescence with anti-PCTP antibody showed significantly reduced platelet PCTP expression by 58% in our patient compared to a normal control. In silico analysis revealed 5 RUNX1 consensus binding sites up to 995 bp of the PCTP 5' upstream region from ATG. To assess for interaction of RUNX1 with the PCTP promoter, chromatin immunoprecipitation (ChIP) assay with anti-RUNX1 antibody was performed using human erythroid leukemia (HEL) cells treated with phorbol 12-myristate 13-acetate (PMA) for 24 hours to induce megakaryocytic transformation. The ChIP studies showed RUNX1 binding to PCTP chromatin in the regions encompassing RUNX1 binding sites 1 (-232/-227) and 2 (-345/-340), at site 3 (-519/-514), and encompassing sites 4 and 5 (-861/-856, -884/-879). Electrophoretic mobility shift assay (EMSA) using PMA-treated HEL cell nuclear extracts showed RUNX1 binding to DNA probes (28-37 bp) containing site 1 (-232/-227) and both sites 4 and 5 (-861/-856, -884/-879). To assess the effect of modulating RUNX1 expression on PCTP expression, PMA-treated HEL cells were transfected with RUNX1 overexpression plasmid or siRNA. PCTP mRNA and protein expression were increased with RUNX1 overexpression and reduced with RUNX1 knockdown, suggesting that PCTP is regulated by RUNX1.Conclusions: Our results provide evidence that PCTP is a direct transcriptional target of and regulated by RUNX1, and a cogent molecular mechanism for downregulation of platelet PCTP in our patient with RUNX1 haplodeficiency. Regulation of PCTP by RUNX1 may be relevant to the platelet dysfunction in RUNX1 haplodeficiency as well as to racial differences in platelet responses linked to the differential platelet expression of PCTP. DisclosuresNo relevant conflicts of interest to declare.

Acquired amegakaryocytic thrombocytopenic purpura induced by percutaneous ethanol injection during treatment of hepatocellular carcinoma: A case report.

Percutaneous ethanol injection is an important localized treatment method for patients presenting with hepatocellular carcinoma (HCC). Among the advantages of percutaneous ethanol injection are its minimal invasiveness, simplicity, low cost and low risk of complications. However, the increasing popularity of percutaneous ethanol injection has resulted in serious adverse effects attributed to individual variations. The present study describes the case of a patient who exhibited acquired amegakaryocytic thrombocytopenic purpura, caused by percutaneous ethanol injection treatment for HCC. This complication was promptly identified, and platelet transfusion and injection of recombinant human interleukin-11 resulted in a rapid recovery of the patient's platelet count. Attention should be given to this rare complication in patients administered percutaneous ethanol injection treatment for HCC.

Approach to managing platelet refractory patients

The diagnosis of platelet refractoriness is made when at least on two sequential occasions, a 10‐min to 1‐h post‐transfusion, the CCI is less than 5 × 109/l, using ABO‐identical fresh platelets of less than 72 h old. In practice, an increase in the patient's platelet counts of <10 × 109/l after the transfusion can be used. Refractoriness to platelet transfusion can be due to non‐immune and immune causes. Non‐immune causes include sepsis and disseminated intravascular coagulation. Twenty percent of cases have a combination of both immune and non‐immune causes. Immune causes include alloimmunization to human leukocyte antigen (HLA) and/or human platelet antigens(HPA). The pattern of refractoriness and clinical condition may assist in determining the cause. Patients who are likely to receive multiple platelet transfusion should have their post transfusion platelet count estimated. If refractoriness is suspected, HLA typing and antibody investigation should be done. While waiting for the test result and the supply of HLA matched platelets, ABO compatible platelets may be given. Doubling the dose or giving more frequent transfusion maybe necessary in non‐immune cases. Where patient's HLA type is known, an identical or closely identical platelet can be given. Another approach is by giving platelet from donors lacking HLA antigens that correspond to the recipient's alloantibodies. Crossmatched platelets can be given in the absence of typed HLA platelets. Approximately 20–25% cases may be due to platelet‐specific antibodies, and undetected HLA incompatibility, in which case, the patient can be given antigen negative platelet.

Case Report Serious pulmonary infection in a splenectomized patient with adult type 1 Gaucher disease.

A 49-year-old man with a history of Gaucher disease type 1, resulting in serious splenomegaly and eating disorder, was referred to our department and underwent a splenectomy under general anesthesia. Gaucher disease is very rare, and its first signs are unexplained splenomegaly and hypersplenism. On preoperative examination, the patient's platelet count was slightly low, and his other test results were normal. Surprisingly, on the first postoperative day, the patient developed a lung infection. This gradually progressed to acute respiratory distress syndrome with respiratory failure, requiring intubation and mechanical ventilation. The patient eventually recovered, and he was discharged after receiving antibiotics and other treatments to enhance immunity. However, his postoperative lung infection led to a significantly prolonged and expensive hospital stay. This case suggests that we must pay close attention to the immune dysfunction of patients with Gaucher disease type 1. Anesthesia and surgery with accompanying post-traumatic stress can weaken patients' immunity and cause susceptibility to severe lung infections. Pulmonary signs and functions should be monitored closely during the perioperative period, and, if necessary, gamma globulin and thymosin should be administered early in the preoperative or postoperative period to enhance immunity.

Retrospective analysis of the risk factors for linezolid-induced thrombocytopenia in adult Japanese patients.

Thrombocytopenia is a major side effect of linezolid therapy. However, there are few reports about the risk factors for linezolid-induced thrombocytopenia. The aim of this study is to evaluate the risk factors for thrombocytopenia in patients who undergo linezolid therapy. Aomori Prefectural Central Hospital in Japan, a tertiary 695 beds hospital. A retrospective review was performed using the hospital's medical records. From January 2010 to August 2012, 75 adult patients who received linezolid therapy were enrolled in this study. Linezolid-induced thrombocytopenia was defined as a decrease in the patient's platelet count to <10 × 10⁴/μL or a reduction of ≥30 % from their baseline value. Odds ratios (OR) for thrombocytopenia were analyzed using multivariate stepwise logistic regression analysis. Thrombocytopenia occurred in 29 patients (38.6 %), seven of whom required platelet transfusions. The patients who developed thrombocytopenia were significantly older, displayed a significantly higher frequency of renal insufficiency, and received linezolid therapy for significantly longer than the patients without thrombocytopenia. Stepwise logistic regression analysis suggested that receiving linezolid therapy for ≥14 days was a significant risk factor for thrombocytopenia [OR 13.3, 95 % confidence interval (CI) 3.2-55.6, p < 0.01], whereas the creatinine clearance rate exhibited a significant negative correlation with the incidence of the condition [OR 0.98, 95 % CI 0.96-0.99, p = 0.037]. The incidence of thrombocytopenia among the patients who demonstrated creatinine clearance rates of <30 mL/min was 60 % (12/20), which was significantly higher than that observed among the patients who displayed creatinine clearance rates of more than 60 mL/min (26.4 %, 9/34, p = 0.014). Receiving linezolid therapy for ≥14 days and a low creatinine clearance rate were suggested to be risk factors for linezolid-induced thrombocytopenia. The platelet counts of patients with these risk factors should be closely monitored.

Development of model for analysing respective collections of intended hematopoietic stem cells and harvests of unintended mature cells in apheresis for autologous hematopoietic stem cell collection

Hematopoietic stem cells (HSCs) required to perform peripheral hematopoietic autologous stem cell transplantation (APBSCT) can be collected by processing several blood volumes (BVs) in leukapheresis sessions. However, this may cause granulocyte harvest in graft and decrease in patient's platelet blood level. Both consequences may induce disturbances in patient. One apheresis team's current purpose is to improve HSC collection by increasing HSC collection and prevent increase in granulocyte and platelet harvests. Before improving HSC collection it seemed important to know more about the way to harvest these types of cells. The purpose of our study was to develop a simple model for analysing respective collections of intended CD34+ cells among HSC (designated here as HSC) and harvests of unintended platelets or granulocytes among mature cells (designated here as mature cells) considering the number of BVs processed and factors likely to influence cell collection or harvest. For this, we processed 1, 2 and 3 BVs in 59 leukapheresis sessions and analysed corresponding collections and harvests with a referent device (COBE Spectra). First we analysed the amounts of HSC collected and mature cells harvested and second the evolution of the respective shares of HSC and mature cells collected or harvested throughout the BV processes. HSC collections and mature cell harvests increased globally (p<0.0001) and their respective shares remained stable throughout the BV processes (p non-significant). We analysed the role of intrinsic (patient's features) and extrinsic (features before starting leukapheresis sessions) factors in collections and harvests, which showed that only pre-leukapheresis blood levels (CD34+cells and platelets) influenced both cell collections and harvests (CD34+cells and platelets) (p<0.001) and shares of HSC collections and mature unintended cells harvests (p<0.001) throughout the BV processes. Altogether, our results suggested that the main factors likely to influence intended HSC collections or unintended mature cell harvests were pre-leukapheresis blood cell levels. Our model was meant to assist apheresis teams in analysing shares of HSC collected and mature cells harvested with new devices or with new types of HSC mobilization.

Simultaneous presentation of JAK2 V617F mutation-related essential thrombocythemia and B-cell chronic lymphocytic leukemia.

Simultaneous presentation of JAK2 V617F mutation-related essential thrombocythemia and B-cell chronic lymphocytic leukemia.

Platelet count control in immune thrombocytopenic purpura patient: optimum romiplostim dose profile

Patients with immune thrombocytopenic purpura (ITP), a disease characterized by abnormally low platelet count, are susceptible to excessive bleeding as a direct consequence. While the problem of low platelet count can be addressed fundamentally either by slowing down the rate of platelet destruction or by increasing platelet production, or both, one of the more effective means of treating ITP patients is to increase platelet production with romiplostim. However, current romiplostim treatment strategies tend to produce undesirable responses where platelet counts oscillate between dangerously low values and extremely high peaks, as a direct consequence of the complex nonlinear dynamics associated with platelet count regulation. The objective of this study is to determine the optimum dose profile of romiplostim for a specific ITP patient required to maintain a platelet count of 70×109/L. Using clinical data of the specific patient's platelet count obtained in response to a series of subcutaneously applied doses of romiplostim, a standard pharmacokinetics/pharmacodynamics (PKPD) model was developed, validated, and analyzed to obtain insight into the patient's physiological characteristics. The model was subsequently used to investigate the performance of three control strategies: “fixed dose” open-loop control, “variable dose” discrete PI feedback control, and “variable dose” model-based open-loop optimal control. The control strategies were implemented for weekly and bi-weekly treatment regimens. With both treatment frequencies, the fixed dose open-loop control strategy resulted in unacceptable sustained oscillating platelet count. PI feedback control and model-based optimal open-loop control led to stable platelet count profiles after approximately 50 days but only for weekly injections. In summary, a stable platelet count is more likely to be achieved consistently in the specific patient with weekly treatments. Bi-weekly treatments are less effective because, as we show, fundamental pharmaceutical characteristics of romiplostim make oscillations in platelet count unavoidable at this treatment frequency. The results show that model-based decisions determined using patient-specific mathematical models are potentially useful for designing better treatment regimens for ITP patients.

Sustained Response After Short-Medium-Term Treatment With Eltrombopag In Patients With ITP

IntroductionEltrombopag is an oral, non-peptide thrombopoietic receptor-agonist (TPO-RA).In chronic immune thrombocytopenic purpura (ITP) randomized–controlled trials proved to be effective, safe and well tolerated with reported response rates of 59%-88%.When eltrombopag is discontinued, platelet counts usually return to baseline within 2 weeks. However, certain patients may be able to discontinue TPO-RA and still maintain platelet counts above baseline without additional treatment.We report here 12 patients who presented sustained responses after discontinuing eltrombopag without substituting additional anti-ITP therapy. Patients and MethodsPrimary ITP was defined as a platelet count < 100 x 109/L in the absence of other causes or disorders that may be associated with thrombocytopenia.Patients received daily oral eltrombopag, at a starting dose of 50 mg/day adjusting the dose as needed up to a maximum of 75 mg/day based on the patient's platelet count.Successful discontinuation of eltrombopag treatment was defined as a platelet count of 30,000/μl and 20,000/μl above initial baseline for at least 6 months off eltrombopag without substituting additional anti-ITP therapy. ResultsOur patients were 4 males and 8 females, with a mean disease onset age of 55 years (range, 28–79 years). The median time from diagnosis to eltrombopag start was 24 months (range, 1-480). 5 cases had ITP since less than 1 year.The median prior number of therapies was 5 (range, 1-7). All patients were refractory to corticosteroids. Six patients had received rituximab: Patient (P) 1, P2, P3, P6, P7 and P8. Seven patients were splenectomized.Three patients (P2, P6 and P8) who failed to respond to romiplostim were switched to eltrombopag. One romiplostim responder (P12) switched to eltrombopag because patient request. The median platelet count before starting treatment was 7 x 109/L (range, 1-97 x 109/l).At start, concomitant treatment was administered in 4 patients: P2, P3 and P9 corticosteroids. P5, intravenous immunoglobulin.The median maximum platelet count during treatment was 482 x109/l (range, 251-858 x109/l). One patient had a transient increase in leukocyte count reaching 12x109/L.The median duration of treatment was 5 months (range, 1-13) (Fig 1A): only one month in three patients. Nine patients stopped treatment due to platelets higher than 250 x 109/l. [Display omitted] Initial stop of eltrombopag in P2 was failed because of low platelet counts and eltrombopag was reinitiated. After 8 months of re-treatment, eltrombopag could be stopped with no other treatments needed for over 6 months.In P1, P10 and P11 eltrombopag was stopped at 140, 178 and 138 x109/L platelets, respectively. After a median follow-up of 7 months (range, 6 – 20 months), ten patients maintain a platelet count greater than 100 x 109/L (Fig 1B) without any anti-ITP treatment. [Display omitted] DiscussionThe possibility of eltrombopag cessation in a specific subset of patients has emerged.Recently, a prospective ongoing study has demonstrated that approximately 1/3 of patients (5 of 15) appear able to successful elective discontinuation of eltrombopag after 2 or more years of treatment.Nevertheless we have showed that the remission of ITP is feasible after short term treatment with eltrombopag (3 patients treated for only 1 month).Repeated short-term use of eltrombopag in chronic ITP has been reported. Patient P2 could succesfully reintroduce eltrombopag after initial treatment stop.In our data no factors predict which patients may discontinue eltrombopag.Table 1Summary of 12 ITP patients with successful discontinuation of eltrombopagP1P2P3P4P5P6P7P8P9P10P11P12Median (range)Years64285971465161794050664555 (28-79)Gender (M/F)FFFFFMMFMFMF-Prior lines therapies for ITP4677555621125 (1-7)Splenectomy (yes/no)YYYYNYYYNNNN-ITP duration before TPO-RA (months)133991084735216480112324 (1-480)Platelet count before TPO-RA (x109/L)1051222935221250977 (1 - 97)Maximum doses of TPO-RA (mg/day)50255075505050505075505050 (25-75)Maximum platelet count during TPO-RA treatment (x109/L)413600800354416255548392550251858580482 (251-858)Duration of TPO-RA (months)131214591315255 (1-13)Side effect of TPO-RANoneYNoneNoneNoneNoneNoneNoneNoneNoneNoneNone-Months after cessation of TPO-RA76208716151876767 (6-20)Platelet count, last visit (x109/L)3103104384023383403682082087629044310 (44-438) Disclosures:San Miguel:Jansen, Celgene Corporation, Onyx, Novartis, Millenium: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees.

Severe Acquired Bleeding Tendency Secondary To An Anti-Thrombin Antibody In a Patient With Monoclonal Gammapathy Of Unknown Significance: Direct In Vivo evidence

IntroductionAnti-thrombin antibodies are a rare cause of acquired bleeding disorder. We report a case of a patient with a monoclonal gammapathy of unknown significance (MGUS) referred to us for an acquired bleeding tendency. We found that he had an isolated anti-thrombin antibody and showed that this antibody inhibit platelet accumulation and fibrin generation in vivo in a mouse model of arterial thrombus formation. PatientA 40-year-old man with no personal or familial history of bleeding was referred to us for multiple bleeding episodes (rectal bleeding, hematoma) for 18 years. He was diagnosed 12 years previously with an IgG Kappa MGUS which was stable. Complete blood counts were normal. Activated partial thromboplastin time (APTT) and thrombin time (TT) were prolonged at 76 seconds (control 35) and > 120 seconds (control 18) respectively. The prolonged TT was observed using human and bovine thrombin. A TT mixing study was performed by measuring the TT of serial dilutions of patient's plasma in normal pooled plasma. This study confirmed an acquired anti-thrombin activity of patient's plasma, as TT of the mix was prolonged from dilutions 1:1 to 1:16 (>120 to 25 seconds). Other coagulation factors were normal. No other auto-antibodies were detected except an isolated lupus anticoagulant. Thrombin generation in patient's platelet rich plasma measured using the Calibrated Automated Thrombogram (CAT) showed a prolonged lag time (15.5 versus 4.7 minutes) associated with a decreased endogenous thrombin potential (ETP, 834 versus 1730 nmol/L min). The diagnosis of an acquired anti-thrombin antibody associated with a MGUS was proposed. The patient received multiple treatments, including immunosuppressive agents, anti-CD20 monoclonal antibody therapy and bortezomib, in order to eradicate the antibody with no success. MethodsAnti-thrombin IgG antibodies were affinity purified from the patient's plasma using activated agarose beads covalently coupled to human alpha thrombin (Aminolink, ThermoScientific). A mouse model of thrombosis was used to test the effect of the infusion of the purified anti-thrombin IgG on thrombus formation in vivo. Platelet accumulation and fibrin generation at the site of injury was imaged after laser-induced injury of cremaster arterioles using intravital microscopy in wild type mice. Platelet and fibrin labeling were performed using anti-CD42 antibody conjugated to DyLight 488 (Emfret) and an anti-fibrin antibody conjugated with AlexaFluor 647 (Sekisui). ResultsImmunoblotting using human and bovine alpha-thrombin thrombin confirmed the purified IgG from the patient's plasma (yield 86 µg/ml) to be anti-thrombin antibodies. At a concentration of 2.45 mg/mL, these anti-thrombin IgG were able to prolong APTT and TT (59 versus 33 seconds and >120 versus 19 seconds, respectively). Control IgG (2.5 mg/mL) purified from healthy individuals had no effect on APTT and TT. Using the mouse model of laser-induced arteriolar injury, we found that patient-derived anti-thrombin IgG (690 microg) caused a significant inhibition of platelet accumulation and fibrin generation of more than 70% at the site of vessel wall injury. ConclusionWe report a case of severe acquired bleeding tendency secondary to an anti-thrombin antibody in a patient with an IgG Kappa MGUS. Anti-thrombin IgG antibodies purified from the patient's plasma retain the anti-thrombin activity in vitro. Additionally, infusion of purified anti-thrombin IgG from the patient induced a dramatic decrease in platelet thrombus accumulation and fibrin generation at the site of injury in a mouse model of arterial injury, proving the etiology of patient's bleeding tendency. This is the first description of the anti-thrombotic effect of anti-thrombin antibodies directly in vivo. Disclosures:Turhan:BMS, Novartis: Honoraria, Research Funding.

Meloxicam‐Induced Thrombocytopenia

Immune thrombocytopenia can have several causes including the use of certain drugs. Thrombocytopenia has been documented as a rare adverse effect of some nonsteroidal antiinflammatory drugs (NSAIDs) including diclofenac, naproxen, and ibuprofen. However, only one previously documented case of meloxicam-associated thrombocytopenia has been reported in the literature. We describe an 84-year-old woman who developed a case of immune-mediated thrombocytopenia that was attributed to meloxicam therapy. The patient's platelet count decreased from a baseline of 267×10(3) /mm(3) to 2×10(3) /mm(3) 1week after she received her first lifetime dose of meloxicam. She also experienced black stools and bruising that coincided with the meloxicam administration. The almost immediate onset of thrombocytopenia and symptoms after initiation of meloxicam, as well as the marked reduction in her platelet count, suggest an idiosyncratic reaction. According to the Hill criteria for assessing causality of adverse drug events, it is plausible that this reaction was due to meloxicam. Health care providers should be aware of the possibility of thrombocytopenia secondary to NSAID therapy including meloxicam. Immune thrombocytopenia can be life threatening if it is not identified and treated promptly. A thorough medication history is particularly important when patients present with unusual symptoms, with a focus on those drugs that have been recently initiated. Although thrombocytopenia is a rare adverse effect of NSAID therapy, it should be considered a potential cause in patients receiving these drugs who have signs and symptoms consistent with this blood dyscrasia.

A case of pseudohyperkalaemia secondary to thrombocytosis in a patient with grumbling abdominal sepsis

A case of pseudohyperkalaemia secondary to thrombocytosis in a patient with grumbling abdominal sepsis

A 3-Year-Old Girl with Frequent Nose Bleeds

A 3-year-old girl presented with petechial hemorrhages and repeated nosebleeds. Two weeks earlier she had been admitted to a local hospital with nosebleeds accompanied by 2 episodes of vomiting dark red blood. Results of the laboratory evaluation included: white blood cell count, 8.2 × 109/L [reference interval (RI),3 4 × 109/L to 10 × 109/L]; hemoglobin, 10.7 g/dL (RI, 11–15 g/dL); platelet count, 142 × 109/L (RI, 100 × 109/L to 300 × 109/L), prothrombin time, 11.5 s (RI, 9–13 s); activated partial thromboplastin time, 31.2 s (RI, 26–39 s); and fibrinogen, 2.5 g/L (RI, 2.0–4.0 g/L). The patient was discharged in good condition after insertion of nasal packs. One day before the current admission, the patient had nose bleeds once again, this time accompanied by 4 episodes of hematemesis and tarry stool. At presentation, she had no fever and no diarrhea. She was not on any medications. The patient had a history of easy bruising, repeated gum bleeding, but not hemarthrosis. There was no family history of abnormal bleeding. On examination, she appeared pale, with normal vital signs. Her skin had scattered petechiae. The physical examination was otherwise unremarkable. At presentation, laboratory findings included the following: hemoglobin, 6.2 g/dL (RI, 11–15 g/dL); reticulocyte count, 6.8% (RI, 0.5%–1.5%). Other laboratory results are shown in Table 1. View this table: Table 1. Patient's laboratory results. In vitro testing showed that the patient's platelets did not aggregate in response to ADP, epinephrine, arachidonic acid, or collagen, but platelets had relatively normal ristocetin-induced aggregation. These findings were confirmed on repeat testing. A smear of peripheral blood showed no clusters of normal platelets. A flow cytometry evaluation revealed marked reduction in glycoprotein IIb/IIIa (GPIIb/IIIa). ### QUESTIONS TO CONSIDER 1. What disorders should be considered in the workup of children with repeated nose bleeds? …

A 7‐Year Case of Furosemide‐Induced Immune Thrombocytopenia

Immune thrombocytopenia has been attributed to many causes. Several drugs have been implicated as culprits in causing drug-induced thrombocytopenia. Although the mechanism for this type of thrombocytopenia is not well understood, at least three types of antibodies appear to be involved: drug-dependent antibodies, hapten-dependent antibodies, and drug-induced platelet-reactive autoantibodies. In this report, we describe a case in which furosemide was identified as the probable cause of drug-induced thrombocytopenia in an 84-year-old man with chronic symptomatic idiopathic thrombocytopenia for seven years before discovery. The patient's platelet count and daily furosemide dose, both intravenous and oral, were documented throughout his medical history. A dose-dependent change in platelet count was observed in association with the furosemide dose. His platelet count increased on discontinuation of furosemide and beginning of torsemide. Several months after discontinuation of furosemide, his platelet count increased to a 9-year high of 206 × 10³/mm³ from a low of 36 × 10³/mm³ while receiving furosemide therapy. Based on the observations of this case report, clinicians should more readily consider furosemide as a potential cause of thrombocytopenia.

Probable carvedilol-induced thrombocytopenia

A case of probable carvedilol-induced thrombocytopenia is reported. A 64-year-old African-American woman with a history of hypertension, diastolic dysfunction, mild left-ventricular hypertrophy, and pulmonary embolism was hospitalized with a platelet count of 94,000 platelets/mm(3). Dalteparin, warfarin, and carvedilol had recently been added to her medication regimen. Beta-2-glycoprotein immunoglobulin G (IgG) antibody, anticardiolipin IgG, and anticardiolipin immunoglobulin M tests, conducted to rule out antiphospholipid syndrome, revealed values within the normal range. After the exclusion of dalteparin, hydrochlorothiazide, and other causes of drug- and non-drug-related thrombocytopenia, carvedilol was discontinued and replaced with metoprolol tartrate. After this substitution, the patient's platelet count continued to rise. On hospital day 10, the patient was discharged to home on low-molecular-weight heparin bridging therapy, warfarin sodium 5 mg orally daily, ranitidine 150 mg orally daily, metoprolol tartrate 75 mg orally twice daily, lisinopril 20 mg orally daily, amlodipine 10 mg orally daily, cyanocobalamin 1000 mg orally daily, and two tablets of hydrochlorothiazide 25 mg-triamterene 37.5 mg orally daily. Her platelet count was 319,000 platelets/mm(3) on the day of discharge and remained stable thereafter. The recovery time of the platelets coincided with the elimination half-life of carvedilol. A woman developed thrombocytopenia, first noticed as a reduction in the platelet count to a low-normal value, 17 days after treatment with carvedilol was begun. Other possible culprit drugs were withdrawn, but the platelet count continued to drop until carvedilol was discontinued. The platelet count rose on the day of carvedilol removal and was within the normal range within another day.

Platelet count predicts prognosis in operable non-small cell lung cancer

Platelets play a significant role in cancer cell growth, progression and metastasis. However, in non-small cell lung cancer (NSCLC), the association between a patient’s platelet count and prognosis has not previously been fully elucidated. The aim of the present study was to investigate the correlation between platelet count, patients’ characteristics and prognosis in patients with NSCLC. A total of 510 NSCLC patients were enrolled in the present study. The median platelet count in the NSCLC patients was 203×109/l (95% CI, 115–358×109/l). The median platelet count in T3 and T4 patients was significantly higher than that of T1 and T2 patients (median, 263×109/l and 253.5×109/l vs. 199.5×109/l and 196.5×109/l, respectively; P<0.001). The 3-year cumulative overall survival (OS) probability was 75.3% for patients with normal platelet counts and 59.2% for patients with elevated platelet counts. When compared with the patients with normal platelet counts, the patients with elevated platelet counts had an increased risk of disease progression (HR, 1.568; 95% CI, 1.015–2.453). Pre-operative platelet counts are a novel independent prognostic biomarker in operable NSCLC.

CORRELATION BETWEEN RESPONSE TO PRASUGREL AND LEVELS OF RETICULATED PLATELETS IN PATIENTS WITH STEMI

CORRELATION BETWEEN RESPONSE TO PRASUGREL AND LEVELS OF RETICULATED PLATELETS IN PATIENTS WITH STEMI

Incidence of drug-induced thrombocytopenia in hospitalized patients

To find out the incidence of drug-induced thrombocytopenia and which medications are implicated, and to establish pharmaceutical activity for its prevention and resolution. A prospective study was conducted between June and December 2009 in hospitalized patients over 18 years of age with thrombocytopenia. The medications considered to be associated with thrombocytopenia were included in a database drawn up from the bibliography. In a suspected case, the doctor was recommended to discontinue, decrease the dosage or keep the drug under observation; and a follow-up of the patient's platelet count was made in order to classify the relationship between the drug and thrombocytopenia. 273 patients were included (61.5% men) with a mean age of 60 ± 15 years. Mean stay was 18 ± 17 days. TCP incidence was 2.26%. The services most involved were Haematology (56), Intensive Care Medicine (48) and Oncology (40). TCP was moderate in 69% of cases, mild in 26 % and severe in 5%. There were 8 cases of drug-induced thrombocytopenia (0.063% incidence), which were resolved in an average of 7.6 days. The medications related were enoxaparin (2), linezolid (2), tacrolimus (2), thymoglobulin (1) and heparin (1). The doctor was recommended to discontinue the drug (2), decrease the dosage (3) or keep it under observation (3), with 100% acceptance. Pharmaceutical validation must incorporate an assessment of the platelet count, as it may contribute both to early identification of thrombocytopenia, and to following up platelet counts in patients receiving therapy with thrombocytopenia related drugs.

Thrombocytopenia and bleeding in pediatric oncology patients

Abstract Prophylactic platelet transfusions are the standard of care for patients with hypoproliferative thrombocytopenia after receiving chemotherapy or radiation for the treatment of malignancy, for BM replacement by leukemia or solid tumor, or in preparation for a hematopoietic stem cell transplantation.1 During this time of thrombocytopenia, these patients may receive both prophylactic platelet transfusions, which are given to prevent potentially life-threatening bleeding when a patient's platelet count drops below a predetermined threshold, and therapeutic platelet transfusions, which are given to treat active or recurrent bleeding. In the 1950s, the invention of the plastic blood bag allowed for the production and storage of platelet concentrates,2 and in the 1960s, it was recognized that prophylactic platelet transfusions effectively reduced hemorrhagic death in patients with newly diagnosed leukemia.3,4 In 1962, Gaydos published the paper that is frequently credited with the inception of the 20 000/μL platelet transfusion threshold.5 Despite a half-century of experience with prophylactic platelet transfusions, there are still insufficient data to provide clinicians with evidence-based guidelines specific to pediatric oncology and hematopoietic stem cell transplantation (HSCT) patients.

Novel mutation in Hermansky–Pudlak syndrome type 2 with mild immunological phenotype

Patients with Hermansky–Pudlak syndrome type 2 (HPS2) present with oculocutaneous albinism, nystagmus, prolonged bleeding time, and increased susceptibility to infections. Twelve HPS2 patients with mutations in the β3A-subunit of the cytosolic adaptor-related protein complex 3 (AP3B1, also called HPS2) have been described so far. Here, we report on a patient with oculocutaneous albinism who developed a life-threatening bleeding after tonsillectomy. She presented with moderate neutropenia and reduced granulopoiesis. Analyzing patient's impaired platelet function using electron microscopy and flow cytometry led to the diagnosis of HPS2. Flow cytometric analysis of the patient's platelets showed already elevated CD63 expression on resting platelets with no further increase after thrombin stimulation. Natural killer (NK) cell degranulation was partially impaired but target cell lysis of NK cells and cytotoxic T-lymphocytes (CTLs) were normal and the patient did not develop signs of hemophagocytic syndrome. Molecular genetic analyses revealed a novel 2 bp-deletion (c.3222_3223delTG) in the last exon of AP3B1 causing a frameshift and a prolonged altered protein. The location of the deletion at the very C-terminal end may prevent a complete loss of the HPS2 protein leading to a less pronounced severity of immunodeficiency than in other HPS2 patients.