Qualitative Platelet Dysfunction Research Articles

Thrombocytopenia and liver disease: pathophysiology and periprocedural management

Abnormal bleeding in patients with liver disease may result from elevated portal pressure and varix formation, reduced hepatic synthesis of coagulation proteins, qualitative platelet dysfunction, and/or thrombocytopenia. Major mechanisms of thrombocytopenia in liver disease include splenic sequestration and impaired platelet production due to reduced thrombopoietin production. Alcohol and certain viruses may induce marrow suppression. Immune thrombocytopenia (ITP) may co-occur in patients with liver disease, particularly those with autoimmune liver disease or chronic hepatitis C. Drugs used for the treatment of liver disease or its complications, such as interferon, immunosuppressants, and antibiotics, may cause thrombocytopenia. Periprocedural management of thrombocytopenia of liver disease depends on both individual patient characteristics and the bleeding risk of the procedure. Patients with a platelet count higher than or equal to 50 000/µL and those requiring low-risk procedures rarely require platelet-directed therapy. For those with a platelet count below 50 000/µL who require a high-risk procedure, platelet-directed therapy should be considered, especially if the patient has other risk factors for bleeding, such as abnormal bleeding with past hemostatic challenges. We often target a platelet count higher than or equal to 50 000/µL in such patients. If the procedure is elective, we prefer treatment with a thrombopoietin receptor agonist; if it is urgent, we use platelet transfusion. In high-risk patients who have an inadequate response to or are otherwise unable to receive these therapies, other strategies may be considered, such as a trial of empiric ITP therapy, spleen-directed therapy, or transjugular intrahepatic portosystemic shunt placement.

Spontaneous scapular region hematoma extending upto anterior chest wall in a patient of chronic myeloid leukaemia: an unusual site presentation

Spontaneous haemorrhage and thrombosis should always raise the suspicion of CML as one of the differential as it is associated with qualitative platelet dysfunction. We here report a rare case of CML with spontaneous hematoma at an unusual site. A 26 years male presented with complaints of sudden onset non traumatic spontaneous swelling over the left scapular region and progressively extending up-to the left anterior chest wall which was associated with dull aching moderate intensity pain. Swelling was warm, soft in consistency and tender. He also had hepato-splenomegaly. General blood picture showed marked leucocytosis with myeloid hyperplasia. CT scan thorax reported a large hypodense lesion in the scapular and anterior chest wall region which on diagnostic aspiration revealed blood thereby confirming the diagnosis of spontaneous hematoma with CML. Imatinib therapy was started and hematoma was managed conservatively with antibiotics. The swelling resolved spontaneously without any surgical intervention.

RASopathies and hemostatic abnormalities: key role of platelet dysfunction

BackgroundBleeding anomalies have been reported in patients affected by Noonan syndrome. No study has been performed in patients with molecularly confirmed RASopathy. We aimed to characterize the frequency and types of bleeding disorders in patients with RASopathies and evaluate any significant association with laboratory findings.Patients and methodsForty-nine individuals (PTPN11, n = 27; SOS1, n = 7; RIT1, n = 3; SPRED1, n = 1; LZTR1, N = 3; RAF1, n = 2; BRAF, n = 4; MEK1, n = 1; MEK2, n = 1), and 49 age- and sex-matched controls were enrolled. The “Paediatric Bleeding Questionnaire Scoring Key” was administered to patients and families. Laboratory screening tests including clotting factors dosing, platelet count, Prothrombin Time and Partial Thromboplastin Time, were employed both in patients and controls to characterize the bleeding diathesis. A subgroup of 29/49 patients and 29/49 controls was also tested for platelet function.ResultsRegardless of the gene involved, pathological paediatric bleeding scores were recorded in 14/49 (28.5%) patients. Indeed, 7 were mutated in PTPN11, 3 in SOS1, 2 in RIT1, 1 in BRAF, and 1 in MEK1. Compared to patients with normal bleeding scores, those with pathologic bleeding score showed higher prevalence of splenomegaly (p = 0.006), prolonged aPTT (p = 0.04), lower levels of coagulation factor V (FV, p = 0.001), FVII (p = 0.003), FX (p = 0.0008) and FXIII (p = 0.002), higher vWAg (p = 0.04), and lower platelet sensitivity to Ristocetin (p = 0.001), arachidonic acid (AA) (p = 0.009) and collagen (p = 0.01). The presence of hematomas inversely correlated with factor V (p = 0.002), factor VII (p = 0.003), factor X (p = 0.002) and factor XIII (p = 0.004) levels, and directly correlated with platelet response to collagen (p = 0.02) and AA (p = 0.01). The presence of splenomegaly directly correlated with the presence of hematoma (p = 0.006), platelet response to Ristocetin (p = 0.04) and AA (p = 0.04), and inversely correlated with factor V levels (p = 0.03).ConclusionsPatients with RASopathies and a bleeding tendency exhibit multiple laboratory abnormalities, including platelet-related disorders. Splenomegaly is frequently detected and might be a suggestive sign for qualitative platelet dysfunction. A comprehensive clinical assessment should be carried out at diagnosis, during the follow-up and before any surgical procedures. Since there is currently no consensus on management of bleeding complications, it is important that physicians closely monitor these patients.

Platelet Count and Function during Pediatric Extracorporeal Membrane Oxygenation.

Extracorporeal membrane oxygenation (ECMO) is a form of life support used to treat neonates, children, and adults with cardiorespiratory failure refractory to conventional therapy. This therapy requires the use of anticoagulation to prevent clotting in the extracorporeal circuit, but anticoagulation also increases the risk of bleeding on ECMO. Both bleeding and thrombosis remain significant complications on ECMO and balancing these risks is challenging. Acquired platelet dysfunction is common during ECMO and quantitative and qualitative platelet dysfunction contributes to bleeding risk. Optimal platelet count, function, and transfusion thresholds are not well established during pediatric ECMO. In this review, we provide an overview of hemostatic alterations during ECMO, changes in platelet count and function, platelet monitoring techniques, bleeding risk, and future needs to best optimize patient management and care.

Bleeding disorders in adolescents with heavy menstrual bleeding in a multicenter prospective US cohort.

Heavy menstrual bleeding is common in adolescents. The frequency and predictors of bleeding disorders in adolescents, especially with anovulatory bleeding, are unknown. Adolescents referred for heavy menstrual bleeding underwent an evaluation of menstrual bleeding patterns, and bleeding disorders determined a priori. The primary outcome was the diagnosis of a bleeding disorder. Two groups were compared: anovulatory and ovulatory bleeding. Multivariable logistic regression analysis of baseline characteristics and predictors was performed. Kaplan Meier curves were constructed for the time from the first bleed to bleeding disorder diagnosis. In 200 adolescents, a bleeding disorder was diagnosed in 33% (n=67): low von Willebrand factor levels in 16%, von Willebrand disease in 11%, and qualitative platelet dysfunction in 4.5%. The prevalence of bleeding disorder was similar between ovulatory and anovulatory groups (31% vs. 36%; P=0.45). Predictors of bleeding disorder included: younger age at first bleed (OR: 0.83; 95%CI: 0.73, 0.96), Hispanic ethnicity (OR: 2.48; 95%CI: 1.13, 5.05), non-presentation to emergency department for heavy bleeding (OR: 0.14; 95%CI: 0.05, 0.38), and International Society on Thrombosis and Haemostasis (ISTH) Bleeding Assessment Tool score ≥4 (OR: 8.27; 95%CI: 2.60, 26.44). Time from onset of the first bleed to diagnosis was two years in the anovulatory, and six years in the ovulatory cohort (log-rank test, P<0.001). There is a high prevalence of bleeding disorders in adolescents with heavy periods, irrespective of the bleeding pattern. Among bleeding disorders, the prevalence of qualitative platelet dysfunction is lower than previously reported.

Novel Hermanksky-Pudlak Syndrome Type 6 Missense Variant Associated with Subclinical Oculocutaneous Albinism and Mild Bleeding

▪Qualitative disorders of platelets are often missed at clinical evaluation. Hermansky-Pudlak (HPS) syndrome is a rare genetic metabolic disorder with subtype specific clinical associations most prevalent in Puerto Rico with strong link to consanguinity. HPS is usually associated with albinism, visual impairment and a qualitative platelet dysfunction due to absence of dense granules. Ceroid accumulation can be associated with inflammatory bowel disease, pulmonary fibrosis and kidney disease. Ten variants have been described with types 1, 2 and 4 associated with severe disease whilst type 3, 5 and 6 is associated with mild disease. Little is known about types 7, 8, 9 and 10. A Caucasian adult female presented with a history of intermittent episodes of severe bleeding. She carried the diagnosis of probable von Willebrand's disease at presentation. This particular patient did not respond to cryoprecipitate infusion but bleeding stopped secondary to infusion of normal platelets, a clue to a platelet storage disorder. Hence she was re-investigated for a bleeding disorder and initial coagulation testing identified abnormal platelet aggregation and amplitude pattern to epinephrine. She was subsequently evaluated with platelet transmission electron microscopy and platelet flow cytometry at the Mayo Clinic Hematopathology. Platelet TEM showed complete absence of dense granules and a normal flow cytometry. HPS was suspected and initial genetic studies identified a variant genetic abnormality. Further studies were done at the NIH. Classical clinical features of HPS like nystagmus, and ocular albinism was not identified at initial neurological and ophthalmologic examination. But more detailed evaluation revealed subclinical oculocutaneous albinism. Genome wide SNP analysis showed regions of homozygosity including HPS 1 and HPS 6; deletions were not identified in these genes. Full length HPS1 transcript was amplified by PCR of genomic DNA. Targeted next-generation sequencing identified a novel homozygous missense variant [c.383T>C (p.V128A)] in HPS6. Reduced HPS6 mRNA levels were found in the patient's skin fibroblasts compared to cells from patients with HPS-1 and normal control cells. HPS6 protein expression in the patient's cells was also low and approximately 60% lower than that of normal cells. HPS is a rare platelet storage disorder that can often be missed. Platelet aggregation tests need to be followed up by platelet TEM and genetic testing to definitively diagnose this condition. Further work up has defined a new missense variant by SNP analysis, next generation sequencing and fibroblast culture. It is important to identify the subtype of HPS, because certain subtypes of HPS (HPS 1, 2 and 4) have clinical manifestations like progressive pulmonary fibrosis. Identification of the platelet storage disorder also helps in management of the bleeding diathesis. DisclosuresNo relevant conflicts of interest to declare.

Low Incidence of Bleeding Events With a Restrictive Platelet Transfusion Protocol in Patients With Cirrhosis and Concomitant End Stage Renal Disease

Introduction: Management of ascites in cirrhosis with concomitant end-stage renal disease (ESRD) presents a challenge as diuretic titration and transjugular portosystemic shunt (TIPS) effectiveness are limited. Patients are often managed with serial large volume paracentesis (LVPs); both quantitative and qualitative platelet dysfunction may increase LVP bleed risk. Society guidelines differ with respect to minimum platelet thresholds for safe LVP. The primary aim of this study was to characterize rate of bleeding in a population with cirrhosis and ESRD receiving LVP with a restrictive platelet transfusion strategy. Methods: Retrospective study of consecutive inpatients LVP at a tertiary medical center between January 2016 and December 2017. Institutional clinical census developed a protocol in which no patients received fresh frozen plasma (FFP), platelets or desmopressin prior to ultrasound guided LVP. Records tabulated: date/time of LVP, complete blood profile (CBC), INR and model for end stage liver disease (MELD score) on day of procedure, any blood products transfused during inpatient stay, and any angiogram procedures performed. Details of any secondary hospital encounter within 2 weeks of LVP reviewed. Results: 757 inpatients underwent usLVP. Mean INR, platelet count and MELD was 2.1 (1.7-2.8), 124 (11-157k) and 24 (21-36) respectively. 35% of patients had INRs > 2.0. 131 patients (17%) had platelet counts < 50k and 32 patients (4%) had < 30k. 260 patients (34%) were on renal replacement therapy RRT) at the time of usLVP. An additional 52 patients had Cr >2.0 (7%). Only 1 of 757 patients (0.13%) had post-LVP bleeding requiring transfusion of 2 units of packed red blood cells. No patient required angiogram intervention for bleeding and no patient died from LVP related complications. Conclusion: Incidence of bleeding with ultrasound guided LVP is very rare, even in a high risk patient population with severe renal dysfunction and thrombocytopenia. Prophylactic product transfusion or desmopressin do not appear warranted in this high risk population.

Comprehensive Evaluation of Bleeding Disorders in Adolescents with Heavy Menstrual Bleeding

Introduction: Unpredictable, prolonged or heavy menstrual bleeding (HMB) is not unusual in many adolescents soon after menarche. Anovulation, owing to immaturity of the hypothalamic-pituitary-ovarian axis, is often the cause of HMB; however, it may coexist and mask an underlying bleeding disorder (BD). Retrospective data in adolescents with HMB suggest a prevalence of BDs from 10 to 62%. Prospective studies with uniform hemostatic evaluation and concurrent quality of life (QoL) assessments have not been performed. The incidence of BDs in adolescents, especially those with anovulatory bleeding, remains unknown. Methods: In this ongoing prospective cohort study (targeted n=200), 130 adolescents referred for HMB to multidisciplinary Young Women's Blood Disorders Clinics were enrolled. An assessment of menstrual loss using pictorial blood assessment chart (PBAC) and bleeding symptoms using ISTH-bleeding assessment tool (BAT) was undertaken. Participants underwent a comprehensive evaluation determined a priori, including assessment of hypermobility, standardized laboratory evaluation (prothrombin time, activated partial thromboplastin time, fibrinogen, thrombin time, von Willebrand disease (VWD) panel, whole blood platelet aggregation with ATP secretion, factor assays (FIX and FXIII), global hemostasis and hyperfibrinolysis using ROTEM, and a pelvic ultrasound (US). Patient reported outcomes for health related QoL(HR-QoL) was completed. Results: The mean age of participants was 14 (range 11-18) and mean age at menarche was 11.7 yrs. (range: 9-16). The mean PBAC score, before contraceptive initiation, was 504 (range: 100- 1200) and the mean ISTH BAT score was 3.8 (range: 1-8) in all participants. 62% had anovulatory menstrual bleeding. An inherited BD and/or bleeding risk was diagnosed in 24.6% (n=32); 9% (n=12) were diagnosed with VWD, 5% (n=6) with qualitative platelet dysfunction and 2 subjects were found to be hemophilia A (HA) carriers. Low VWF levels (VWF:Rco 30-50%) were detected in 9% (n=12). 15% had evidence of mild systemic hyperfibrinolysis (lysis 3-8% on ROTEM) but none met the criteria for further investigation for an inherited disorder of hyperfibrinolysis . Of those without BD, 2 were diagnosed to have VWF exon 28 polymorphism, and 3 were referred and ultimately diagnosed with hypermobility syndrome by Genetics. One was found to have endometriosis by laparoscopy and 3 were diagnosed with PCOS. Of those with BDs (all with low VWF), 3 were diagnosed with hypermobility syndrome (total 6) and 4 with PCOS (total 7). US was normal in all subjects. The PBAC scores were higher in BDs (634 vs. 410; SD ± 275 p=0.002), irrespective of the pattern of bleeding. No differences were found in the ISTH BAT scores (after excluding HA carriers) (3.6 vs. 4.8; SD ± 1.19, p=0.06), initial hbg or ferritin levels between the two groups. Only 6% (n=8) with BDs required ED visit and/or hospitalization for HMB vs. 14% (n=18) without a BD, of which majority had anovulatory bleeding. On multivariate logistic regression, no predictors of BDs were found. Adolescents with BDs had a decreased HR-QoL compared to those without a BD (QoL score 58 vs.87; SD± 12.5, p=&lt;0.001) even after control of HMB and correction of anemia. Conclusions: Inherited BDs are common in adolescents with HMB, confer a decreased HR-QoL and can be associated with anovulatory bleeding. A comprehensive evaluation is required to unravel disorders causing HMB. In this ongoing study, at this time, no predictor of an inherited BD was found in adolescents with HMB. Data accrual from the fully powered, ongoing, prospective study may offer further data to develop an ideal tool with a scoring system to take into account all prevalent causes of HMB to accurately predict a BD in adolescents. Disclosures Zia: NHLBI K23: Research Funding. Journeycake:CSL: Consultancy; Biogen: Consultancy; Baxalta/Shire: Consultancy. Jain:Novo Nordisk: Honoraria; Bayer: Membership on an entity's Board of Directors or advisory committees; Biogen: Speakers Bureau. Sarode:CSL Behring: Consultancy, Honoraria.

Incidence of Platelet Dysfunction by Thromboelastography-Platelet Mapping in Children Supported with ECMO: A Pilot Retrospective Study.

Bleeding complications are common and decrease the odds of survival in children supported with extracorporeal membrane oxygenation (ECMO). The role of platelet dysfunction on ECMO-induced coagulopathy and resultant bleeding complications is not well understood. The primary objective of this pilot study was to determine the incidence and magnitude of platelet dysfunction according to thromboelastography (TEG(®))-platelet mapping (PM) testing. Retrospective chart review of children <18 years old who required ECMO at a tertiary level hospital. We collected TEG(®)-PM and conventional coagulation tests data. We also collected demographic, medications, blood products administered, and clinical outcome data. We defined severe platelet dysfunction as <50% aggregation in response to an agonist. We identified 24 out of 46 children on ECMO, who had TEG(®)-PM performed during the study period. We found the incidence of severe bleeding was 42% and mortality was 54% in our study cohort. In all samples measured, severe qualitative platelet dysfunction was more common for adenosine diphosphate (ADP)-mediated aggregation (92%) compared to arachidonic acid (AA)-mediated aggregation (75%) (p = 0.001). Also, ADP-mediated percent of platelet aggregation was significant lower than AA-mediated platelet aggregation [15% (interquartile range, IQR 2.8-48) vs. 49% (IQR 22-82.5), p < 0.001]. There was no difference in kaolin-activated heparinase TEG(®) parameters between the bleeding group and the non-bleeding group. Only absolute platelet count and TEG(®)-PM had increased predictive value on receiver operating characteristics analyses for severe bleeding and mortality compared to activated clotting time. We found frequent and severe qualitative platelet dysfunction on TEG(®)-PM testing in children on ECMO. Larger studies are needed to determine if the assessment of qualitative platelet function by TEG(®)-PM can improve prediction of bleeding complications for children on ECMO.

The management of immune thrombocytopenic purpura.

Thrombocytopenia, defined as a platelet count less than 100 × 109/L, is common in clinical practice and poses diagnostic and management difficulties. Haemostasis involves a delicate balance between procoagulant and anticoagulant mechanisms. The major components of haemostasis are platelets, coagulation factors, coagulation inhibitors, fibrinolysis and blood vessels.1 In severe thrombocytopenia, this haemostatic balance may be disturbed, leading to bleeding. Bleeding caused by thrombocytopenia is mucocutaneous and can present in different forms, which may include epistaxis, menorrhagia, petechiae, ecchymosis, subconjuctival haemorrhage and oozing of blood from surgical incision sites. Qualitative platelet disorders can also cause mucocutaneous bleeding. These qualitative platelet disorders can be hereditary or acquired. Acquired causes include uraemia in chronic renal disease and the antiplatelet action of drugs, such as aspirin.2 The pattern of bleeding caused by coagulation disorders is quite different from that caused by platelet abnormalities. Bleeding resulting from coagulation disorders is characterised by bleeding into the joints, muscles, and connective tissue.1 Definitive diagnosis of qualitative platelet dysfunction cannot be made in Malawi; in our context, especially, the importance of a good clinical history cannot be overstated. Quantitative platelet disorders can be easily diagnosed from a full blood count that reveals thrombocytopenia. One cause of thrombocytopenia is immune thrombocytopenic purpura (ITP), and this will be the topic of discussion in this scholarly corner paper.

Treatment of Anxiety Disorders and Comorbid Alcohol Abuse with Buspirone in a Patient with Antidepressant-Induced Platelet Dysfunction: A Case Report

The risk of abnormal bleeding with serotonin reuptake inhibitors has been known, but there is insufficient evidence base to guide pharmacological treatment of anxiety in patients with underlying haematological conditions. The following case report is about a 50-year-old female with generalized anxiety disorder, social phobia, obsessive compulsive disorder, and alcohol abuse where pharmacological treatment of anxiety symptoms has been difficult as it would lead to bruising due to the patient's underlying qualitative platelet dysfunction. Treatment with venlafaxine, citalopram, escitalopram, and clomipramine resulted in improvement and anxiety symptoms, as well as reduction in alcohol use, but pharmacological treatment has to be discontinued because of bruising and hematomas. In view of an active substance use disorder, benzodiazepines were avoided as a treatment option. The patient's anxiety symptoms and comorbid alcohol abuse responded well to pharmacological treatment with buspirone which gradually titrated up to a dose of 30 mg BID. Patient was followed for around a six-month period while she was on buspirone before being discharged to family doctor's care. Buspirone is unlikely to have a significant effect on platelet serotonin transponder and could be an effective alternative for pharmacological treatment of anxiety in patients with a bleeding diathesis.

The Early Post-Hemorrhage Coagulation Profile Is Characterized By Qualitative Platelet Dysfunction

Introduction: The coagulopathy of trauma remains to be fully elucidated. During our group's development of a Rhesus Macaque model of hemorrhagic shock, an isolated qualitative platelet dysfunction from baseline was suggested; this observation is supported by, limited, clinical reports dating to the Vietnam era. Our group proposed to further investigate the acute coagulopathy of hemorrhage and hypothesized that qualitative platelet dysfunction is an early component of the post-hemorrhage coagulation profile.

Acute Liver Failure: Managing Coagulopathy and the Bleeding Diathesis

Acute liver failure (ALF) is defined as a severe, sudden liver dysfunction that induces encephalopathy and coagulopathy (prothrombin time [PT/INR] > 1.5) within 26 weeks of the onset of symptoms (usually jaundice) in patients without previous liver disease. Quantitative and qualitative platelet dysfunction, reduced synthesis of clotting factors, increased consumption of factors (mainly II, V, VII, X), reduced clearance of both activated factors, and/or factor inhibitor complexes are among the most important proposed pathogenetic factors. A possible role might be also played by the diminished degradation of anticoagulants. Plasminogen activator inhibitor 1 (PAI-1) is increased, shifting the balance toward hypofibrinolysis, despite the elevated levels of tissue plasminogen activator (tPA). Although changes in coagulation parameters provide crucial information for the management of the patient with ALF, the optimal management of the hemostatic defects is far from being defined. Because spontaneous bleeding occurs rarely during ALF, measures to improve the bleeding diathesis (fresh frozen plasma, cryoprecipitate, platelet transfusion) are recommended only in patients with clinically significant bleeding or before placement of invasive devices. Antifibrinolytic drugs are used in some cases, but often empirically. The role of rFVIIa, even if promising, is still under debate.

Diagnosis and treatment of von Willebrand disease: new perspectives and nuances

In 1926, Erik von Willebrand, a Finnish internist andacademic, evaluated and described a 5-year-old girlwith extreme bleeding and bruising due to what hadbeen designated the A˚landic haemorrhagic diseaseby inhabitants of this archipelago island in the Gulfof Bothnia. Hjordis, the propositus, was the ninth of12 children born to a pedigree in which four femalesiblings had already died before the age of 4 withuncontrolled haemorrhage and in which 23 of 66family members, predominantly females, had expe-rienced significant bleeding and bruising complica-tions [1]. In fact, Hjordis herself eventually died atthe age of 13 during her fourth menstrual cycle.Professor von Willebrand mistakenly concluded thatthis bleeding diathesis was an unusual form ofhaemophilia and decided to label the new diseaseas pseudo-haemophilia to differentiate it from thesex-linked recessive haemophilia A. Little did vonWillebrand realize that this disease, eventually tobecomeeponymous[vonWillebranddisease(VWD)],would become the most commonly diagnosed con-genital bleeding disorder, with a prevalence rangingbetween 1 per 10 000 individuals to 1.3% [2]. Type1 VWD is the most common subtype, representingup to 75–80% of all cases while the subtype 3 VWDoccurs in approximately 1 per million population inthe United States and Europe [2]. Determination ofthe exact prevalence of VWD is hindered somewhatby the heterogeneity of clinical and diagnosticlaboratory features. Even Professor von Willebrandappreciated the challenges of diagnosing VWD as hecollaborated with Professor Rudolf Ju¨gens at theBerlin University to examine patients blood sampleswith a newly invented kapilla¨rtrombometer appa-ratus [3]. Although they were technically mistakenwhen they attributed the bleeding manifestations ofVWD to a platelet defect, their observations wereremarkably prescient since it was not until early1970s that the existence of a specific von Willebrandfactor (VWF) glycoprotein separate from factor VIIIwas finally appreciated and demonstrated to supportplatelet adhesion to the subendothelial matrix ofdamaged blood vessels.Over the last 81 years since von Willebranddescribed the bleeding disorder, there have beennumerous attempts and approaches to refine thediagnosis of the disease so that appropriate andefficacious treatment can be delivered. The clinicalphenotype of VWD includes, in part, information onwhether bleeding is spontaneous or related to surgi-cal or physical trauma; family history and inheri-tance pattern; menstrual history in women; age ofonset of bleeding (to distinguish between acquired vs.inherited coagulation disorders); and sites of bleed-ing(mucocutaneousvs.visceral,intra-articular,intra-muscular, or soft tissue locations). Subsequentlaboratory testing is necessary to exclude or confirmthe diagnosis and to further classify the subtype ofVWD. This article will focus on selected vagariesassociated with the ability to utilize clinical pheno-typic information gathered through the history andphysical examination to predict the presence ofVWD. The clinical diagnosis of VWD must be based,however, on more than physician suspicion andintuition. Thus, the need for confirmatory testing inthe laboratory. The frailties of conventional labora-tory testing for diagnosing VWD and the use of anin vitro surrogate of the bleeding time will also be

Acquired Factor IX (fIX) Deficiency Associated with a Multiple Myeloma.

Multiple myeloma is associated with bleeding disorders in about 15 % of patients. The pathophysiology is multifactorial and may be related to the paraprotein level. The bleeding tendency has been reported to be caused by thrombocytopenia, paraprotein-induced qualitative platelet dysfunction, inhibition of polymerization of fibrin monomers, monoclonal thrombin inhibitor, factor X deficiency, acquired von Willebrand syndrome and local tissue fragility secondary to amyloidosis. Here, we report the first case of acquired fIX deficiency associated with a multiple myeloma (MM) in a 54 year-old Caucasian man.The patient presented with a Monoclonal Gammapathy of Undetermined Significance (MGUS) (IgA lambda 15 g/L). His laboratory evaluation then revealed an activated prothrombin time (aPTT) of 37 s (normal 29–36 seconds) without any bleeding disorder. Three years later, the MGUS evolved into a stage III multiple myeloma (IgA lambda 55 g/L) and the patient presented a hemorrhage after a bone marrow biopsy. At this time, the coagulation tests showed an aPTT of 54 s, a thrombin time of 27 s (normal 20–25 seconds), a normal platelet count without any other abnormalities. Clotting factors assay revealed a fIX deficiency of 10 %. No inhibitor was found using the Bethesda method and no fIX mutation was detected in the patient DNA as well as in his sister's. After receiving chemotherapy (VAD-type chemotherapy and high-dose of Melphalan with autologous stem cells transplantation), the paraprotein concentration decreased to 9 g/L and the coagulation results returned to normal. Sixteen months later, the MM recurred (IgA lambda 78 g/L) and the patient presented hemorrhagic manifestations associated with an aPTT of 70 s and a fIX deficiency at 11 %. Factor IX deficiency and bleeding diathesis were detected in every MM relapses. He died during a severe bleeding event (epistaxis, hematuria and rectorrhagia) despite fIX concentrate treatments.The etiology of this acquired fIX deficiency is not clear. The simultaneous evolution of MM and fIX deficiency, and the absence of congenital hemophilia mutation confirm that it is an acquired deficiency. Nevertheless there is no fIX inhibitor. Until now no case of acquired fIX deficiency is described in the literature apart from Gaucher disease. Our hypothesis is that fIX can be adsorbed by the malignant plasma cells. We are currently performing immunostaining of fIX in the bone marrow of this patient to assess whether fIX is adsorbed by the medullar malignant cells.

Platelet function in autoimmune (idiopathic) thrombocytopenic purpura

Platelets play an essential role in the formation of haemostatic plugs. The quantitative defect of platelets in autoimmune (idiopathic) thrombocytopenic purpura (ITP) can result in bleeding complications, but most ITP patients have platelets with normal or enhanced function. Platelets in ITP are large, young, so-called “stress” platelets with increased platelet-associated autoimmune antibody (immunoglobulin G). Young stress platelets are more functional platelets, and their presence may account for bleeding times in ITP patients that are shorter than would be predicted on the basis of the patients' (low) platelet counts. Some ITP patients have significant mucocutaneous bleeding with platelet counts >50 × 109 l−1; this may be due to qualitative platelet dysfunction (e.g. brought about by inhibitory antiplatelet autoantibodies).

Platelet function in autoimmune (idiopathic) thrombocytopenic purpura.

Platelets play an essential role in the formation of haemostatic plugs. The quantitative defect of platelets in autoimmune (idiopathic) thrombocytopenic purpura (ITP) can result in bleeding complications, but most ITP patients have platelets with normal or enhanced function. Platelets in ITP are large, young, so-called "stress" platelets with increased platelet-associated autoimmune antibody (immunoglobulin G). Young stress platelets are more functional platelets, and their presence may account for bleeding times in ITP patients that are shorter than would be predicted on the basis of the patients' (low) platelet counts. Some ITP patients have significant mucocutaneous bleeding with platelet counts >50 x 10(9) l(-1); this may be due to qualitative platelet dysfunction (e.g. brought about by inhibitory antiplatelet autoantibodies).

In vitro assessment of platelet function.

With the realization that the skin bleeding time is often an unreliable measure of platelet function, efforts have been made to identify ways to assess qualitative platelet dysfunction. Currently available techniques measure platelet adhesion, platelet aggregation, the ability of platelets to retard or stop flow through fibers, and the contribution of platelets to in vitro clot formation. Glass bead adhesion, which continues to be performed in some laboratories, is gradually being replaced by measures of platelet adhesion to filters composed of glass fibers, Dacron fibers, or collagen. In each instance, anticoagulated platelet-rich plasma or whole blood flows through the filter under a regulated pressure gradient. The amount of blood flowing through the filter versus time and/or the time to filter occlusion are measured. Recent developments in platelet aggregation have focused on whole blood and stagnation point flow aggregation techniques. Whole blood aggregation does not require blood sample processing and accommodates blood obtained from citrated vacutainer tubes. Stagnation point flow measures both platelet adhesion and aggregation and may be able to detect pathologically-enhanced platelet function. Global measures of hemostasis attempt to simultaneously evaluate the adequacy of fluid phase coagulation and platelet function. Currently available techniques include Thromboelastography, SonoClot Analyzer, Hemodyne Hemostasis Analyzer, PITT, and Hemostatometry. Although each of these technologies have been shown to provide interesting data in the research setting, the ability of any of these techniques to detect abnormal or clinical inadequate platelet function remains to be established.

Increased reticulated platelets in dialysis patients

The purpose of this study was to measure the percent reticulated platelets and platelet counts in patients on chronic hemodialysis, peritoneal dialysis and normal volunteers. The relationship between the percent reticulated platelets and the platelet count can then be used to determine the rate of platelet turnover. Platelet rich plasma was obtained, platelets were fixed and incubated with thiazole orange and analyzed for the percent reticulated platelets by flow cytometry. Normal controls had a mean of 2.77 +/- 0.17% reticulated platelets while peritoneal dialysis patients had a mean percent reticulated platelets of 6.92 +/- 0.68 (P < 0.00001). Chronic hemodialysis patients had a mean percent reticulated platelets of 8.21 +/- 0.36 (P < 0.00001 vs. normal controls and P = 0.05 vs. peritoneal dialysis patients). Platelet counts did not differ significantly among the three groups. The identity of reticulated platelets was confirmed in experiments measuring platelet specific glycoproteins, experiments using RNase, and in mixing experiments with normal and uremic platelets and plasma. We conclude that dialysis patients have a marked increase in circulating reticulated platelets compared to normal controls, indicating accelerated platelet turnover. Increased platelet activation and turnover may contribute to the qualitative platelet dysfunction observed in dialysis patients.

Evaluation of the Thrombelastograph Targeted Coagulation Assessment

Extracorporeal circulation predisposes patients to hemorrhagic risk which may increase both homologous transfusion requirements and the need for pharmacological intervention. The aim of this study was to evaluate the efficacy of a new diagnostic coagulation assay utilizing the thrombelastograph (TEG). Following Institutional Review Board approval, blood was drawn from healthy, non-medicated volunteers and four in vitro coagulopathic conditions were created, which included: hyperfibrinolysis (100% lysis), hypofibrinogenemia (&lt;50 mg/dl), and both qualitative (1000 ug/ml nitroglycerin) and quantitative (&lt;50 K/mm3) platelet abnormalities. Each of these four blood samples was then divided among four vials that contained known quantities of either: aminocaproic acid, fresh frozen plasma (FFP), platelet concentrate, or heparinase, and TEG profiles were completed. Twenty-one samples were evaluated and the following results were obtained. Hyperfibrinolysis- 100% correction of fibrinolytic potential in the aminocaproic acid vial, but none in the other vials. Qualitative platelet dysfunction- significantly improved time to coagulation in the platelet vial but not in the FFP, heparinase or aminocaproic acid vials. Quantitative platelet dysfunction- no significant difference observed between any vials. Hypofibrinogenemia- significant improvement in the TEG index in the FFP vial (-2.7 ± 0.5) when compared to the aminocaproic acid ( -8.6 ± 2.5, p&lt;.001), platelet (-6.5 ± 0.5, p&lt;.01) and heparinase (-8.8 ± 2.5, p&lt;.001) vials. We conclude that this coagulation assessment assay may help in identifying the specific source of bleeding during surgeries where hyperfibrinolysis, hypofibrinogenemia, or qualitative platelet dysfunctions are present.