Laboratory issues in diagnosing abnormalities of protein C, thrombomodulin, and endothelial cell protein C receptor

Met343Val mutation disrupts the shuttling of Trp380 leading to a low-activity conformer of activated protein C and causes thrombosis

BACKGROUND

Protein C (PC) pathway serves as a major defense mechanism against thrombosis by the activation of PC through the thrombin-thrombomodulin complex and subsequent inactivation of the activated factor (F)V (FVa) and FVIII (FVIIIa) with the assistance of protein S, thereby contributing to hemostatic balance. We identified 2 unrelated patients who suffered from recurrent thrombosis and carried the same heterozygous mutation c.1153A>G, p.Met343Val (M343V), in PROC gene. This mutation had not been previously reported.

OBJECTIVES

To explore the molecular basis underlying the anticoagulant defect in patients carrying the M343V mutation in PROC.

METHODS

We expressed PC-M343V variant in mammalian cells and characterized its properties through coagulation assays.

RESULTS

Our findings demonstrated that while activation of mutant zymogen by thrombin-thrombomodulin complex was slightly affected, cleavage of chromogenic substrate by APC-M343V was significantly impaired. However, Ca2+ increased the cleavage efficiency by approximately 50%. Additionally, there was a severe reduction in affinity between APC-M343V and Na+. Furthermore, the inhibitory ability of APC-M343V toward FVa was markedly impaired. Structural and simulation analyses suggested that Val343 might disrupt the potential hydrogen bonds with Trp380 and cause Trp380 to orient closer to His211, potentially interfering with substrate binding and destabilizing the catalytic triad of APC.

CONCLUSION

The M343V mutation in patients adversely affects the reactivity and/or folding of the active site as well as the binding of the physiological substrate to the protease, resulting in impaired protein C anticoagulant activity and ultimately leading to thrombosis.

Thrombophilia Screening: Not So Straightforward

Although inherited thrombophilias are lifelong risk factors for a first thrombotic episode, progression to thrombosis is multifactorial and not all individuals with inherited thrombophilia develop thrombosis in their lifetimes. Consequently, indiscriminate screening in patients with idiopathic thrombosis is not recommended, since presence of a thrombophilia does not necessarily predict recurrence or influence management, and testing should be selective. It follows that a decision to undertake laboratory detection of thrombophilia should be aligned with a concerted effort to identify any significant abnormalities, because it will inform patient management. Deficiencies of antithrombin and protein C are rare and usually determined using phenotypic assays assessing biological activities, whereas protein S deficiency (also rare) is commonly detected with antigenic assays for the free form of protein S since available activity assays are considered to lack specificity. In each case, no single phenotypic assay is capable of detecting every deficiency, because the various mutations express different molecular characteristics, rendering thrombophilia screening repertoires employing one assay per potential deficiency, of limited effectiveness. Activated protein C resistance (APCR) is more common than discrete deficiencies of antithrombin, protein C, and protein S and also often detected initially with phenotypic assays; however, some centres perform only genetic analysis for factor V Leiden, as this is responsible for most cases of hereditary APCR, accepting that acquired APCR and rare F5 mutations conferring APCR will go undetected if only factor V Leiden is evaluated. All phenotypic assays have interferences and limitations, which must be factored into decisions about if, and when, to test, and be given consideration in the laboratory during assay performance and interpretation. This review looks in detail at performance and limitations of routine phenotypic thrombophilia assays.

Ser252Asn Mutation Introduces a New N-Linked Glycosylation Site and Causes Type IIb Protein C Deficiency

BACKGROUND

 Protein C (PC) is a vitamin K-dependent anticoagulant serine protease zymogen which upon activation by the thrombin-thrombomodulin (TM) complex downregulates the coagulation cascade by degrading cofactors Va and VIIIa by limited proteolysis. We identified a thrombosis patient who carried a heterozygous mutation c.881G > A, p.Ser252Asn (S252N) in PROC. This mutation was originally described in a report of novel mutations in patients presenting with defective PC anticoagulant activity in Paris. The research identified PC-S252N (the "Paris" mutation) in a propositus and her family members and highlighted the critical role of Ser252 in the anticoagulation process of activated PC (APC).

MATERIAL AND METHODS

 We expressed the PC-S252N mutant in mammalian cells and characterized the properties in coagulation assays to decipher the molecular basis of anticoagulant defect of this mutation.

RESULTS

 We demonstrated that PC-S252N had a diminished ability to TM binding, which resulted in its impaired activation by the thrombin-TM complex. However, APC-S252N exhibited a slightly stronger cleavage capacity for the chromogenic substrate. Meanwhile, the catalytic activity of APC-S252N toward FVa was significantly reduced. Sequence analysis revealed that Ser252 to Asn substitution introduced a new potential N-linked glycosylation site (252NTT254) in the catalytic domain of PC, which adversely affected both the activation process of PC and anticoagulant activity of APC.

CONCLUSION

 The new N-glycosylation site (252NTT254) resulting from the mutation of Ser252 to Asn252 in PROC affects the overall structure of the protease, thereby adversely affecting the anticoagulant function of protein C. This modification has a negative impact on both TM-promoted activation of protein C and APC cleavage of FVa, ultimately leading to thrombosis in the patient.

Successful ECMO treatment in patients with cerebral hemorrhage and PROC gene mutation associated with VTE: a case report

In this report, we report a case of a middle-aged male, admitted to the ICU with cerebral hemorrhage resulting from a severe high-altitude fall. The patient encountered significant challenges in oxygenation index correction, attributed to extensive embolism in both the primary and branch pulmonary arteries. Consequently, the patient underwent an immediate initiation of veno-arterial extracorporeal membrane oxygenation (VA-ECMO) therapy, persisting for 20 days. During this treatment period, a mutation in the protein C (PROC) gene was identified. The medical team meticulously navigated the delicate balance between anticoagulation and bleeding risks. Eventually, the patient was successfully weaned off VA-ECMO and subsequently discharged. This report aims to delve into the etiology and therapeutic approaches of this uncommon case, with the intention of offering insightful reference for managing similar clinical scenarios in the future.

Two cases of venous thromboembolism in siblings after splenectomy due to a novel PROC gene mutation

BACKGROUND

Venous thromboembolism(VTE)is a common multifactorial disease. Anticoagulant protein deficiency is the most usual hereditary thrombophilia in the Chinese people, which includes protein C(PC), protein S and antithrombin deficiencies.

CASE PRESENTATION

A retrospective analysis was conducted on clinical manifestations, laboratory tests, genetic information, and other relevant data of siblings diagnosed with VTE in 2020 at the Department of Pediatrics of Shenzhen Second People's Hospital. The proband, a 12-year-old female, was admitted to the hospital in December 2020 with a complaint of pain in the left lower limb for four days. The examination found that the PC activity was 53%, and B-ultrasound showed bilateral thrombosis of the great saphenous vein in the thigh segment. The proband's younger brother, a 10-year-old male, was admitted to the hospital in January 2021 due to right lower limb pain for two weeks. PC activity is 40%. B-ultrasound showed superficial venous thrombosis in the left lower limb and upper limb. Both siblings suffered from thalassemia and underwent splenectomy before recurrent thrombosis occurred. The proband's mother was asymptomatic, and her PC activity was 45%. Both cases were treated with warfarin anticoagulation, and their symptoms improved. The proband's mother was found to have a heterozygous mutation at this locus through Sanger sequencing.

CONCLUSION

Protein C deficiency should be considered for venous thromboembolism in childhood. The heterozygous mutation 1204 A > G in PROC exon 9 in this family is reported for the first time.

Acute Portal Vein Thrombosis as an Initial Presentation of Protein C Deficiency: A Case Report

Protein C (PC) is an essential vitamin K-dependent protein that regulates thrombosis and hemostasis in the body. A mutation in the PROC gene on chromosome 2q14.3 results in PC deficiency. The clinical presentation of PC deficiency can vary, ranging from a single vein thrombosis to disseminated intravascular coagulation, purpura fulminans, or even life-threatening complications such as sepsis. Here, we present a case of a 37-year-old female who was found to have acute portal vein thrombosis as an initial presentation of PC deficiency. She presented to the hospital with acute onset of abdominal pain associated with nausea, blood-streaked emesis, and bloody bowel movement.

A case of polycystic ovary syndrome with inevitable miscarriage and multi-site venous thrombosis caused by hereditary protein C deficiency

BACKGROUND

Polycystic ovarian syndrome (PCOS) affects up to 18% of reproductive-aged women and raises the risk of venous thromboembolic disease (VTE), due to metabolic features and an apparent fibrinolytic state. Recent studies have shown an increased risk of VTE (1.5- to 2-fold) in patients with PCOS as compared to those without PCOS. Mutations in the Protein C (PC) gene (PROC) lead to deficiency or dysfunction of the protein, Protein C deficiency is the main clotting physiological inhibitor of protein C cofactors, and is a risk factor for venous thrombosis, which can cause a variety of events, including miscarriage. This case report proposes a correlation between PCOS, protein C deficiency, venous thrombosis and inevitable miscarriage.

CASE PRESENTATION

A 33-year-old Chinese woman was diagnosed with Polycystic Ovary Syndrome (PCOS) in 2015. During the course of treatment, she took ethinylestradiol and cyproterone acetate tablets for more than one year. In 2016, she was sent to a hospital for emergency care due to explosive thrombosis (thrombosis in multiple parts of the body and pulmonary thrombosis). In 2020, the patient became pregnant via natural means and came to our hospital for treatment. During the second trimester, she experienced an inevitable miscarriage. High-throughput sequencing (NGS) of peripheral blood lymphocytes revealed that the patient had a protein C deficiency resulting from a heterozygous mutation deletion of 572_574 in exon 7.

CONCLUSION

PC deficiency in conjunction with PCOS and the concomitant use of oral contraceptive (COC) would increase the risk of VTE, especially in the early stages of COC use.

Hereditary protein C deficiency with portal vein thrombosis in a Chinese male: A case report

Hereditary protein C deficiency (PCD) is caused by mutation in the PC gene (PROC). The homozygous mutation form of PCD is rare. Furthermore, in Asia, cases of noncirrhotic patients with portal vein thrombosis (PVT) secondary to PCD have been rarely reported. The present study reported the case of a patient with PVT due to hereditary PCD. Of note, the mutation of PROCc.152G>A was observed in the patient of the present study. According to the current literature, there has been no previous report regarding the mutation of this gene in China. The patient suffered abdominal pain for 20 days, which was accompanied by vomiting for 2 days. Multiple ulcers and diverticula in the sigmoid colon, as well as erosive small ulcers throughout the colon, were discovered during a colonoscopy. Abdominal angiography indicated thrombosis of the portal vein and its branches. Furthermore, laboratory parameters indicated a hypercoagulable state with normal PC antigen values but decreased PC activity. The discovery of blood coagulation-related genes suggested that homozygous mutation in PC resulted in an amino acid missense mutation. Anticoagulants were prescribed after a diagnosis of type II hereditary PCD with PVT was made. After 15 days, the blood coagulation function of the patient was restored to normal and the symptoms were substantially alleviated. Hence, the present study expanded the mutation spectrum of PROC in China and reaffirmed the value of anticoagulant therapy in PCD.

Severe protein C deficiency in a newborn caused by a homozygous pathogenic variant in the PROC gene: a case report

Background

Severe protein C deficiency is a rare and inherited cause of thrombophilia in neonates. Protein C acts as an anticoagulant, and its deficiency results in vascular thrombosis. Herein, we report a case of protein C deficiency with a homozygous pathogenic variant in a term neonate, with good outcomes after proper treatment.

Case presentation

A four-day-old male newborn was transferred to the Seoul National University Hospital on account of dark red to black skin lesions. He was born full-term with an average birth weight without perinatal problems. There were no abnormal findings in the prenatal tests, including intrauterine sonography. The first skin lesion was observed on his right toes and rapidly progressed to proximal areas, such as the lower legs, left arm, and buttock. Under the impression of thromboembolism or vasculitis, we performed a coagulopathy workup, which revealed a high D-dimer level of 23.05 μg/ml. A skin biopsy showed fibrin clots in most capillaries, and his protein C activity level was below 10%, from which we diagnosed protein C deficiency. On postnatal day 6, he experienced an apnea event with desaturation and an abnormal right pupillary light reflex. Brain computed tomography showed multifocal patchy intracranial hemorrhage and intraventricular hemorrhage with an old ischemic lesion. Ophthalmic examination revealed bilateral retinal traction detachments with retinal folds. Protein C concentrate replacement therapy was added to previous treatments including steroids, prostaglandin E1, and anticoagulation. After replacement therapy, there were no new skin lesions, and the previous lesions recovered with scarring. Although there were no new brain hemorrhagic infarctions, there was ongoing ischemic tissue loss, which required further rehabilitation. Ophthalmic surgical interventions were performed to treat the bilateral retinal traction detachments with retinal folds. Molecular analysis revealed a homozygous pathogenic variant in the PROC gene.

Conclusion

Severe protein C deficiency can manifest as a fatal coagulopathy in any organ. Early diagnosis and proper treatment, including protein C concentrate replacement, may improve outcomes without serious sequelae.

In vitro diagnostics for the medical dermatologist. Part II: Hypercoagulability tests

The skin often provides initial clues of hypercoagulability with features such as livedo reticularis, livedo racemosa, retiform purpura, necrosis, and ulcerations. Because these cutaneous manifestations are nonspecific, laboratory testing is often needed to evaluate for underlying causes of hypercoagulability. Importantly, these disorders are reported to be the most common mimicker, resulting in an erroneous diagnosis of pyoderma gangrenosum. Understanding inherent properties of, and indications for, available tests is necessary for appropriate ordering and interpretation of results. Additionally, ordering of these tests in an indiscriminate manner may lead to inaccurate results, complicating the interpretation and approach to management. This second article in this continuing medical education series summarizes information on methodology, test characteristics, and limitations of several in vitro laboratory tests used for the work up of hypercoagulability and vasculopathic disease as it pertains to dermatologic disease.

Pathogenic variants of PROC gene caused type II activity deficiency in a Chinese family: A case report

RATIONALE

Hereditary Protein C (PC) deficiency is a rare genetic disorder caused by PROC gene mutation. In this article, we report a case of PC deficiency in a Chinese family due to a novel PROC gene mutation.

STUDY SUBJECT

The proband presented with recurrent cerebral infarction over the course of the previous 3 years. He was admitted to the hospital due to signs of mental retardation.

DIAGNOSES

Physical examination, laboratory tests, and magnetic resonance imaging demonstrated that the proband had a manifestation of PC deficiency that included acute cerebral infarction. DNA sequencing analysis revealed a missense variant, c.1015G > A (p.V339 M from valine to methionine) in exon 9 of the PROC gene. In addition, Sanger sequencing confirmed that the proband's son was heterozygous for the same variant. Therefore, the PROC gene mutation was transmitted in an autosomal dominant inheritance manner.

INTERVENTIONS

The patient was treated with a daily dosage of Warfarin (3.5 mg) and was scheduled to undergo regular blood coagulation tests.

OUTCOMES

At the 3-month follow-up appointment, the patient showed improvements in his overall health condition.

LESSONS

We identified a novel missense mutation in the PROC gene in a Chinese family which caused a decrease in the PC antigen level and recurrent cerebral infarction.

Laboratory Limitations of Excluding Hereditary Protein C Deficiency by Chromogenic Assay: Discrepancies of Phenotype and Genotype

Protein C (PC) deficiency is associated with an increased risk for venous thromboembolism (VTE). In daily practice, exclusion of a hereditary PC deficiency is often based on a single determination of PC activity, by either clotting time–based or mostly chromogenic assay. However, diagnosis of hereditary PC deficiency is challenging due to several laboratory and clinical limitations. We compared the potential of PC activity values measured by either chromogenic or clotting time–based assay to predict a variation in the PROC gene. One hundred one (35%) of 287 patients carried variations within the PROC gene, including 2 previously not published variations. In 20 (20%) patients with identified variation, PC activity, determined by chromogenic assay, was within the reference range. For prediction of an underlying genetic defect determined by chromogenic and clotting time–based assay, sensitivity was 80% versus 99%, specificity 75% versus 18%, positive predictive value 64% versus 39%, and negative predictive value (NPV) 88% versus 97%. The lower NPV of chromogenic versus clotting time–based PC assay can be mainly explained by the presence of PC deficiency type IIb. Following our proposed diagnostic algorithm, additional measurement of PC activity by clotting time–based assay in case of a positive VTE history improves detection of this subtype of PC deficiency. Considering potential therapeutic consequences for primary and especially for secondary VTE prophylaxis, genetic analysis is required not only for confirmation but also for clarification of PC deficiency.

Congenital protein C deficiency and thrombosis in a dog

Congenital protein C deficiency is an important cause of thrombosis in humans but is not described in dogs. A 4‐year‐old Hungarian Vizsla was presented for investigation of acute onset of ascites. Computed tomography of the chest and abdomen and echocardiography confirmed a large thrombus within the right ventricle. A cause for thrombosis was not initially identified. The clinical signs resolved rapidly and the dog was administered clopidogrel and discharged. Plasma protein C activity measured 2 and 6 weeks later was markedly lower than expected on both occasions. All known causes of acquired protein C deficiency were excluded, and the dog was diagnosed with a congenital protein C deficiency. After diagnosis, the administration of clopidogrel was stopped and administration of rivaroxaban was started. The dog remains well with no evidence of recurrent thrombosis with 6 months of follow‐up.

Recommendations for clinical laboratory testing for protein C deficiency, for the subcommittee on plasma coagulation inhibitors of the ISTH

Inherited protein C (PC) deficiency increases risk of venous thromboembolism (VTE) by 5 to 10-fold in thrombosis-prone families; however, heterozygous PC deficiency alone does not determine that a subject has thrombophilia. Protein C deficient subjects, who lack additional inherited risk factors such as factor V Leiden or have no major acquired risk factors, may not suffer from VTE. In addition, PC deficiency may be acquired, often due to vitamin K antagonist treatment or liver disease. In contrast, homozygous or compound heterozygous PC deficiencies are rare and serious disorders, and affected infants are often in families with no history of PC deficiency or thrombosis. Laboratories commonly use the chromogenic PC assay to diagnose deficiency. Chromogenic assay is recommended due to its good specificity, but this assay fails to detect the rare type 2b deficiency where the defect is due to poor interaction with calcium ions, phospholipid, protein S, and factor Va and factor VIIIa. The clotting-based assay of PC is capable of detecting type 2b deficiency but it has reduced specificity. Importantly, PC level varies with age, adult reference ranges cannot be applied to babies or children and levels may not reach those of adults even in adolescence. Pre-analytical variables in the specimen affect measurement of PC, and can be assay-dependent; for example, a partially clotted sample will have falsely raised PC level by chromogenic assay but reduced level by clotting-based assay. Direct oral anticoagulants falsely raise PC level in the clotting-based assay but the standard chromogenic assay is unaffected.

Protein C deficiency; PROC gene variants in a Danish population

INTRODUCTION

Protein C deficiency is a heritable thrombophilia caused by numerous different genetic alterations in the protein C (PROC) gene. We aimed to identify variants causing protein C deficiency in a Danish population.

MATERIAL AND METHODS

Sanger sequencing of the PROC gene was performed in 20 probands and 26 relatives. In total, 30participants were previously diagnosed with protein C deficiency. Protein C activity was measured by a chromogenic substrate method (N = 40) and antigen level by an enzyme-linked immunosorbent assay (N = 26).

RESULTS

Ten different single nucleotide variants were detected in 13 probands (65%) and in seven of the relatives previously diagnosed with protein C deficiency. Five variants were novel. The median protein C activity level was lower in participants with an identified variant (50% (range: 38-75%)) than in protein C deficient participants without a variant (65% (range: 36-73%); P = 0.18). A protein C activity of 57% resulted in the highest detection rate (12/13 (92%)). Likewise, the median antigen level was lower in participants with detectable variants than in participants without (49% (range: 35-99%) vs 70% (range: 41-101%); P = 0.09). No difference was found in venous thromboembolism (VTE) prevalence comparing participants with (12/20 (60%)) and without (7/10 (70%)) a variant (P = 0.59).

CONCLUSION

In a Danish population, a PROC gene variant was identified in 67% of participants previously diagnosed with protein C deficiency. Five variants were novel. The study confirmed an association between biochemical severity and the presence of a PROC gene variant. The VTE risk did not seem to differ between protein C deficient participants with and without a variant.

Protein C Deficiency

Protein C (PC) deficiency is a heritable or acquired risk factor for thrombophilia, with presentations varying from asymptomatic to venous thromboembolism to neonatal purpura fulminans, a life-threatening disorder. Hereditary PC deficiency is caused by mutation in the PC (PROC) gene located on chromosome 2q14.3. Heterozygous and acquired PC deficiencies are more common than homozygous deficiency. The recommended initial laboratory test measures PC activity using either clot-based or chromogenic methods. There are numerous potential interferences in PC activity testing that may result in either false-positive (falsely low activity) or false-negative (falsely normal or elevated activity) results. In the present review, we discuss common clinical presentations; laboratory testing, with a focus on potential assay interferences; treatment options; and prognosis in patients with PC deficiency.

Ménétrier's disease presenting as recurrent unprovoked venous thrombosis: a case report

BACKGROUND

Acquired thrombophilia is a potential sequela of malignancy, chronic inflammation, and conditions characterized by severe protein deficiency (for example, nephrotic syndrome, protein-losing enteropathy). As such, venous thrombosis is often a feature, and occasionally a presenting sign, of systemic disease. Ménétrier's disease is a rare hyperplastic gastropathy that may lead to gastrointestinal protein loss and hypoalbuminemia. To date, reports of venous thrombosis associated with Ménétrier's disease are exceedingly scarce.

CASE PRESENTATION

We report the case of a 40-year-old white man who presented with unprovoked deep venous thrombosis, pulmonary embolism, and renal vein thrombosis. Upon receiving therapeutic anticoagulation, he developed severe gastrointestinal bleeding, and endoscopic evaluation led to a diagnosis of Ménétrier's disease. A laboratory workup revealed deficiency of protein C, protein S, and antithrombin III, as well as markedly elevated levels of factor VIII. He was determined to have an acquired thrombophilia as a direct result of Ménétrier's disease.

CONCLUSIONS

This case describes an acquired thrombophilic state in a patient with Ménétrier's disease and profound hypoalbuminemia. Although this association is rarely described, we discuss the probable mechanisms leading to our patient's thrombosis. Specifically, we posit that his gastrointestinal protein loss led to a deficiency of several anticoagulant proteins and a compensatory elevation in factor VIII, as occurs in nephrotic syndrome and inflammatory bowel disease. Of note, this patient's recurrent venous thrombosis was the initial clinical sign of his gastrointestinal pathology.

Donor Selection and Prophylactic Strategy for Venous Thromboembolic Events in Living Donors of Liver Transplantation Based on Results of Thrombophilia Screening Tests

Background

We reported a strategy of thrombophilia testing-guided venous thromboembolic events (VTE) prophylaxis for living donors of liver transplantation in 2011. The aim of the present study was to evaluate the safety and efficacy of this protocol for VTE prophylaxis.

Material/Methods

Thrombophilia testing, including protein S (PS), protein C (PC), antithrombin (AT) III, and anti-phospholipid antibody (APLA), was performed in 306 living donor candidates between July 2005 and June 2016. Donors who met any of the criteria of PS <60%, PC <64%, AT-III <70%, and positive APLA were classified into the borderline group and received continuous venous infusion of heparin immediately after surgery, in addition to use of elastic stockings and intermittent pneumatic compression (IPC) until patients were ambulatory. Other donors who were classified into the normal group used elastic stockings and IPC with no anticoagulants. The efficacy and safety endpoints were VTE occurrence and bleeding events, respectively.

Results

PS was considerably decreased in 3 candidates and PC was considerably reduced in 1 candidate, and they were excluded for high risk of VTE. Seventeen candidates in the borderline group and 137 in the normal group underwent donor surgery. One donor in the borderline group developed a wound hematoma. Postoperative complications were similar between the 2 groups. None of the donors in either group developed VTE.

Conclusions

Thrombophilia testing-guided VTE prophylaxis is safe and may contribute to reduced VTE risk in donors, although further investigations are warranted to assess the necessity of thrombophilia testing prior to surgery among living donors.

SUB-ACUTE STENT THROMBOSIS AND IN-STENT RESTENOSIS ASSOCIATED WITH ANTIPLATELETS CLOPIDOGREL RESISTANCE AND PROTEIN S DEFICIENCY

Protein S deficiency and antiplatelets clopidogrel resistance may uncommonly be responsible for coronary artery thrombosis. Hereby we report a patient presented with coronary disease, who had undergone PCI. However, two days later the patient was found in-stent thrombosis. Primary PCI was performed later with good result, but after 4 months evaluation with treadmill test we found significant ST depression in related region. It was suspected the patient had in-stent re-stenosis incidence. Further hematologic investigation showed that this patient had antiplatelets clopidogrel resistance and protein S deficiency. Double antiplatelet with another kind of antiplatelets and anticoagulant had given in this case. However, the remaining consideration is the choice for reperfusion strategy.

[Gene diagnosis of four patients with protein C deficiency]

目的

探讨蛋白C缺陷症的分子发病机制。

方法

对4例蛋白C缺陷症患者进行常规诊断和基因分析。

结果

①例1，女，40岁。临床诊断：左下肢深静脉血栓形成。蛋白C活性（PC∶C）48%，蛋白S活性（PS∶C）26.3%，抗凝血酶活性（AT∶C) 75.6%。基因检测结果：蛋白C基因（PROC）启动子C5156T杂合突变、2号外显子区域存在A6578T杂合突变。给予抗凝、溶栓、滤器植入等治疗，症状好转出院。②例2，女，32岁。临床诊断：双下肢深静脉血栓，双上、下肢缺血，双下肢皮肤软组织感染。PC∶C 27%，PS∶C 22.9%，AT∶C 86.7%。基因检测结果：PROC基因启动子C5156T杂合突变、A5045T杂合突变。给予抗凝、抗感染等治疗，因呼吸衰竭、感染性休克、DIC死亡。③例3，女，28岁。临床诊断：右髂静脉及股深静脉血栓。PC∶C 58%，PS∶C 57.3%，AT∶C 80.8%。基因检测结果：PROC启动子C4867T杂合突变，7号外显子12702-12704 AGA (Arg192）或12705-12707 AGA（Arg193）杂合缺失，9号外显子G15240A杂合突变。给予抗凝、溶栓、滤器植入等治疗，症状好转出院。④例4，男，30岁。临床诊断：左下肢深静脉血栓，双下肺动脉栓塞伴双下肺梗死。PC∶C 50%，PS∶C 75.0%，AT∶C 89.1%。基因检测结果：PROC启动子C4867T纯合突变、G4880A纯合突变和A5045T杂合突变，2号外显子T6589C杂合突变。给予抗凝、溶栓、滤器植入等相关治疗，症状好转出院。⑤多态性分析：PROC基因启动子C4867T杂合突变、G4880A纯合突变、C5156T杂合突变为PROC启动子多态性位点。

结论

PROC启动子多态性位点G4880A、C4867T、C5156T，错义突变A5045T、A6578T、G15240A，缺失突变AGA12702-12704del或12705-12707del可能与蛋白C缺陷症有关。PROC启动子错义突变A5045T、A6578T、G15240A，缺失突变AGA12702-12704del或12705-12706del是国际首次报告。

Severe Congenital Protein C Deficiency: Practical Aspects of Management

Subcutaneous (SC) protein C (PC) was used in a child with purpura fulminans secondary to severe congenital PC deficiency. For maintenance, PC 80-120 IU/kg, given over 60-90 min SC Q48hr, has been successful as a home therapy for more than 3 years. The treatment was monitored by measuring trough PC chromogenic activity (target ≥15%) and D-dimer levels. No change in clinical course was appreciated after discontinuing enoxaparin (and leaving the patient on prophylactic PC replacement alone). A significant discrepancy between clotting-based and chromogenic-based PC activity is shown.

Assessment of the relationships among coagulopathy, hyperfibrinolysis, plasma lactate, and protein C in dogs with spontaneous hemoperitoneum

OBJECTIVE

To relate coagulation and fibrinolysis derangements to shock severity as reflected by plasma lactate concentrations in dogs with spontaneous hemoperitoneum (SHP) and determine the impact on transfusions.

DESIGN

Prospective, observational, case-control study.

SETTING

Three veterinary teaching hospitals.

ANIMALS

Twenty-eight client-owned dogs with SHP and 28 breed- and age-matched control dogs.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Blood samples for platelet counts, coagulation, and anticoagulant assays (prothrombin time, activated partial thromboplastin time, fibrinogen, antithrombin, and protein C, thromboelastography [TEG]), fibrinolysis testing (d-dimer and TEG lysis parameters with and without the addition of 50 U/mL of tissue plasminogen activator [TEG LY30 measured with the addition of 50 U/mL of tPA to the blood sample, LY3050 and TEG LY60 measured with the addition of 50 U/mL of tPA to the blood sample, LY6050 ; LY30 and LY60]), and plasma lactate as an indicator of severity of shock were collected from SHP dogs at the time of diagnosis. SHP dogs were hypocoagulable (prolonged prothrombin time and activated partial thromboplastin time, decreased TEG maximum amplitude) and hyperfibrinolytic (increased LY3050 and TEG LY6050 ) compared to controls. The severity of hypocoagulability was related to protein C activity, while the severity of hyperfibrinolysis was related to plasma lactate concentration. Among the 18 dogs discharged from the hospital, LY3050 was significantly associated with the dose of fresh frozen plasma administered, but none of the parameters were associated with the dose of red blood cells administered.

CONCLUSIONS

Dogs with SHP have evidence of hypocoagulability, protein C deficiency, and hyperfibrinolysis. Parameters of hyperfibrinolysis were related to plasma lactate concentrations and volume of plasma transfused during hospitalization. These derangements resemble those found in people with acute coagulopathy of trauma and shock, and activation of protein C may be a common feature to both syndromes.

Distinct frequencies and mutation spectrums of genetic thrombophilia in Korea in comparison with other Asian countries both in patients with thromboembolism and in the general population

Hereditary natural anticoagulant deficiencies are the major cause of genetic thrombophilia in Asia. Given the growing acknowledgment of the risk of venous thromboembolism in Asian populations, we investigated the frequency and mutation spectrums of natural anticoagulant deficiency in Korea. The group of patients consisted of consecutive patients with venous thromboembolism screened for thrombophilia. Genetic tests were performed on suspicion of natural anticoagulant deficiency. For the population group, >3,000 individuals were screened from routine check-ups, and those with a low level (<1(st) percentile) of natural anticoagulant underwent genetic tests. Mutations were detected by direct sequencing of PROC, PROS1, and SERPINC1, followed by additional multiplex ligation-dependent probe amplification for PROS1 and SERPINC1 for dosage mutations. Among 500 patients screened, 127 were suspected of having a natural anticoagulant deficiency, and this was genetically confirmed in 71: protein C deficiency in 36 (50.7%), antithrombin deficiency in 21 (29.6%), and protein S deficiency in 14 (19.7%). Among 3,129 individuals from the population who were screened, the frequency of natural anticoagulant deficiency was ~1.0%: antithrombin deficiency 0.49%, protein C deficiency 0.35%, and protein S deficiency 0.16%. Two PROC mutations causing type I protein C deficiency were prevalent (Arg211Trp and Met406Ile in patients and Arg211Trp in the population). Two SERPINC1 mutations causing type II antithrombin deficiency, Arg79Cys and Ser158Pro, were prevalent in the population group. This is the first study on the genetic epidemiology of natural anticoagulant deficiencies in Korea. The results demonstrated that the frequencies and spectrum of mutations underlying genetic thrombophilia in Korea are different not only from those in Caucasians but also those in other Asian populations.

Protein C

Protein C (PC) is a 62-kDa vitamin K-dependent plasma zymogen which, after activation to serine protease, plays an important role in the physiologic regulation of blood coagulation. Given that PC is one of the major naturally occurring inhibitors of coagulation, acquired or hereditary deficiencies of this protein result in excessive thrombin generation. As a vast array of mutations are responsible for hereditary PC deficiencies, screening for their presence by DNA testing would require sequencing each entire gene involving numerous exons. Moreover, the knowledge of the gene mutation does not offer any benefit in the treatment of thrombophilic families, so the routine molecular characterization is not indicative. These defects are detected by functional or immunological assays. Measurement of PC activity is essential to identify subjects with both type I and type II PC defects. There is no need to routinely perform PC immunological assays. However, they are useful in order to distinguish type I from type II PC hereditary deficiency.

Protein S

Protein S (PS) is a vitamin K-dependent plasma glycoprotein. Around 60-70% of PS in plasma is noncovalently bound to C4-binding protein (C4BP). Free PS functions as a cofactor that enhances the activity of activated protein C (APC) in the proteolytic degradation of activated factors V and VIII. PS also has a more recently described APC-independent ability to directly inhibit prothrombinase and tenase by direct binding of activated factors V, VIII, and X. Given that PS is one of the major naturally occurring inhibitors of coagulation, acquired or hereditary deficiencies of this protein result in excessive thrombin generation. As a vast array of mutations are responsible for hereditary PS deficiencies, screening for their presence by DNA testing would require sequencing each entire gene involving numerous exons. Moreover, the knowledge of the gene mutation does not offer any benefit in the treatment of thrombophilic families, so the routine molecular characterization is not indicative. These defects are detected by functional or immunological assays for free and total PS forms. Given that functional PS assays may detect some forms of PS deficiency that free PS immunoassays may miss, it is recommended to include them for initial testing along with immunoassays for free PS, although they should be used with caution. Functional PS assays are subject to multiple interference. For example in the presence of lupus anticoagulant (LA), only free PS immunoassays are recommended for initial testing. PS antigen assays are more popular with most laboratories.

Biomarker response to drotrecogin alfa (activated) in children with severe sepsis: results from the RESOLVE clinical trial*

OBJECTIVE

REsearching severe Sepsis and Organ dysfunction in children: A gLobal perspective (RESOLVE), a phase III trial of drotrecogin alfa (activated) in pediatric severe sepsis, examined biomarker changes in inflammation and coagulation. This report describes biomarker profiles in early severe sepsis and the pharmacodynamic assessment of drotrecogin alfa (activated) in RESOLVE.

DESIGN

Serial measurements of interleukin-1β, interleukin-6, interleukin-8, interleukin-10, tissue necrosis factor-α, procalcitonin, D-dimer, and thrombin-antithrombin complex were performed at baseline and daily over the first five study days. Protein C levels were performed at baseline and at the end of the 96-hr study drug infusion. Analysis of variance-based log-transformed data compared the treatment groups for each measured variable.

SETTING

: One hundred four pediatric intensive care units in 18 countries.

PATIENTS

Four hundred seventy-seven children between 38 wks corrected gestational age and 17 yrs with sepsis-induced cardiovascular and respiratory dysfunction.

INTERVENTIONS

Drotrecogin alfa (activated).

MEASUREMENTS AND MAIN RESULTS

Pharmacodynamic activity of drotrecogin alfa (activated) compared with placebo was observed with reduction of D-dimer on day 1 (p < .01) and thrombin-antithrombin complex on days 1-4 (p < .05). There were no significant changes by treatment in multiple cytokines or procalcitonin. In the overall population, a median protein C difference was not observed (p > .05) with drotrecogin alfa (activated) administration compared with placebo, although a difference (median percentage change from baseline) in favor of drotrecogin alfa (activated) was observed in patients >1 yr old (p = .0449).

CONCLUSIONS

While children in the RESOLVE trial were similar to adults in that they showed a relationship between severity of coagulation and inflammation abnormalities and mortality, their pharmacodynamic response to drotrecogin alfa (activated) differed with respect to changes in protein C activity and systemic inflammation.

Deficiencies of antithrombin, protein C and protein S - practical experience in genetic analysis of a large patient cohort

Deficiencies of natural anticoagulant proteins including antithrombin (AT), protein C (PC) and protein S (PS) are important causes of inherited thrombophilia. This study aimed to report on the practical experience gained in performing genetic analyses of a large cohort of patients with AT, PC and PS deficiencies and to relate this knowledge to clinical application. We genotyped a large cohort of 709 unrelated patients with AT (231), PC (234) and PS (244) deficiencies referred to us by physicians throughout Germany. Mutations were detected by direct sequencing and multiplex ligation-dependent probe amplification (MLPA). The highest mutation detection rate (MDR) was found for the SERPINC1 gene (83.5%), followed by the PROC (69%) and PROS1 (43%) genes. Even at AT activities close to the normal range (75%), the MDR was 70%. Contrastingly, for PC and PS deficiencies, the MDR dropped significantly and mildly lowered to subnormal values. At PS activities >55% for PS no mutations were detected. Mutation profiles of all three genes were similar with the highest prevalence for missense mutations (63-78%), followed by nonsense (7-11%), splice-site mutations (7-13%), small deletions (1-8%), small insertions/duplications (1-4%) and large deletions (3-6%). In conclusion, genetic testing is a useful diagnostic tool for diagnosing thrombophilia. Based on our data, genetic analysis for patients with AT deficiency is indicated for all subnormal activities. In contrast, genotyping is not advisable for PC activities >70% and for PS activities >55%.

Protein C, protein S and von Willebrand factor levels correlate with bleeding symptoms: a population-based study

Although natural anticoagulant deficiencies are the established causes of thrombosis, their roles in bleeding are not fully studied. The objective is to correlate haemostatic factors with haemorrhagic symptoms quantified by a standardized questionnaire. Adult subjects were recruited from Bangkok and nearby provinces as part of routine health surveys/checkups. The validated MCMDM-1VWD form was used to assess their bleeding symptoms. At the same time, von Willebrand factor (VWF) activity, free protein S levels and protein C activity were measured. There were 5196 individuals. The mean age was 44.3 years (range 15-99) and 41% were male subjects. The mean bleeding score was -0.28 and 95% of subjects had scores between -2 and +2. The scores were lower in female subjects than in male subjects (-0.35 vs. -0.16, P < 0.001). Bleeding scores correlated negatively with age, VWF and protein C activities (Spearman's ρ-0.258, -0.091 and -0.098, respectively, all P < 0.001), but did not significantly correlate with protein S levels. Using multivariate analysis, female gender, VWF below 100 IU dL(-1), protein C below 100 IU dL(-1) and protein S over 150 IU dL(-1) significantly related to high (≥3) bleeding scores (adjusted odds ratio 1.95, 1.83, 1.56 and 2.84, P = 0.001, 0.001, 0.039 and 0.017, respectively). These findings may suggest interacting roles of VWF and natural anticoagulants in modifying bleeding symptoms.

Protein C activity in dogs: adaptation of a commercial human colorimetric assay and evaluation of effects of storage time and temperature

Objectives of this study were to adapt a commercial human protein C (PC) colorimetric assay for use in dogs and to investigate effects of various storage conditions. The human assay was modified by using pooled canine plasma for calibration and by increasing the activation time. PC activity was measured in fresh canine plasma and in plasma stored under various conditions. PC activity of some stored samples was significantly different from that of fresh plasma; however, differences were small. No difference was detected in samples stored under similar conditions but analyzed in different laboratories using similar methodology. Results of this study indicate that the human colorimetric assay is suitable for canine samples if pooled canine plasma is used for calibration, that Clinical and Laboratory Standards Institute sample storage guidelines developed for testing in humans are appropriate for dogs, and that comparisons of results from laboratories using similar methodology are legitimate.

External Quality Assurance of Antithrombin, Protein C, and Protein S Assays: Results of the College of American Pathologists Proficiency Testing Program in Thrombophilia

Context.—Hereditary and acquired deficiencies of antithrombin (AT), protein C (PC), and protein S (PS) are risk factors for venous thromboembolism. Proper diagnosis requires high-quality assays for these proteins.

Objective.—To determine the accuracy and interlaboratory precision of AT, PC, and PS assays used by laboratories participating in the United States College of American Pathologists proficiency testing program in thrombophilia and to grade the performance of laboratories.

Design.—Standardized normal plasma with assigned analyte values was sent in 2 separate challenges to participating laboratories. Participants measured AT, PC, and PS levels using local methods.

Results.—When compared with the assigned values for the international standard, the order of assay accuracy from highest to lowest was AT activity, PC antigen, AT antigen, total PS antigen, PC activity, PS activity, and free PS antigen (range of assay bias, 2.6%–8.8%). The order of assay precision from highest to lowest was PC activity, AT activity, AT antigen, total PS antigen, PS activity, free PS antigen, and PC antigen (range of assay coefficient of variation, 6.1%–20.0%). Most testing events (87.8%) could be graded as pass or fail using a target range of ±3 standard deviations from the method-specific mean. The pass rate was 98.2% for all AT, PC, and PS testing events combined.

Conclusions.—Accuracy and precision were higher for AT assays and lower for PC and PS assays. It was feasible to grade individual laboratory performance.

Functional protein C levels during the early phase of clinical acute pancreatitis

OBJECTIVE

Protein C modulates microvascular thrombosis in sepsis, with levels being depleted in severe cases. Similar changes occur in necrotizing acute pancreatitis (AP). However, little is known of the pathophysiological characteristics of endogenous protein C early in the disease course of AP. This study undertakes an evaluation of protein C levels in AP.

METHODS

In a consecutive series of 57 patients with AP, the chromogenic substrate method was used to determine functional protein C levels in plasma. Protein C activity and variables required for the calculation of Acute Physiology and Chronic Health Evaluation II (APACHE II) scores were assessed at admission and 24 and 48 hours after admission.

RESULTS

The median functional protein C level was 97 U/dL (range, 41-178 U/dL) on admission and 96 U/dL (range, 46-170 U/dL) 24 hours after admission. There was no significant difference in the functional protein C levels between the patients with an admission APACHE score of 8 or higher and those with lower APACHE II scores. Linear regression plots showed a nonsignificant trend to the lower levels of functional protein C activity in those patients with higher APACHE II scores.

CONCLUSIONS

In human AP, functional protein C levels are conserved in mild disease. However, there is evidence that levels are depleted early in severe disease, suggesting a parallel between the pathophysiology of severe sepsis and that of severe AP.

Laboratory tests for protein C deficiency

Hereditary protein C deficiency is a hypercoagulable state associated with an increased risk for venous thrombosis. The recommended initial test for protein C is an activity (functional) assay, which may be clotting time based or chromogenic. The advantages and disadvantages of the various testing options are presented. The causes of acquired protein C deficiency are much more common than hereditary deficiency. Therefore, this article describes the appropriate steps to take when protein C activity is low, to confirm or exclude a hereditary deficiency. The causes of falsely normal results are also described, including lupus anticoagulants and direct thrombin inhibitors.

Pesquisa de marcadores de trombofilia em eventos trombóticos arteriais e venosos: registro de 6 anos de investigação

CONTEXTO: Os autores apresentam uma análise epidemiológica sobre a investigação de marcadores de trombofilia em pacientes que apresentaram eventos trombóticos arteriais e/ou venosos acompanhados no Departamento de Angiologia e de Cirurgia Vascular do CENTERVASC no período de janeiro de 2001 a janeiro de 2007. OBJETIVO: Avaliar a prevalência de marcadores de trombofilias congênitas ou adquiridas nos eventos trombóticos venosos e/ou arteriais. MÉTODOS: Entre janeiro de 2001 e janeiro de 2007, 224 pacientes com eventos trombóticos venosos e/ou arteriais foram submetidos a uma rotina de investigação quanto à presença ou não de marcadores de trombofilia, independentemente da idade e história familiar dos pacientes, topografia do evento e presença ou ausência de fatores trombogênicos extrínsecos. RESULTADOS: Foram detectados marcadores de trombofilia em 112 pacientes (50% dos casos). Nestes, observou-se de modo predominante a positividade para anticorpos antifosfolipídios, anticardiolipina e/ou anticoagulante lúpico (39 casos), bem como a presença do fator V de Leiden (43 casos). O sistema venoso foi significativamente o mais acometido, e a ocorrência associada com condições trombogênicas extrínsecas esteve presente em 56 (50%) dos portadores de marcadores de trombofilias. CONCLUSÕES: A presença de marcadores de trombofilia nos pacientes com eventos trombóticos, venosos e/ou arteriais, independentemente da faixa etária ou da existência de fatores extrínsecos associados, foi significativa.

Testing for hereditary thrombophilia: a retrospective analysis of testing referred to a national laboratory

Background

Predisposition to venous thrombosis may be assessed through testing for defects and/or deficiencies of a number of hereditary factors. There is potential for confusion about which of these tests are appropriate in which settings. At least one set of recommendations has been published to guide such testing, but it is unclear how widely these have been disseminated.

Methods

We performed a retrospective analysis of laboratory orders and results at a national referral laboratory to gain insight into physicians' ordering practices, specifically comparing them against the ordering practices recommended by a 2002 College of American Pathologists (CAP) consensus conference on thrombophilia testing. Measurements included absolute and relative ordering volumes and positivity rates from approximately 200,000 thrombophilia tests performed from September 2005 through August 2006 at a national reference laboratory. Quality control data were used to estimate the proportion of samples that may have been affected by anticoagulant therapy. A sample of ordering laboratories was surveyed in order to assess potential measurement bias.

Results

Total antigen assays for protein C, protein S and antithrombin were ordered almost as frequently as functional assays for these analytes. The DNA test for factor V Leiden was ordered much more often than the corresponding functional assay. In addition, relative positivity rates coupled with elevations in prothrombin time (PT) in many of these patients suggest that these tests are often ordered in the setting of oral anticoagulant therapy.

Conclusion

In this real-world setting, testing for inherited thrombophilia is frequently at odds with the recommendations of the CAP consensus conference. There is a need for wider dissemination of concise thrombophilia testing guidelines.

Inherited Thrombophilia: Key Points for Genetic Counseling

With the evolution of medical genetics to focus on highly prevalent, multifactorial conditions, it is inevitable that genetic counselors will be called upon to participate in the evaluation and counseling of individuals with inherited thrombophilia. The purpose of this review is to educate the genetic counselor on key issues related to risk assessment and genetic counseling for hereditary thrombophilia. The information contained in this document is derived from an extensive review of the literature, as well as the author's personal expertise. Upon completion of this review, the genetic counselor will be able to: a) describe inherited and acquired risk factors for thrombosis, b) collect and interpret personal and family histories to assess risk related to hereditary thrombophilia, c) discuss the potential advantages and disadvantages of thrombophilia testing, including psychosocial aspects and implications for medical management, and d) identify educational and support resources for patients and families.

Evaluation of plasma protein C activity for detection of hepatobiliary disease and portosystemic shunting in dogs

OBJECTIVE

To determine the diagnostic value of protein C (PC) for detecting hepatobiliary disease and portosystemic shunting (PSS) in dogs.

DESIGN

Prospective study.

ANIMALS

238 clinically ill dogs with (n = 207) and without (31) hepatobiliary disease, including 105 with and 102 without PSS.

PROCEDURES

Enrollment required routine hematologic, serum biochemical, and urine tests; measurement of PC activity; and a definitive diagnosis. Total serum bile acids (TSBA) concentration and coagulation status, including antithrombin activity, were determined in most dogs. Dogs were grouped into hepatobiliary and PSS categories. Specificity and sensitivity were calculated by use of a PC cutoff value of 70% activity.

RESULTS

Specificity for PC activity and TSBA concentrations was similar (76% and 78%, respectively). Best overall sensitivity was detected with TSBA, but PC activity had high sensitivity for detecting PSS and hepatic failure. Protein C activity in microvascular dysplasia (MVD; PC > or = 70% in 95% of dogs) helped differentiate MVD from portosystemic vascular anomalies (PSVA; PC < 70% in 88% of dogs). A receiver operating characteristic curve (PSVA vs MVD) validated a useful cutoff value of < 70% activity for PC.

CONCLUSIONS AND CLINICAL RELEVANCE

Combining PC with routine tests improved recognition of PSS, hepatic failure, and severe hepatobiliary disease and signified a grave prognosis when coupled with hyperbilirubinemia and low antithrombin activity in hepatic failure. Protein C activity can help prioritize tests used to distinguish PSVA from MVD and sensitively reflects improved hepatic-portal perfusion after PSVA ligation.

Etiology and consequences of thrombosis in abdominal vessels

The thrombophilia which can be either congenital or acquired in adult life has major implications in the abdominal vessels. The resulting portal vein thrombosis, Budd-Chiari syndrome and mesenteric vein thrombosis have a variety of consequences ranging from acute abdomen to chronic hepatomegaly and even totally asymptomatic patient in whom the only finding is pancytopenia. The complications like esophageal varices, portal gastropathy, ascites, severe hypersplenism, liver failure requiring liver transplantation are well known. Interesting features of collateral venous circulation showing itself as pseudocholangiocarcinoma sign and its possible clinical reflection as cholestasis are also known from a long time. The management strategies for these complications of intraabdominal vessel thrombosis are not different from their counterpart which is cirrhotic portal hypertension, but the prognosis is unquestionably better in former cases. In this review we presented and discussed the abdominal venous thrombosis, etiology and the resulting clinical pictures. There are controversial issues both in nomenclature, and management including anticoagulation problems and follow up strategies. In light of the current knowledge, we discussed some controversial issues in literature and presented our experience and our proposals about this group of patients.

Thrombophilien bei Patienten mit isch�mischem Schlaganfall

Patients with ischemic stroke are sometimes found to have an underlying inherited (deficiency of protein C, protein S, antithrombin III, activated protein C resistance, prothrombin gene mutation, hyperhomocysteinemia) or acquired thrombophilia (lupus anticoagulant and anticardiolipin antibodies, hyperhomocysteinemia). Patient selection for thrombophilia screening is, therefore, a frequent question in managing patients with ischemic stroke. In this review we discuss patient selection and timing for laboratory tests for thrombophilia screening in stroke patients based on a literature review and we calculated overall costs per year in Germany for testing patients older than 18 years with an ischemic stroke of undetermined cause. As there is a lack of studies comparing anticoagulation with antiplatelet therapy in patients with diagnosed thrombophilia, laboratory screening for thrombophilia even in a selected group of patients with cryptogenic ischemic stroke remains of questionable value at present. An exception appears to be testing for lupus anticoagulant and anticardiolipin antibodies in younger patients with suspected antiphospholipid syndrome (two positive test results necessary), because anticoagulation seems to be superior to aspirin in patients with antiphospholipid syndrome.

Results of a Survey of Hospital Coagulation Laboratories in the United States, 2001

Context.—Coagulation and bleeding problems are associated with substantial morbidity and mortality, and inappropriate testing practices may lead to bleeding or thrombotic complications.

Objective.—To evaluate practices reported by hospital coagulation laboratories in the United States and to determine if the number of beds in a hospital was associated with different practices.

Design.—From a sampling frame of institutions listed in the 1999 directory of the American Hospital Association, stratified into hospitals with 200 or more beds (“large hospitals”) and those with fewer than 200 beds (“small hospitals”), we randomly selected 425 large hospitals (sampling rate, 25.6%) and 375 small hospitals (sampling rate, 8.8%) and sent a survey to them between June and October 2001. Of these, 321 large hospitals (75.5%) and 311 small hospitals (82.9%) responded.

Results.—An estimated 97.1% of respondents reported performing some coagulation laboratory tests. Of these, 71.6% reported using 3.2% sodium citrate as the specimen anticoagulant to determine prothrombin time (81.3% of large vs 67.7% of small hospitals, P &lt; .001). Of the same respondents, 45.3% reported selecting thromboplastins insensitive to heparin in the therapeutic range when measuring prothrombin time (59.4% of large vs 39.8% of small hospitals, P &lt; .001), and 58.8% reported having a therapeutic range for heparin (72.9% of large vs 53.2% of small hospitals, P &lt; .001). An estimated 96.3% of respondents assayed specimens for activated partial thromboplastin time within 4 hours after phlebotomy, and 89.4% of respondents centrifuged specimens within 1 hour of collection. An estimated 12.1% reported monitoring low-molecular-weight heparin therapy, and to do so, 79% used an assay for activated partial thromboplastin time (58% of large vs 96% of small hospitals, P = .001), whereas 38% used an antifactor Xa assay (65% of large vs 18% of small hospitals, P = .001).

Conclusions.—Substantial variability in certain laboratory practices was evident. Where significant differences existed between the hospital groups, usually large hospitals adhered to accepted practice guidelines to a greater extent. Some reported practices are not consistent with current recommendations, showing a need to understand the reasons for noncompliance so that better adherence to accepted standards of laboratory practice can be promoted.

Genetic thrombophilia

The genetic thrombophilias are an important cause of venous thrombotic events. Much has been learned about the natural history of these disorders, their genetics, and, to a lesser degree, their treatment. This article provides an overview of the genetics of thrombophilia. Specific information on the factor V Leiden mutation;the prothrombin G20210A mutation; and protein C, proteinS, and antithrombin deficiency is reviewed. Current testing and treatment options for the genetic thrombophilias also are discussed.

College of American Pathologists Consensus Conference XXXVI: Diagnostic Issues in Thrombophilia

OBJECTIVES

To review the state of the art relating to laboratory testing for thrombophilia, as reflected by the medical literature and the consensus opinion of recognized experts in the field, and to make recommendations regarding laboratory testing (whom to test, when to test, what tests to perform, rationale for testing, and other issues) in the assessment of thrombotic risk in individual patients and their family members.

DATA SOURCES

Review of the medical literature (primarily from the last 10 years) and the experience and opinions of experts in the field were used as data sources.

DATA EXTRACTION AND SYNTHESIS

Participating authors evaluated the medical literature and prepared manuscripts with specific proposed recommendations. Drafts of all of the manuscripts were prepared and circulated to every participant in the College of American Pathologists Conference XXXVI: Diagnostic Issues in Thrombophilia prior to the conference. Each of the conclusions and associated recommendations was then presented for discussion. Recommendations were accepted if a consensus of 70% or more of the 27 experts attending the conference was reached. The results of the discussion were then used to revise the manuscripts and recommendations into final form.

CONCLUSIONS

Consensus was reached on 179 recommendations, all of which are presented in articles in this issue of the Archives. Detailed discussion of the rationale for each of these recommendations is found in the text of the respective articles, along with citations to justify the level of evidence for the recommendations. This is an evolving area of research, and it is certain that further clinical studies will change many of the recommendations, cause some to be deleted, and add others in the future.