Persistent post-splenectomy thrombocytosis and thrombo-embolism: a consequence of continuing anaemia

Impact of HbE mutation on the clinical severity of HbH disease: A multicentre study from Thailand

Haemoglobin (Hb) H disease and HbH disease with co-inherited HbE mutation are the most prevalent forms of α-thalassaemia in Southeast Asia. Data were limited when comparing clinical phenotypes between these two patient groups. We conducted a Thai multicentre study and enrolled 588 patients [median (IQR) age 13.0 (6.7-20.3) years], including those with deletional HbH disease with (n = 47) and without (n = 187) co-inherited HbE mutation and non-deletional HbH disease with (n = 101) and without (n = 253) co-inherited HbE mutation. Patients with HbH disease with co-inherited HbE mutation suffered more severe manifestations than those without. This observation was more pronounced in patients with non-deletional HbH disease. A greater proportion of patients with non-deletional HbH disease with co-inherited HbE mutation (43.6%) eventually required regular transfusions compared to those without (30.4%, p = 0.019). Among those with non-deletional HbH disease who did not require regular transfusions, Hb levels were lower in patients with co-inherited HbE mutation [8.1 (7.2-8.6) vs. 8.8 (8.2-9.5) g/dL, p < 0.001]. Among patients requiring regular transfusions who underwent splenectomy, 11/12 patients with non-deletional HbH disease stopped transfusion compared with 1/3 in non-deletional HbH disease with co-inherited HbE mutation group (p = 0.024). These findings provide insights for the clinical monitoring and management of HbH disease in the region.

Αlpha-thalassemia: A practical overview

α-Thalassemia is an inherited blood disorder characterized by decreased synthesis of α-globin chains that results in an imbalance of α and β globin and thus varying degrees of ineffective erythropoiesis, decreased red blood cell (RBC) survival, chronic hemolytic anemia, and subsequent comorbidities. Clinical presentation varies depending on the genotype, ranging from a silent or mild carrier state to severe, transfusion-dependent or lethal disease. Management of patients with α-thalassemia is primarily supportive, addressing either symptoms (eg, RBC transfusions for anemia), complications of the disease, or its transfusion-dependence (eg, chelation therapy for iron overload). Several novel therapies are also in development, including curative gene manipulation techniques and disease modifying agents that target ineffective erythropoiesis and chronic hemolytic anemia. This review of α-thalassemia and its various manifestations provides practical information for clinicians who practice beyond those regions where it is found with high frequency.

Venous Thromboembolism in Special Populations: Preexisting Cardiopulmonary Disease, Cirrhosis, End-Stage Renal Disease, and Asplenia

Venous thromboembolism (VTE) is a common cause of morbidity and mortality. Presence of preexisting conditions, such as cardiopulmonary diseases, cirrhosis, renal dysfunction, and asplenia, commonly occurs in VTE patients. Moreover, these conditions often are risk factors for developing VTE. These preexisting conditions make VTE diagnosis and treatment challenging and worsen outcomes. Current guidelines do not include detailed features in the diagnosis and management of patients with preexisting conditions. This review discusses presence of VTE in patients with preexisting cardiopulmonary diseases, cirrhosis, renal dysfunction, and asplenia.

A Case of Cavernous Haemangioma of the Spleen

The clinical and pathological data of a case of cavernous haemangioma of the spleen are reported. The diagnostic value of scanning in the present case is discussed.

Non syndromic childhood onset congenital sideroblastic anemia: A report of 13 patients identified with an ALAS2 or SLC25A38 mutation

The most frequent germline mutations responsible for non syndromic congenital sideroblastic anemia are identified in ALAS2 and SLC25A38 genes. Iron overload is a key issue and optimal chelation therapy should be used to limit its adverse effects on the development of children. Our multicentre retrospective descriptive study compared the strategies for diagnosis and management of congenital sideroblastic anemia during the follow-up of six patients with an ALAS2 mutation and seven patients with an SLC25A38 mutation. We described in depth the clinical, biological and radiological phenotype of these patients at diagnosis and during follow-up and highlighted our results with a review of available evidence and data on the management strategies for congenital sideroblastic anemia. This report confirms the considerable variability in manifestations among patients with ALAS2 or SLC25A38 mutations and draws attention to differences in the assessment and the monitoring of iron overload and its complications. The use of an international registry would certainly help defining recommendations for the management of these rare disorders to improve patient outcome.

Fatal pulmonary embolism following splenectomy in a patient with Evan's syndrome: case report and review of the literature

Background

Evans syndrome (ES) is a rare disease characterized by simultaneous or sequential development of autoimmune hemolytic anemia (AIHA) and immune thrombocytopenia (ITP) with or without immune neutropenia. Splenectomy is one of the treatment options for disease refractory to medical therapy. Venous thromboembolism (VTE) following splenectomy for hematological diseases has an incidence of 10%.

Case presentation

Here we describe a case report of a young patient hospitalized with severe hemolytic anemia with Hgb 4.8 g/dl. He developed thrombocytopenia with platelet nadir of 52,000/mm³, thus formally diagnosed with ES. He failed standard medical therapy. He underwent splenectomy and had a fatal outcome. Autopsy confirmed the cause of death as pulmonary embolism (PE).

Conclusions

This case report and review of the literature highlight important aspects of the association between VTE, splenectomy, and hemolytic syndromes including the presence of thrombocytopenia. The burden of the disease is reviewed as well as various pathophysiologic mechanisms contributing to thromboembolic events in these patients and current perioperative prophylactic anticoagulation strategies. Despite an advancing body of literature increasing awareness of VTE following splenectomy, morbidity and mortality remains high. Identifying high risk individuals for thromboembolic complications from splenectomy remains a challenge. There are no consensus guidelines for proper perioperative and post-operative anti-coagulation. We encourage future research to determine which factors might be playing a role in increasing the risk for VTE in real time with hope of forming a consensus to guide management.

Spinal Cord Infarction in a Patient with Hereditary Spherocytosis: A Case Report and Discussion

The etiology of spinal cord infarcts (SCIs), besides being related to aortic perioperative events, in large subset of SCIs, remains cryptogenic. We present a first case of SCI in a patient with hereditary spherocytosis and discuss the potential pathophysiologic considerations for vascular compromise. A 43-year-old woman with a history of hereditary spherocytosis, post splenectomy status, presented with chest, back, and shoulder pain with subsequent myelopathic picture; SCI extending from C4-T2 was confirmed by MRI. Despite aggressive treatment her stroke progressed leading to her demise. Her autopsy confirmed the SCI and revealed some incidental findings, but the cause of SCI remained unidentified. Exclusion of the known etiologies of SCI by extensive negative workup including autopsy evaluation suggested that SCI in our case was related to her history of hereditary spherocytosis. Both venous and arterial adverse vascular events, at a higher rate, have been associated in patients with hereditary spherocytosis who had their spleens removed compared to nonsplenectomized patients. Postsplenectomy increases in the platelet, red blood cell count, leukocyte count, and cholesterol concentrations are postulated to contribute to increased thrombotic risk. Additional prothrombotic factors include continuous platelet activation and adhesion as well as abnormalities of the red blood cell membrane.

Persistent thrombocytopaenia in a young man with splenomegaly, rebound thrombocytosis after splenectomy and subsequent pulmonary embolism: splenic littoral cell angioma and associated events

Littoral cell angioma (LCA) is a rare endothelial cell neoplasm in the spleen. Although many cases of LCA are asymptomatic, some present with signs and symptoms related to splenomegaly, whereas others manifest with haematological abnormalities, including anaemia and/or thrombocytopaenia (ie, hypersplenism). We report a case of LCA presenting with chronic thrombocytopaenia, probably due to splenic sequestration of platelets or phagocytosis of platelets by neoplastic cells. Following therapeutic splenectomy, the patient suffered from a marked rebound thrombocytosis and subsequently developed pulmonary embolisms. He was treated with anticoagulant therapy combined with antiplatelet therapy, and his symptoms were quickly resolved. This case emphasises an exclusion of primary splenic disorders in patients with chronic thrombocytopaenia, especially in those with splenomegaly and the contemplation of thromboembolism prophylaxis postsplenectomy.

Splenectomy is associated with a higher risk for venous thromboembolism: A prospective cohort study

BACKGROUND

Thrombocytosis following splenectomy is a common occurrence. Whether this thrombocytosis leads to a higher risk for venous thromboembolism (VTE) remains unclear. This investigation aimed to determine if splenectomy increases the risk for VTE.

METHODS

This was a prospective study conducted in the SICU between 1/2011 and 11/2013 investigating the VTE risk in patients undergoing a splenectomy compared with those undergoing any other abdominal procedure.

RESULTS

In total 2503 patients were admitted to the SICU: 37 (2%) after a splenectomy and 638 (26%) after any other abdominal surgery. Splenectomy patients had a higher incidence of VTE compared to patients undergoing any other abdominal procedure (29.7% vs. 12.1%, p < 0.01). After adjustment, splenectomy was associated with a higher adjusted risk for VTE compared to the no-splenectomy group (AOR [95% CI]: 2.6 [1.2, 5.9], p = 0.02). Reactive thrombocytosis did not predict the development of VTE.

CONCLUSION

Splenectomy increases the risk for VTE, however reactive thrombocytosis is not associated with this higher incidence. Further investigations are required to characterize the pathophysiologic mechanisms of VTE development following splenectomy.

Splenectomy complicated by sustained extreme thrombocytosis and extensive portosplenomesenteric vein thrombosis in pyrimidine 5'-nucleotidase deficiency

Reactive and redistributional thrombocytosis is a well-known postsplenectomy occurrence .Usually it is transient and it rarely reaches extreme levels. We report a rare case of haemolytic anaemia where splenectomy was carried out following trauma to a massively enlarged spleen and was followed by extreme sustained thrombocytosis associated with extensive portal, splenic and mesenteric vein thrombosis despite standard antithrombotic prophylaxis.

Long-term risks after splenectomy among 8,149 cancer-free American veterans: a cohort study with up to 27 years follow-up

Although preservation of the spleen following abdominal trauma and spleen-preserving surgical procedures have become gold standards, about 22,000 splenectomies are still conducted annually in the USA. Infections, mostly by encapsulated organisms, are the most well-known complications following splenectomy. Recently, thrombosis and cancer have become recognized as potential adverse outcomes post-splenectomy. Among more than 4 million hospitalized USA veterans, we assessed incidence and mortality due to infections, thromboembolism, and cancer including 8,149 cancer-free veterans who underwent splenectomy with a follow-up of up to 27 years. Relative risk estimates and 95% confidence intervals were calculated using time-dependent Poisson regression methods for cohort data. Splenectomized patients had an increased risk of being hospitalized for pneumonia, meningitis, and septicemia (rate ratios=1.9-3.4); deep venous thrombosis and pulmonary embolism (rate ratios=2.2); certain solid tumors: buccal, esophagus, liver, colon, pancreas, lung, and prostate (rate ratios =1.3-1.9); and hematologic malignancies: non-Hodgkin lymphoma, Hodgkin lymphoma, multiple myeloma, acute myeloid leukemia, chronic lymphocytic leukemia, chronic myeloid leukemia, and any leukemia (rate ratios =1.8-6.0). They also had an increased risk of death due to pneumonia and septicemia (rate ratios =1.6-3.0); pulmonary embolism and coronary artery disease (rate ratios =1.4-4.5); any cancer: liver, pancreas, and lung cancer, non-Hodgkin lymphoma, Hodgkin lymphoma, and any leukemia (rate ratios =1.3-4.7). Many of the observed risks were increased more than 10 years after splenectomy. Our results underscore the importance of vaccination, surveillance, and thromboprophylaxis after splenectomy.

Advances in the treatment of alpha-thalassemia

Alpha (α)-thalassemia represents a group of recessively inherited hemoglobin disorders marked by deficient or absent synthesis of 1 to all 4 of the α-globin genes. Inactivation of 3 α-globin genes--either by deletional or nondeletional mutations--results in hemoglobin H (Hb H) disease. Patients with Hb H disease produce hemoglobin composed of all beta chains and have moderate to severe hemolytic anemia, a variable degree of ineffective erythropoiesis, and splenomegaly. Transfusion requirements vary depending on the mutation and clinical severity. Treatment for deletional Hb H disease is primarily preventative and transfusions are uncommon. Patients with nondeletional Hb H disease (e.g., Hb H Constant Spring) typically have more severe anemia, and approximately one-third require regular transfusions. These patients often require comprehensive, multidisciplinary care. This chapter focuses on screening, diagnosis, and treatment approaches for patients with Hb H disease.

Postsplenectomy reactive thrombocytosis

Thrombocytosis is frequently encountered as an incidental laboratory finding. The most common etiology is reactive (secondary) thrombocytosis due to infections, trauma, surgery, or occult malignancy. Even though thrombocytosis is benign and self-limiting in most cases, it can result in hemorrhage or thrombosis. The hypercoagulable state is characterized by episodes of thrombosis and can be due to inherited or acquired conditions. Extreme thrombocytosis may result in thrombotic events such as acute myocardial infarction, mesenteric vein thrombosis, and pulmonary embolism. It is important for physicians to be familiar with the complications associated with thrombocytosis. Postsplenectomy reactive thrombocytosis has an incidence of about 75% to 82%. Thrombosis in association with elevated platelet count after splenectomy is well recognized, with an incidence of approximately 5%. This case report describes a 61-year-old patient who underwent emergent splenectomy and presented 1 week later with acute ST segment elevation myocardial infarction. Severe thrombocytosis, which was not present prior to splenectomy, was noted, and a diagnosis of reactive thrombocytosis was initially made. Involvement of the right coronary artery led to emergent percutaneous transluminal coronary angioplasty. Essential thrombocytosis was considered when treatment with hydroxyurea failed to lower the platelet count. A review of arterial and venous thrombosis in patients with severe thrombocytosis is presented, and the approach to the management of such patients is discussed.

Absence of JAK2V617F mutation in patients with beta-thalassemia major and thrombocytosis due to splenectomy

The report of Janus Kinase 2 (JAK2) mutations in myeloid malignancies with high frequency in myeloproliferative neoplasms has been well known since 2005. By monitoring allele burden, it is found that the expression of JAK2V617F mutation is increasing significantly from essential thrombocytosis to polycythemia vera. Furthermore, JAK2 abnormalities are reported in the majority of unexplained thrombotic episodes. Thalassemic syndromes are characterized by ineffective erythropoiesis and thrombocytosis, mainly due to splenectomy. The high incidence of thromboembolic events has led to the identification of a prothrombotic state in these patients. The contribution of JAK2 mutations to the hypercoagulable state of thalassemic patients is still unknown. Furthermore, the potential role of Janus Kinase mutations in hepcidin expression and consequently in ineffective erythropoiesis is still under investigation. This study was scheduled to determine whether the presence of JAK2V617F mutation in thalassemic patients is associated with thrombocytosis. We studied 20 patients DNA with beta-thalassemia for JAK2V617F mutation by using RG-PCR method. None of the patients were positive for this particular mutation. More studies are needed to prove the role of JAK2 in ineffective erythropoiesis, iron metabolism and thrombocytosis and to determine if using JAK2 inhibitors in thalassemic patients can be a potential therapeutic option.

Guidelines for the diagnosis and management of hereditary spherocytosis--2011 update

Guidelines on hereditary spherocytosis (HS) published in 2004 (Bolton-Maggs et al, 2004) are here replaced to reflect changes in current opinion on the surgical management, (particularly the indications for concomitant splenectomy with cholecystectomy in children with mild HS, and concomitant cholecystectomy with splenectomy in those with asymptomatic gallstones). Further potential long term hazards of splenectomy are now recognised. Advances have been made in our understanding of the biochemistry of the red cell membrane which underpins the choice of tests. Biochemical assays of membranes proteins and genetic analysis may be indicated (rarely) to diagnose atypical cases. The diagnostic value of the eosin-5-maleimide (EMA) binding test has been validated in a number of studies with understanding of its limitations.

Traditional laboratory measures of cardiovascular risk in hereditary spherocytosis

BACKGROUND

Individuals who have undergone splenectomy may be at an increased risk of arterial and venous thrombosis. We sought to determine if splenectomy affects surrogate laboratory measures of cardiovascular risk in persons with hereditary spherocytosis (HS).

PROCEDURE

We conducted a prospective cross-sectional study of 21 children and 36 adults with HS. Fasting blood samples were collected for complete blood count and plasma lipid panel, homocysteine, lipoprotein (a), C-reactive protein, and fibrinogen. The variables were compared between the groups with and without prior splenectomy by Mann-Whitney tests.

RESULTS

Subjects with prior splenectomy had higher hemoglobin, white blood cell and platelet counts and lower reticulocyte counts and total serum bilirubin concentrations (P < 0.001). Subjects not having had splenectomy had lower than normal levels of total and LDL-cholesterol (LDL-C). Total and LDL-C values were significantly higher, as were fibrinogen and homocysteine concentrations, in the post-splenectomy subjects than in individuals with intact spleen.

CONCLUSION

Various lipid levels and other measures of cardiovascular risk are affected by splenectomy in persons with HS. Further investigations are indicated to more clearly define the balance of the potential benefits of hemolysis and anemia versus the deleterious effects of splenectomy in HS.

Postsplenectomy thromboembolic disease in congenital sideroblastic anaemia

This case report describes a case of congenital sideroblastic anaemia, one of the prototype disorders of erythroid haem biosynthesis. In this instance it was not recognised until after the patient had undergone splenectomy and developed refractory thromboembolic disease.

Dural venous thrombosis following splenectomy in a patient with hereditary spherocytosis

Hereditary spherocytosis is a common form of hemolytic anemia sometimes requiring splenectomy in recalcitrant cases. The complications of splenectomy include an increased risk of thrombosis, usually presenting with deep vein thrombosis or pulmonary embolism. However, common complaints such as headache should warn clinicians of involvement in less common sites, primarily the dural venous system. The case of dural venous thrombosis in a patient with hereditary spherocytosis and splenectomy is discussed. The potential mechanisms associated with thrombosis formation in this population and its treatment are discussed.

Delayed adverse vascular events after splenectomy in hereditary spherocytosis

BACKGROUND

It is probable that the variety and frequency of delayed adverse vascular events after splenectomy are underappreciated. Splenectomy is performed for a wide variety of conditions, and delayed postsplenectomy hazards are not often studied.

OBJECTIVE

To estimate the relative risk of adverse vascular events in members of hereditary spherocytosis families who have or have not had a splenectomy.

METHODS

Members of families in which hereditary spherocytosis exists were systematically questioned about adverse vascular events.

RESULTS

The cumulative incidence of arterial and venous events at age 70 years was greater in persons who had undergone a splenectomy for spherocytosis (arterial, 22% females, 32% males; venous, 20% females, 19% males) than in affected persons who did not undergo splenectomy (arterial, 3% females, 2% males; venous, 6% females, 4% males) or non-affected family members (arterial, 10% females, 17% males; venous, 4% females, 12% males). Affected subjects who undergo splenectomy are at greatly increased risk of arterial events as compared to affected subjects who do not undergo splenectomy [arterial, hazard ratio (HR) 7.2, 95% confidence interval (CI) 2.8-17.2; venous, HR 3.3, 95% CI 1.1-9.8].

CONCLUSION

There is a significant, long-lasting, increased risk of adverse arterial and venous thromboembolic events after splenectomy performed for hereditary spherocytosis. A review of the literature indicates that this is also true when splenectomy is performed for several other indications.

Laboratory markers of thrombosis risk in children with hereditary spherocytosis

BACKGROUND

Recent data suggest that adults with hereditary spherocytosis (HS) may be protected from atherothrombosis before splenectomy but have increased risk of thrombosis following splenectomy. In order to aid in making informed decisions regarding splenectomy in children with HS, we conducted a retrospective study of several surrogate laboratory markers of thrombosis risk in children with HS.

METHODS

A retrospective record review was performed on 246 children with HS. Platelet count and hemoglobin concentration were recorded prior to and following splenectomy in each patient. Serum cholesterol levels were collected from the record when available.

RESULTS

Prior to splenectomy, hypocholesterolemia was common. Mean platelet counts in 31 evaluable patients pre- and post-splenectomy were 334 and 608 x 10(9)/L, respectively (P < 0.001). Twenty-nine patients (94%) exhibited persistent thrombocytosis following splenectomy. Hemoglobin values following splenectomy often rose to higher than age and gender-matched norms, with 30% of measurements greater than the 90th percentile and 17% greater than the 97th percentile.

CONCLUSIONS

The findings of hypocholesterolemia before splenectomy and thrombocytosis and mild polycythemia afterwards support the hypothesis that patients with HS might be protected from thrombosis before splenectomy and/or more susceptible afterwards. Prospective studies of additional prothrombotic biomarkers and thrombotic events in HS patients are warranted.

Small bowel infarction in a patient with coeliac disease

A 40 year old man was admitted with a four week history of intractable diarrhoea and abdominal pain. A clinical diagnosis of inflammatory bowel disease was supported by biopsies of colonic mucosa. There was no response to Mesalazine and over 12 days the patient became critically ill with diarrhoea, hypovolaemia, and peritonism. A laparotomy was performed and 130 cm of infarcted ileum was resected. Extensive investigations excluded thrombophilia and echocardiography excluded intracardiac thrombus. Postoperatively the patient continued to have diarrhoea and he was diagnosed with coeliac disease on the basis of positive antiendomysial and antitissue transglutaminase autoantibodies and duodenal histology. Although there is no proof that mesenteric infarction occurred as a direct consequence of coeliac disease, clinicians should be aware of this possibility.

Coagulation and Splenectomy: An Overview

Venous thromboembolic events, such as pulmonary embolism, deep venous thrombosis, and portal vein thrombosis, have been observed in adult thalassemia patients, mainly in beta-thalassemia intermedia. The clinical findings are consistent with the observation of several alterations that indicate a state of activation of the hemostatic mechanisms in thalassemias. These alterations have usually been related to high platelet counts due to splenectomy and/or liver dysfunction. In a retrospective study of a large cohort of adults with thalassemia, we found a larger prevalence of venous thromboembolic events in transfusion-independent patients with thalassemia intermedia (29%) than in regularly transfused patients with thalassemia major (2%); moreover, the higher prevalence occurred particularly in splenectomized thalassemia intermedia patients. More recently, a multicenter study involving 56 tertiary referral centers in 7 countries was planned to assess the magnitude of thrombotic risk in thalassemia patients. The total number of patients who had thrombotic events was 146 (1.65%) out of 8860, with a prevalence of 0.9% in thalassemia major and 4% in thalassemia intermedia. The highest prevalence was confirmed in splenectomized patients. The observation that thrombotic events are more frequent in beta-thalassemia patients who are not receiving regular transfusions (thalassemia intermedia or thalassemia major patients in less developed countries with limited transfusion resources) or in thalassemic patients who have undergone splenectomy strongly supports the procoagulant activity of circulating damaged red blood cells.

Splenectomy and chronic thromboembolic pulmonary hypertension

BACKGROUND

An increased prevalence of splenectomy has been reported in patients with idiopathic pulmonary arterial hypertension. Examination of small pulmonary arteries from these subjects has revealed multiple thrombotic lesions, suggesting that thrombosis may contribute to this condition. Based on these findings, we hypothesised that splenectomy could be a risk factor for chronic thromboembolic pulmonary hypertension (CTEPH), a condition defined by the absence of thrombus resolution after acute pulmonary embolism that causes sustained obstruction of the pulmonary arteries and subsequent pulmonary hypertension.

METHODS

The medical history, clinical characteristics, thrombotic risk factors and haemodynamics of 257 patients referred for CTEPH between 1989 and 1999 were reviewed. In a case-control study the prevalence of splenectomy in patients with CTEPH was compared with that of patients evaluated during the same period for idiopathic pulmonary hypertension (n=276) or for lung transplantation in other chronic pulmonary conditions (n=180).

RESULTS

In patients with CTEPH, 8.6% (95% CI 5.2 to 12.0) had a history of splenectomy compared with 2.5% (95% CI 0.7 to 4.4) and 0.56% (95% CI 0 to 1.6) in cases of idiopathic pulmonary arterial hypertension and other chronic pulmonary conditions, respectively (p<0.01).

CONCLUSION

Splenectomy may be a risk factor for chronic thromboembolic pulmonary hypertension.

Thrombocytosis During Antifungal Therapy of Candidemia

BACKGROUND

Secondary, “reactive,” thrombocytosis has been attributed to bacterial infection and treatment with multiple pharmaceuticals and may be associated with an increase in the incidence of gastrointestinal tract bleeding and thrombotic events (eg, stroke).

OBJECTIVE

To characterize the dynamics of thrombocytosis in patients with candidemia receiving antifungal therapy.

METHODS

We initiated a retrospective observational description of patients with candidemia who were treated with antifungal agents. A total of 108 patients diagnosed with candidemia between August 1995 and September 2003 at our teaching hospital were enrolled. Three groups (candidemia with antifungal therapy, candidemia without antifungal therapy, antifungal therapy without candidemia) of patients >18 years of age were evaluated for the resence of thrombocytosis. Platelet administration, pharmacologic or pathologic contributors to thrombocytosis, and other pertinent details related to an elevation of platelet counts were scrutinized.

RESULTS

Reactive thrombocytosis was observed in approximately 10% of treated patients with candidemia. Within the subgroup developing reactive thrombocytosis, life-threatening thrombotic complications were uncommon. Mean baseline platelet counts were 393 × 103/mm3, with a mean peak (695 × 103/mm3) occurring an average of 13 days after initiation of therapy. All patients had resolution within 7 days after therapy. The maximum peak (1056 × 103/mm3) was observed in a patient after 14 days of antifungal therapy. The onset of thrombocytosis in this patient was 4 days and lasted 4 days after therapy.

CONCLUSIONS

Reactive thrombocytosis occurs during treatment of candidemia. The causative agent (drug vs disease), the risk associated with this reaction, and evaluation of treatment need to be elucidated by a larger epidemiologic study or controlled, prospective clinical trial.

Guidelines for the diagnosis and management of hereditary spherocytosis

Hereditary spherocytosis (HS) is a heterogeneous group of disorders with regard to clinical severity, protein defects and mode of inheritance. It is relatively common in Caucasian populations; most affected individuals have mild or only moderate haemolysis. There is usually a family history, and a typical clinical and laboratory picture so that the diagnosis is often easily made without additional laboratory tests. Atypical cases may require measurement of erythrocyte membrane proteins to clarify the nature of the membrane disorder and in the absence of a family history, occasionally molecular genetic analysis will help to determine whether inheritance is recessive or non-dominant. It is particularly important to rule out stomatocytosis where splenectomy is contraindicated because of the thrombotic risk. Mild HS can be managed without folate supplements and does not require splenectomy. Moderately and severely affected individuals are likely to benefit from splenectomy, which should be performed after the age of 6 years and with appropriate counselling about the infection risk. In all cases careful dialogue between doctor, patient and the family is essential. Laparoscopic surgery, when performed by experienced surgeons, can result in a shorter hospital stay and less pain.

The effects of vitamin E on platelet activity in β-thalassaemia patients

A double-blind, crossover, placebo-controlled study of the effect of vitamin E on platelet functions was performed on nine splenectomized and 16 non-splenectomized beta-thalassaemia/haemoglobin E (beta-thalassaemia/HbE) patients. The patients were supplemented with a daily dose of vitamin E (525 IU) for 3 months. The functions of platelets were assessed by adenosine diphosphate (ADP)-induced platelet aggregation and adenosine triphosphate release. Plasma alpha-tocopherol, plasma thiobarbituric reactive substances (TBARs) and serum ferritin levels represented patients' antioxidant status, lipid peroxidation status and iron status respectively. Before experimentation, all patients had low plasma alpha-tocopherol levels. The splenectomized patients showed severe iron overload iron, had higher plasma TBAR levels and their platelets were more reactive to ADP than those of non-splenectomized patients. Three months of daily vitamin E supplementation resulted in a significant increase in plasma alpha-tocopherol levels and reduction in plasma TBAR levels in all patients. Serum ferritin levels of the patients were not altered; however, vitamin E reduced the platelet reactivity of the splenectomized patients towards normal levels. The influence of vitamin E on platelet reactivity may result in delaying hypoxaemia and pulmonary occlusion that commonly occurs in splenectomized beta-thalassaemia/HbE patients.

Allogeneic bone marrow transplantation for severe post-splenectomy thrombophilic state in leaky red cell membrane haemolytic anaemia of the stomatocytosis class

The tendency for thrombosis to occur if haemolysis persists after splenectomy is especially marked in "hereditary stomatocytosis", in which the red cell membrane "leaks" Na and K. A 21-year-old woman, who was splenectomized in childhood for a congenital haemolytic state, presented with major pulmonary embolism that recurred despite anticoagulation. Tests showed a significant cation leak with a "shallow-slope" abnormality in temperature dependence. Allogeneic bone marrow transplantation caused the thrombophilic state to cease and subsequently anticoagulation was stopped without recurrence of thromboembolism. However, she died 9 months after transplantation: iron overload, intensified by the transfusion demands of the transplant, was a major factor.

Recurrent thromboembolic disease following splenectomy for pyruvate kinase deficiency

We report a case of recurrent thromboembolic disease and chronic pulmonary hypertension in an adult patient with pyruvate kinase deficiency who underwent splenectomy as a child. Thromboembolism has been reported as a complication following splenectomy for various hereditary chronic hemolytic anemias. To our knowledge, this association has not been described in patients specifically with pyruvate kinase deficiency. Our patient presented at age 37 with recurrent pulmonary emboli, 36 years after splenectomy for severe hemolytic anemia. Work-up for other hypercoagulable states was negative. The mechanism for hypercoagulability in this condition is unclear but may involve a quantitative or qualitative change in disrupted thrombogenic red blood cell membranes that would normally be removed by the spleen. Clinicians should have a high index of suspicion for thrombotic events in these patients, as early diagnosis and treatment can reduce morbidity and mortality, and chronic anticoagulation may help prevent the sequelae of repeated thromboembolic events.

The diagnosis and management of hereditary spherocytosis

Hereditary spherocytosis (HS) is relatively common in Caucasian populations; most individuals have mild or only moderate disease. There is commonly a family history and a typical clinical and laboratory picture so that the diagnosis is usually easily made without additional laboratory tests. Atypical cases may require measurement of membrane proteins and molecular genetics to clarify the nature of the membrane disorder. It is particularly important to rule out stomatocytosis because splenectomy is contraindicated because of the thrombotic risk. Mild HS can be managed without folate supplements and does not require splenectomy. Moderately and severely affected individuals are likely to benefit from splenectomy, which should be performed after the age of 6 and with appropriate counselling about the risk of infection. In all cases careful dialogue between physician, child and the family is essential. Laparoscopic surgery can result in shorter hospital stay and less pain.

The hereditary stomatocytoses and allied disorders: congenital disorders of erythrocyte membrane permeability to Na and K

The hereditary stomatocytoses and allied disorders are a set of dominantly inherited haemolytic anaemias in which the plasma membrane of the red cell 'leaks' sodium and potassium. There are about 10 different forms of these conditions, ranging from a moderately severe haemolytic anaemia to minor conditions in which the haematology is essentially normal, but where the patients present with pseudohyperkalaemia, due to leakage of K from the red cells on cooling to room temperature. Frequently misdiagnosed as atypical hereditary spherocytosis, these conditions can show marked thrombotic complications after splenectomy, which should be avoided. Laboratory studies of these conditions have drawn attention to a 32 kDa membrane protein, stomatin, which seems to act as a regulator of Na and K transport in human and animal tissues generally, but mutations in this gene do not cause these diseases. Genetic mapping in some kindreds, but not all, points to a mutation locus on chromosome 16.

Role of the spleen in the exaggerated polycythemic response to hypoxia in chronic mountain sickness in rats

In a rat model of chronic mountain sickness, the excessive polycythemic response to hypoxic exposure is associated with profound splenic erythropoiesis. We studied the uptake and distribution of radioactive iron and red blood cell (RBC) morphology in intact and splenectomized rats over a 30-day hypoxic exposure. Retention of (59)Fe in the plasma was correlated with (59)Fe uptake by both spleen and marrow and the appearance of (59)Fe-labeled RBCs in the blood. (59)Fe uptake in both the spleen and the marrow paralleled the production of nucleated RBCs. Splenic (59)Fe uptake was approximately 10% of the total marrow uptake under normoxic conditions but increased to 60% of the total marrow uptake during hypoxic exposure. Peak splenic (59)Fe uptake and splenomegaly occurred at the most intense phase of erythropoiesis and coincided with the rapid appearance of (59)Fe-labeled RBCs in the blood. The bone marrow remains the most important erythropoietic organ under both resting and stimulated states, but inordinate splenic erythropoiesis in this rat strain accounts in large measure for the excessive polycythemia during the development of chronic mountain sickness in chronic hypoxia.

Hereditary dehydrated and overhydrated stomatocytosis: recent advances

The hereditary stomatocytoses and allied disorders are genetic defects of the erythrocyte membrane that result in abnormal permeability to the univalent cations Na+ and K+. Although rare, these conditions reflect abnormalities in physiologic mechanisms that are of paramount interest. All cases (as defined here) show increased plasma membrane permeability to Na+ and K+ and, to a greater or lesser degree, stomatocytic morphology. Dehydrated hereditary stomatocytosis, the most common form of hereditary stomatocytosis, is more heterogeneous than previously thought and includes kindreds showing pseudohyperkalemia or perinatal edema, or both. The gene responsible for both dehydrated hereditary stomatocytosis and familial pseudohyperkalemia, a nonhemolytic variant that presents with high plasma K+ levels, has been mapped to 16q23-qter. The cause of overhydrated hereditary stomatocytosis remains elusive despite the manifest lack of the enigmatic protein stomatin in the erythrocyte membrane. In all cases where splenectomy has been performed, this procedure has conferred a marked risk for thrombosis in adult life. This finding stresses the importance of diagnostic distinction between these conditions and hereditary spherocytosis.

Aetiology and clinical significance of thrombocytosis: analysis of 732 patients with an elevated platelet count

OBJECTIVE

To determine the aetiology and clinical significance of an elevated platelet count (thrombocytosis) in a large cohort of patients.

DESIGN

A retrospective review of the medical records was performed on all patients, who had at least one platelet count > or = 500 x 10(9) L-1.

SETTING

Departments of Medicine and Surgery, University of Ulm, Germany.

SUBJECTS

A total of 732 patients with thrombocytosis.

MAIN OUTCOME MEASURES

Classification of thrombocytosis and thromboembolic complications, and evaluation of laboratory parameters distinguishing between primary and secondary thrombocytosis.

RESULTS

Of the total of 732 patients, 89 (12.3%) had primary and 643 (87.7%) had secondary thrombocytosis. Essential thrombocythaemia was observed in 40 of 89 patients (45%) with primary thrombocytosis. The most frequent causes of secondary thrombocytosis were tissue damage (42%), infection (24%), malignancy (13%) and chronic inflammation (10%). Primary thrombocytosis was significantly associated with a higher platelet count and an increased incidence of both arterial and venous thromboembolic complications. In secondary thrombocytosis, thromboembolic events were restricted to the venous system and occurred only in the presence of other risk factors. Mean values of leucocyte count, haematocrit, erythrocyte sedimentation rate, fibrinogen, serum potassium and lactate dehydrogenase were significantly different in primary and secondary thrombocytosis.

CONCLUSIONS

The finding of an elevated platelet count on routine blood examination has diagnostic, prognostic and therapeutic implications. It is of clinical importance to distinguish between primary and secondary thrombocytosis, as thrombotic complications occur more frequently in primary thrombocytosis. Unless additional risk factors are present, secondary thrombocytosis is not associated with a significant risk for thromboembolic events.

Severe thalassaemia intermedia: clinical problems in the absence of hypertransfusion

In many of the parts of the world where thalassaemia is common, the blood supply is inadequate or unsafe, and desferrioxamine is too expensive for routine use. We classify some patients as having 'severe thalassaemia intermedia', i.e. those with moderately severe thalassaemia who can survive without regular transfusions, but who are at risk of many complications which are reviewed here. These include bone deformity and fractures, extramedullary haemopoietic tumours, leg ulcers, autoimmune haemolysis and, especially after splenectomy, thromboembolism and infection. An increase in the quality and safety of the blood supply, and a cheaper and/or oral iron chelator, would enable more of these patients to be treated as thalassaemia major and have improved survival and quality of life.

Is there a correlation between raised erythropoietin and thrombotic events in sickle-cell anaemia?

Children with sickle-cell anaemia are predisposed to thrombotic strokes, the aetiology of which is unclear. We propose that erythropoietin, produced in response to chronic anaemia, is responsible for changes in platelet reactivity with a resulting increase in thromboses. This hypothesis is based on reports of enhanced aggregability of erythropoietin-driven platelets and an increased rate of thrombosis in patients receiving large doses of recombinant erythropoietin. Experiments in animals have shown that erythropoietin stimulates synthesis of platelets, that erythropoietin-driven platelets are hyper-reactive compared with age-matched control platelets, and that erythropoietin is pro-thrombotic. These data suggest that erythropoietin-dependent changes in platelet reactivity may potentiate thrombosis in sickle-cell anaemia, particularly in children who, compared with adults, have markedly higher erythropoietin concentrations and incidence of strokes.

Intravenous injection of sonicated blood induces pulmonary microthromboembolism in rabbits with ligation of the splenic artery

Pulmonary thromboembolism (PTE) is found in long hospitalized patients. Chronic PTE has been reported to play an important role in cardiac failure in thalassemic patients after splenectomy. However, the mechanism of PTE in these patients remains unclear. In this study, we attempted to establish an animal model of PTE. We divided New Zealand white rabbits into three groups: Group I was injected sonicated blood, II was injected non-sonicated blood after ligation of the splenic artery, and III was injected sonicated blood after ligation of the splenic artery. After injection of the sonicated blood, we examined the platelet counts every 10 minutes until 1 hour and the rabbits were sacrificed for histological examination. Platelets significantly decreased in number immediately after the injection of sonicated blood in Groups I and III. Many pulmonary thromboemboli composed mainly of platelets were found in Group III but not in other groups. These pathological changes seem to be partly similar to those of thalassemic patients after splenectomy. This animal model is thought to be useful to study the pathogenesis of pulmonary thromboembolism, especially in thalassemic patients after splenectomy.