High serum transferrin receptor level in anemia of chronic disorders indicates coexistent iron deficiency

Blood transferrin receptor (TR) level is largely determined by the quantum of erythropoiesis and by intracellular iron content of the cells of the erythroid lineage. Hence, a high serum TR level has been found to be useful in distinguishing iron deficiency anemia (IDA) from anemia of chronic disorders (ACD). In order to examine its potential role in the diagnosis of concomitant iron deficiency in ACD, we determined serum TR levels in 130 cases of ACD, in 25 cases of IDA, and in 40 normal adults. As expected, all patients of IDA had significantly higher serum TR levels compared to the normal subjects (4.2-19.2 microg/dL vs. 1.3-3.0 microg/dL) (P < 0.002). In 11/25 cases of IDA, the total iron-binding capacity (TIBC) was in the normal range although bone marrow iron store was absent and serum TR levels were high, thereby highlighting the superiority of TR level in the diagnosis of iron deficiency compared to TIBC. Although 54% (70/130) patients of ACD had normal or low serum TR levels (0.9-3.0 microg/dL) as expected, in 46% (60/130) of ACD patients, serum TR levels were high (3.2-11.0 microg/dL). Mean corpuscular volume, red cell distribution width, and transferrin saturation were significantly lower (P < 0.001) in the latter group of patients compared to the former, and these parameters resembled those in IDA patients. Also, serum iron was lower and TIBC was higher in this group of ACD patients compared to those with normal or low serum TR. All these features point to an "IDA-like" profile of ACD patients with high TR and support the possibility of co-existent iron deficiency in this subgroup of ACD patients. In light of these observations it would be prudent to treat ACD patients with high serum TR levels with iron replacement therapy.     

Megakaryopoiesis and platelet function in polycythemia vera and essential thrombocythemia patients with JAK2 V617F mutation

Patients with Ph chromosome negative myeloproliferative disease (Ph-MPD) have an increased risk of vascular complications. It remains controversial whether patients with the JAK2 V617F mutation (V617F) exhibit increased risk, while recent growing evidence has shown a critical role for V617F in clonal erythropoiesis in Ph-MPD. We studied 53 patients with Ph-MPD especially in relation to megakaryopoiesis, the thrombotic complications and the presence of V617F. Using novel mutation-specific PCR which is a highly sensitive PCR-based assay for detection of JAK2 mutated allele(s), we identified V617F in 38 Ph-MPD, which include 13 polycythemia vera (PV), 23 essential thrombocythemia (ET) and 2 chronic idiopatic myelofibrosis. The numbers of megakaryocytes were significantly increased in PV and ET patients with V617F, but the platelet counts were slightly lower. Although statistically not significant, the incidence of thrombotic events was higher in the group with V617F compared to in those without the mutation. Agonist-induced in vitro platelet aggregation and platelet adhesion were not affected by the presence of this mutation. Nonetheless, we found a hypercoagulable state in Ph-CMPD with V617F by employing whole blood thromboelastography. It suggests pre-thrombotic tendencies in CMPD are complex and JAK2 V617F mutation might have a role in vivo blood coagulation by altering not only the number, but function(s) of all three myeloid cells, including red blood cells, white blood cells and platelets in Ph-CMPD.     

Front-line therapy in polycythemia vera and essential thrombocythemia

Because the current therapy in polycythemia vera (PV) and essential thrombocythemia (ET) is aimed at lowering the risk of thrombosis, the risk classification system in these disorders is shaped according to thrombotic risk. Patients with either PV or ET can be stratified in a "high-risk" or "low-risk" category according to their age and previous history of thrombosis. Whether novel risk factors such as leukocytosis and JAK2 mutation may be included in the prognostic stratification requires confirmation in prospective future clinical studies. The identification and appropriate management of cardiovascular risk factors and the promotion of a healthy lifestyle in chronic myeloproliferative neoplasms (MPN), as in the general population, should be considered a cornerstone of vascular prevention. Blood hyperviscosity in PV is a major cause of vascular disturbances which severely impact on morbidity and mortality. An aggressive target of hematocrit lower than 45% in males and 42% in females has been advised by the European LeukemiaNet (ELN) group, although no convincing evidence of this recommendation is currently available. The efficacy and safety of low-dose aspirin (100mg daily) in PV has been assessed in the European Collaboration on Low-dose Aspirin in Polycythemia (ECLAP) double-blind, placebo-controlled, randomized clinical trial. Translating evidence from the positive results of ECLAP to ET may be questionable. The most commonly used front-line therapy drugs for the treatment of high-risk PV and ET patients include hydroxyurea and alpha-interferon at any age while anagrelide is recommended as second line-therapy in resistant and intolerant ET patients. Busulphan is a front-line therapy in the elderly. By definition, children with ET are a population with low vascular risk unless a major thrombotic or hemorrhagic event has occurred. ELN recommends to prescribe cytoreductive drugs in children as a last resort. No results of clinical trials with JAK-2 inhibitor drugs in PV and ET are so far available.     

Differentiation between essential thrombocythemia and polycythemia vera with marked thrombocytosis

Accurate distinction between essential thrombocythemia and thrombocytotic polycythemia vera requires determination of the red cell mass in the presence of adequate iron stores, but this is not always possible. We therefore compared the clinical and laboratory features at the time of presentation of 50 patients with unequivocal essential thrombocythemia and 27 patients with thrombocytotic polycythemia vera. Univariate analysis failed to identify any single parameter capable of reliably separating the groups. A logistic regression algorithm incorporating hematocrit, white cell count, and spleen size markedly increased the diagnostic accuracy (92%) compared with predictions based on the hematocrit alone (52%). The algorithm's usefulness for patients with intermediate hematocrits was confirmed by analysis of independent samples of essential thrombocythemia and thrombocytotic polycythemia vera patients, and also by analysis of patients with probable essential thrombocythemia in whom the diagnosis could not be confirmed because of inadequate exclusion of polycythemia vera. Furthermore, comparison of survival data suggests that differentiating these disorders is prognostically important. The algorithm is recommended as an alternate method for differentiating essential thrombocythemia from thrombocytotic polycythemia vera whenever the red cell mass is unavailable or iron deficiency cannot be excluded.     

Platelet density in essential thrombocythemia and polycythemia vera

This study aims to compare platelet density in myeloproliferative disorders (essential thrombocythemia (ET) and polycythemia vera (PV)) with platelet density of healthy subjects. Platelet density peaks were determined using a specially designed apparatus for scanning light transmission variations along test tubes containing density-separated platelets. Eighteen patients with myeloproliferative disorders (nine ET and nine PV) were compared with a control group consisting of 12 healthy volunteers. Compared with healthy volunteers, patients with myeloproliferative disorders had significantly lower platelet peak density ( P< 0.001). It is concluded that determination of peak platelet density may be a useful tool for excluding ET and PV. A high platelet density peak makes a clonal disorder less likely and a low density peak would confirm the suspicion.     

Factor V Leiden mutation and the risk of venous thromboembolism in pregnant women.

BACKGROUND AND OBJECTIVES: In this retrospective, single center, cohort study we assessed the risk of pregnancy-related venous thromboembolism (VTE) in women belonging to a large number of families identified because of a symptomatic proband with single identified factor V Leiden mutation. DESIGN AND METHODS: Female family members who had experienced at least one full-term pregnancy were enrolled in the study. Two hundred and seventy pregnancies occurred in 105 carriers and 215 pregnancies in 81 non-carriers of factor V Leiden mutation. RESULTS: The frequency of VTE was 6.4% for heterozygous, 16.7% for homozygous, 20% for double heterozygous carriers of thrombophilic defects, and 1.2% for non-carriers. The majority of VTE events related to pregnancy occurred in the post-partum period. The relative risks of developing pregnancy-related VTE in women who were carriers of heterozygous and homozygous (or combined heterozygous) factor V Leiden mutation as compared to non-carriers were 5.3 (95% CI, 0.6 to 43.9) and 15.4 (95% CI, 1.4 to 164), respectively. INTERPRETATION AND CONCLUSIONS: Factor V Leiden mutation is a risk factor for pregnancy-related VTE, especially in its homozygous form and in combination with other thrombophilic abnormalities. Screening of families with this mutation might be useful for women of fertile age, as they may take advantage from thromboprophylaxis during pregnancy and the post-partum period.     

Aspirin responsive platelet thrombophilia in essential thrombocythemia and polycythemia vera

Essential thrombocythemia (ET) and polycythemia vera (PV) frequently present with erythromelalgia and acrocyanotic complications, migraine-like microvascular cerebral and ocular transient ischemic attacks (MIAs) and/or acute coronary disease. The spectrum of MIAs in ET range from poorly localized symptoms of transient unsteadiness, dysarthria and scintillating scotoma to focal symptoms of transient monocular blindness, transient mono- or hemiparesis or both. The attacks all have a sudden onset, occur sequentially rather than simultaneously, last for a few seconds to several minutes and are usually associated with a dull, pulsatile or migraine-like headache. Increased hematocrit and blood viscosity in PV patients aggravate the microvascular ischemic syndrome of thrombocythemia to major arterial and venous thrombotic complications. Phlebotomy to correct hematocrit to normal in PV significantly reduces major arterial and venous thrombotic complications, but fails to prevent the platelet-mediated erythromelalgia and MIAs. Complete long-term relief of the erythromelalgic microvascular disturbances, MIAs and major thrombosis in ET and PV patients can be obtained with low dose aspirin and platelet reduction to normal, but not with anticoagulation. Skin punch biopsies from the erythromelalgic area show fibromuscular intimal proliferation of arterioles complicated by occlusive platelet-rich thrombi leading to acrocyanotic ischemia. Symptomatic ET patients with erythromelalgic microvascular disturbances have shortened platelet survival, increased platelet activation markers β-thromboglobulin (β-TG), platelet factor 4 (PF4) and thrombomoduline (TM), increased urinary thromboxane B2 (TXB2) excretion, and no activation of the coagulation markers thrombin fragments F1+2 and fibrin degradation products. Inhibition of platelet cyclooxygenase (COX1) by aspirin is followed by the disappearance and no recurrence of microvascular disturbances, increase in platelet number, correction of the shortened platelet survival times to normal, and reduction of increased plasma levels of β-TG, PF4, TM and urinary TXB2 excretion to normal. These results indicate that platelet-mediated fibromuscular intimal proliferation and platelet-rich thrombi in the peripheral, cerebral and coronary end-arterial microvasculature are responsible for the erythromelalgic ischemic complications, MIAs and splanchnic vein thrombosis. Baseline platelet P-selectin levels and arachidonic acid induced COX1 mediated platelet activation showed a highly significant increase of platelet P-selectin expression (not seen in ADP and collagen stimulated platelets), which was significantly higher in JAK2^V617F mutated compared to JAK2 wild type ET.     

Iron deficiency: definition and diagnosis

There has been a continuous refinement over the past several decades of methods to detect iron deficiency and assess its magnitude. The optimal combination of measurements differs for clinical and epidemiological assessment. Clinically, the major problem is to distinguish true iron deficiency from other causes of iron-deficient erythropoiesis, such as the anaemia of chronic disease. Epidemiologically, techniques that provide quantified estimates of body iron are preferable. For both purposes, the serum ferritin is the focal point of the laboratory detection of iron deficiency. Serum ferritin measurements provide a reliable index of body iron stores in healthy individuals, a cost-effective method of screening for iron deficiency, and a useful alternative to bone marrow examinations in the evaluation of anaemic patients. Preliminary studies indicate that measurement of the serum transferrin receptor may be the most reliable way to assess deficits in tissue iron supply.     

Risk of thrombosis in patients with essential thrombocythemia and polycythemia vera according to JAK2 V617F mutation status

We compared the laboratory and clinical findings of 179 patients with essential thrombocythemia (ET) and 77 with polycythemia vera (PV) classified according to the presence of the JAK2 V617F mutation. A gradient was observed in laboratory values between patients with JAK2 wild-type ET, JAK2 V617F ET and PV (all of whom carried the JAK2 mutation). The rate of thrombotic complications in JAK2-positive ET patients was significantly higher than that in wild-type ET patients and not statistically different from that in PV patients.     

Progenitors homozygous for the V617F mutation occur in most patients with polycythemia vera, but not essential thrombocythemia

An acquired V617F JAK2 mutation occurs in patients with polycythemia vera (PV) or essential thrombocythemia (ET). In a proportion of V617F-positive patients, mitotic recombination produces mutation-homozygous cells that come to predominate with time. However, the prevalence of homozygosity is unclear, as previous reports studied mixed populations of wild-type, V617F-heterozygous, and V617F-homozygous mutant cells. We therefore analyzed 1766 individual hematopoietic colonies from 34 patients with PV or ET in whom granulocyte sequencing demonstrated that the mutant peak did not predominate. V617F-positive erythroid burst-forming units (BFU-Es) were more frequent in patients with PV compared with patients with ET (P = .022) and, strikingly, V617F-homozygous BFU-Es were detected in all 17 patients with PV, but in none of the patients with ET (P < .001). Moreover, mutation-homozygous cells were present in 2 patients with ET after polycythemic transformation. These results demonstrate that V617F-homozygous erythroid progenitors are present in most patients with PV but occur rarely in those with ET.     

Immunochemical Determination of Serum Transferrin: Reference Values,Correlation with Serum Total Iron-Binding Capacity and Value in the Diagnosis of Iron Deficiency Anaemia and Anaemia of Chronic Disorders

Immunologically determined reference values of serum transferrin are presented for adults and children. A good correlation between serum transferrin and total iron-binding capacity values was found. In 2 groups of anaemic patients - 51 patients with iron deficiency anaemia and 45 patients with anaemia of chronic disorders - serum transferrin determination distinguishes the two groups of anaemic patients from normals somewhat better than TIBC determination.     

JAK2V617F mutation and hydroxyurea treatment as determinants of immature platelet parameters in essential thrombocythemia and polycythemia vera patients

Immature platelets (IPFs), which are hemostatically more active than mature platelets, have been found elevated in essential thrombocythemia and polycythemia vera, 2 myeloproliferative neoplasms (MPN) characterized by an increased risk of thrombosis. It is not known whether the IPF levels are influenced by pathogenetic factors, including JAK2V617F mutational status, or by treatment regimen. To address this point, in 46 essential thrombocythemia and 38 polycythemia vera consecutive patients, we measured IPF and correlated the results to JAK2V617F mutation and myelosuppressive treatment with hydroxyurea. This analysis provides 2 new elements regarding IPF and MPN. The first finding is that the JAK2V617F mutation is linked to the quantity of IPF in patients with MPN, which might contribute to the prothrombotic phenotype in these patients. The second finding is that IPF is susceptible to myelosuppressive treatment, which may additionally explain the favorable effect of hydroxyurea therapy on MPN outcome as well as the associated thrombotic risk.     

Target hematologic values in the management of essential thrombocythemia and polycythemia vera

Treatment of essential thrombocythemia (ET) and polycythemia vera (PV) is aimed at preventing vascular complications, which are the main cause of morbidity and mortality in these diseases. Over the years, clinical trials have demonstrated that the incidence of thrombosis and bleeding can be reduced by controlling the blood cell counts, but the target hematological levels have varied across the studies. In this article, we review the evidence supporting the use of predefined target hematologic values for the management of ET and PV in routine clinical practice. At present, the recommended target hematocrit in PV is below 45%, regardless of the patients' risk profile. Concerning platelet counts, no direct correlation has been demonstrated with thrombotic risk in either ET or PV. Thus, although cytoreductive treatment reduces the rate of vascular complications in high‐risk patients, no particular threshold of the platelet counts has been shown to be more protective against thrombosis. Extreme thrombocytosis is a risk factor for bleeding, particularly when aspirin or anagrelide are given. Leukocytosis at baseline or during follow‐up appears to be a risk factor for thrombosis, mostly in high‐risk patients. However, the clinical benefit of strictly controlling this parameter is not yet established. Finally, standardized definitions of response to cytoreductive treatment in ET and PV have recently been published. Nevertheless, they have been produced to compare the efficacy of new therapies in clinical trials, whereas its relevance in clinical practice has been questioned in retrospective studies showing that such response definitions do not correlate with the patients' clinical outcome.     

The relationship between factor V Leiden, prothrombin G20210A, and MTHFR mutations and the first major thrombotic episode in polycythemia vera and essential thrombocythemia

Arterial and venous thrombosis are the most frequent complications in patients with polycythemia vera and essential thrombocythemia. We sought to demonstrate a possible contribution of the factor V Leiden, prothrombin G20210A, and methylenetetrahydrofolate reductase (MTHFR) 677 C?>?T and 1298 A?>?C mutations to the thrombotic risk in patients with polycythemia vera and essential thrombocythemia along with other biological features of these patients. We included 86 patients with polycythemia vera, of which 34 (39.5 %) had major thrombosis and 95 patients with essential thrombocythemia, of which 22 (23.1 %) had major thrombosis. In the whole cohort of patients, only the factor V Leiden mutation was significantly associated with both arterial and venous thrombosis in univariate and multivariate analysis (odds ratio (OR)?=?4.3; 95 % confidence interval (CI)?=?1.5–12.5; p?=?0.008 and OR?=?4.3; 95 % CI?=?1.2–15.9; p?=?0.02, respectively). Other factors significantly associated with thrombosis in both univariate and multivariate analysis were male sex (OR?=?2.8, 95 % CI?=?1.4–5.4, p?=?0.002 and OR?=?3.5, 95 % CI?=?1.6–7.6, p?=?0.002, respectively) and the JAK2 V617F mutation (OR?=?5.5, 95 % CI?=?2.1–15, p?=?0.0001 and OR?=?6.9, 95 % CI?=?2.2–21.2, p?=?0.001, respectively). In conclusion, among the four mutations analyzed (factor V Leiden, prothrombin G20210A, and MTHFR 677 C?>?T and 1298 A?>?C), only factor V Leiden is a major contributor to thrombosis in polycythemia vera and essential thrombocythemia.