The Prevalence and Biochemical Profiles of EDTA-Dependent Pseudothrombocytopenia in a Generally Healthy Population

Can Pseudothrombocytopenia be recognised at first look?

Our aim was to determine the laboratory parameters that distinguish pseudothrombocytopenia from true thrombocytopenia. A total of 107 patients who were referred to the adult hematology outpatient clinic with thrombocytopenia and subsequently diagnosed with acute myeloid leukaemia, immune thrombocytopenia and pseudothrombocytopenia were included in our study. Hemogram parameters on admission, platelet value in the control hemogram and peripheral smear findings were recorded. Forty three (40.2%) males and 64 (59.8%) females, were included in our study. There were 25 patients in the leukaemia group, 39 in the immune thrombocytopenia group and 43 in the pseudothrombocytopenia group. Control platelet value and red cell distribution width/platelet ratio were found to be statistically significantly different between the 3 groups. Receiver operating characteristic analysis based on platelet values showed that platelet value ≤ 38,000/µL (86% sensitivity, 78.1% specificity, P < .001), difference between 2 consecutively measured platelet levels ≤ 11. 000/µL (79.1% sensitivity, 79.7% specificity, P < .001), red cell distribution width/platelet ratio ≥ 0.413 (90.7% sensitivity, 78.1% specificity, P < .001) were found to be in favor of true thrombocytopenia. In the differentiation of pseudothrombocytopenia and true thrombocytopenia, the difference between the hemogram parameters at the time of admission and the platelet count in the control blood count may be guiding. This result may reduce patient and physician anxiety and prevent patient referral.

Pseudothrombocytopenia, beyond a laboratory phenomenon: study of 192 cases

The platelet antibodies that cause pseudothrombocytopenia (PTCP) act only in vitro and do not produce clinical bleeding. Most studies on PTCP have focused on improving differential diagnosis with true thrombocytopenia but studies on the characteristics of patients with PTCP are limited. In this study, we aimed to evaluate the clinical and biological characteristics of 192 patients with PTCP. In addition to general variables, we evaluated automated and microscopic platelet counts, platelet clumps, platelet diameters, immature platelet fraction (IPF), and platelet antibodies. Adult women accounted for the largest subgroup of patients (n=82; 42.7%) and 67 patients (34.9%) were grouped into families. Forty-four patients (22.9%) had one or more associated autoimmune disorders (ADs); 39 relatives of these patients (19.8%) had ADs and 45 relatives (23.4%) had immune thrombocytopenia (ITP) or unspecified thrombocytopenia. Platelet cryptantibodies and/or autoantibodies were positive in 56 patients (30.1%). Most patients (n=169; 80%) had automated platelet counts >80×10⁹/L. In all patients, microscopic platelet counts were ≥150×10⁹/L. The platelet clump index (% increase in microscopic platelet count compared to automatic count) ranged from 30 to >7000%. Platelet diameters and IPF parameters were significantly greater in the PTCP versus healthy controls (p<0.001). A total of 17 patients (8.8%) had had previous ITP or the PTCP evolved into ITP. Our data suggest that PTCP should be considered a situation of autoimmunity; the assessment of platelet clumps has a high diagnostic value; the close association between ITP and PTCP suggests that these conditions could be different phases of the same process.

Comparison of platelet count results on the Sysmex XN between citrate or MgSO4 and K2 EDTA anticoagulants

INTRODUCTION

The aim of this study performed on Sysmex XN is to compare platelet values on citrate and MgSO₄ (TBX) in patients with K2EDTA-induced platelet clusters and to identify platelet biases of these matrices compared to K2EDTA.

METHODS

Sixty patients with K2EDTA-induced platelet clusters were re-sampled with K2EDTA, citrate and TBX. Platelet results were then compared, and smears were analysed for clumping. Platelet results from 120 patients without K2EDTA-induced platelet clusters were compared between K2 EDTA, citrate, and MgSO₄ with impedance and fluorescence modes. Biases from regressions were analysed.

RESULTS

Out of the 60 patients with K2EDTA-induced platelet clusters, none showed platelet clusters with MgSO₄ whereas 50% still showed clusters with citrate. Among those without platelet clusters on citrate, the mean relative difference between (citrate- MgSO₄ )/MgSO₄ was -12.7% in impedance and -9.8% in fluorescence. Among the 120 patients without K2EDTA-induced platelet clusters, in fluorescence the mean relative bias with respect to K2EDTA was -2.06% for MgSO₄ and -10.3% for Citrate. For the MgSO₄ versus K2 EDTA regressions, the maximum absolute values of the 95% CI of the relative biases at 150 × 10⁹ /L (5.45%) and 450 × 10⁹ /L (3.56%) were below the desirable analytical objectives of the EFLM.

CONCLUSION

In patients with K2EDTA-induced platelet clusters, MgSO₄ is preferable to citrate. MgSO₄ provides a bias with XN in fluorescence when compared to EDTA which is within analytical tolerance.

Pseudothrombocytopenia-A Review on Causes, Occurrence and Clinical Implications

Pseudothrombocytopenia (PTCP), a relative common finding in clinical laboratories, can lead to diagnostic errors, overtreatment, and further (even invasive) unnecessary testing. Clinical consequences with potential life-threatening events (e.g., unnecessary platelet transfusion, inappropriate treatment including splenectomy or corticosteroids) are still observed when PTCP is not readily detected. The phenomenon is even more complex when occurring with different anticoagulants. In this review we present a case of multi-anticoagulant PTCP, where we studied different parameters including temperature, amikacin supplementation, measurement methods, and type of anticoagulant. Prevalence, clinical risk factors, pre-analytical and analytical factors, along with clinical implications, will be discussed. The detection of an anticoagulant-dependent PTCP does not necessarily imply the presence of specific disorders. Conversely, the incidence of PTCP seems higher in patients receiving low molecular weight heparin, during hospitalization, or in men aged 50 years or older. New analytical technologies, such as fluorescence or optical platelet counting, will be soon overturning traditional algorithms and represent valuable diagnostic aids. A practical laboratory approach, based on current knowledge of PTCP, is finally proposed for overcoming spuriously low platelet counts.

Hematologic reference intervals of Danish sows at mid-gestation

Hematologic reference intervals are useful tools for interpretation of laboratory results in swine practice and research. Until now, there were no hematologic reference intervals established for gestating Danish sows and those established in other countries are either out-dated, produced using very few sows or incomplete with few variables. In the past few decades there have been significant increases in litter size due to breeding, as well as the development of new analytical procedures for hematology and statistical procedures for calculating reference intervals. Therefore, hematologic reference intervals representing current pig production and technology are greatly needed. The main objective of this study was to provide updated and complete hematologic reference intervals for Danish sows at mid-gestation. Blood samples were collected at mid-gestation from 248 sows belonging to five commercial herds in Denmark and the samples were analysed for several hematologic variables using the Advia 2120i Hematology System. The reference intervals were calculated according to the guidelines of American Society for Veterinary Clinical Pathology. The reference interval for hemoglobin concentration was 103.1-145.0 g/L. For red blood cells, hematocrit and mean corpuscular volume, the 95% reference intervals were 4.98-7.50 × 10¹²/L, 0.32-0.47 L/L, 57.0-69.3 fL, respectively. The reference intervals established in this study are different from those previously reported in the literature. These reference intervals add to the current knowledge and will be useful in the prevention, diagnosis and treatment of several disease conditions in gestating sow populations.