Ethylenediaminetetraacetic acid-dependent pseudothrombocytopenia associated with neuroendocrine carcinoma: A case report

Transient EDTA-dependent pseudothrombocytopenia and ulcerative colitis recurrence during chemotherapy: A case of misleading platelet count results attributable to a laboratory artifact

Key Clinical Message

EDTA-dependent pseudothrombocytopenia as well as myelosuppression should be suspected when thrombocytopenia occurs in patients with autoimmune disease during chemotherapy.

Abstract

A patient with pancreatic cancer and ulcerative colitis developed transient ethylenediaminetetraacetic acid (EDTA)-dependent pseudothrombocytopenia with exacerbation of ulcerative colitis during chemotherapy. Unfortunately, pseudothrombocytopenia could not be immediately detected because thrombocytopenia was masked by a reasonable time course of adverse events associated with chemotherapy and ulcerative colitis recurrence. When thrombocytopenia occurs during chemotherapy, especially in patients with autoimmune diseases, EDTA-dependent pseudothrombocytopenia and bone marrow suppression caused by anti-cancer agents should be suspected.

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.

Surgical Delay due to Ethylenediaminetetraacetic Acid-Induced Pseudothrombocytopenia

Automated hematology analyzer uses the Coulter principle leading to different cell types based on their size. Despite being rapid and convenient, it can result in spurious outcomes like ethylenediaminetetraacetic acid (EDTA)-induced pseudothrombocytopenia. EDTA-induced pseudothrombocytopenia is an immunologically mediated phenomenon resulting from a change in the configuration of glycoprotein (GP) IIb/IIIa by EDTA. The consequence is an exposure of hidden epitope that reacts with certain autoantibodies resulting in spuriously low platelet counts when the blood samples are evaluated by automated blood analyzers. Although it is a rare cause of thrombocytopenia, if not recognized, it can result in unnecessary investigations and treatments. In this case, EDTA-induced psuedothrombocytopenia delayed laparoscopic cholecystectomy planned for symptomatic cholelithiasis in a 58-year-old male. The presence of large platelet clumps on peripheral smear and normal manual platelet counts confirmed the diagnosis. Pseudothrombocytopenia should be suspected when there is no correlation between clinical and laboratory findings in a patient with a low platelet count. Reperforming counts with other anticoagulants and if necessary, manual count in the peripheral blood smear is suggested.

Pseudothrombocytopenia: a case of platelet satellitism and phagocytosis by neutrophils

Thrombocytopenia is a clinically important condition that can lead to several problems when not correctly diagnosed. A decrease of platelet counts due to an in vitro phenomenon, Pseudothrombocytopenia, can be misunderstood and unnecessarily treated. The present case study describes a 57-year-old male with a history of pancreas adenocarcinoma and a current Staphylococcus aureus infection without any signs or symptoms that could explain the low levels of platelets obtained after blood analysis. Blood smear evaluation detected both platelet satellitism and phagocytosis by neutrophils. As this sample was anticoagulated with ethylenediaminetetraacetic acid (EDTA), a new blood sample with citrate was analyzed. Platelet count was normal and no morphological abnormalities were detected. This case emphasizes the need for considering not only laboratory results but also the patient clinical information to guarantee the correct diagnosis and the best treatment possible.

An Episode of Pseudothrombocytopenia during Pembrolizumab Therapy in NSCLC Patient

Immunotherapy with immune checkpoint inhibitors (ICI) is a new option of treatment in a growing range of neoplasms. In addition to an antitumor effect, ICI are associated with autoimmune reactions resulting in a wide spectrum of toxicities that have not been seen in patients receiving chemotherapy. In this article, we present a case of a patient with advanced lung adenocarcinoma who developed an EDTA-dependent pseudothrombocytopenia (PTCP) during pembrolizumab therapy. To the best of our knowledge, this is the first reported case of EDTA-dependent PTCP occurring during immunotherapy treatment of nonsmall lung cell cancer with ICI. The phenomenon of EDTA-dependent PTCP may prompt clinical decisions, as unnecessary transfusions or even exclusion from pembrolizumab therapy. Therefore, it is important to be aware of PTCP as a possible side effect of this therapy.

Correction of spurious low platelet counts by optical fluorescence platelet counting of BC-6800 hematology analyzer in EDTA-dependent pseudo thrombocytopenia patients

Background

To evaluate the dissociation effect of optical fluorescence platelet counting of BC-6800 hematology analyzer on ethylene diamine tetraacetic acid-dependent pseudo thrombocytopenia (EDTA-PTCP) samples.

Methods

Twenty-three finally identified EDTA-PTCP samples were recruited in this study using criteria as follow: (I) impedance platelet counts lower than 100×10⁹/L with instrument “platelet aggregation” flag; (II) existence of platelet clumps in the blood smear; (III) obviously higher platelet counts without “platelet aggregation” flag and no platelet clumps in blood smear after repeating phlebotomy using citrate anticoagulated tubes. The BC-6800 hematology analyzer and the XE-2100 hematology analyzer were used to test 23 EDTA-PTCP samples and 30 controls on both the impedance channel and the reticulocyte channel. The dissociation rate was defined as optical fluorescence platelet counts in the EDTA tubes/impedance platelet counts in citrate tubes ×100%.

Results

BC-6800 analyzer’s optical fluorescence platelet counts of EDTA-PTCP samples were significantly higher than impedance platelet counts (t=4.33, P=0.00) and comparable with the platelet counts of re-collected samples in tubes containing citrate anticoagulant. On BC-6800 hematology analyzer, 22 of 23 EDTA-PTCP samples showed a dissociation rate greater than 80%, and the average dissociation rate was 93%. On the XE-2100 hematology analyzer, 1 of the 17 EDTA-PTCP samples showed a dissociation rate greater than 80%, and the average dissociation rate was 56%.

Conclusions

Optical fluorescence platelet counting of BC-6800 Hematology Analyzer is effective for the correction of spurious low platelet counts in EDTA-PTCP patients, and its dissociation effect on EDTA-PTCP samples was independent of fluorescent dye staining.

Poorer prognosis with ethylenediaminetetraacetic acid-dependent pseudothrombocytopenia: a single-center case-control study

In ethylenediaminetetraacetic acid (EDTA)-dependent pseudothrombocytopenia (PTCP), automated platelet counts are lower than actual counts because of EDTA-induced aggregation. Factors contributing to the incidence of EDTA-PTCP are unknown, and no study has assessed the prognosis of EDTA-PTCP patients. This retrospective study assessed characteristics in EDTA-PTCP patients and matched controls to determine differences in prognosis. A retrospective case-control study was designed. From the University of Tokyo Hospital database, we identified patients diagnosed with EDTA-PTCP between 2009 and 2012, and performed 1:2 case:control matching for age and sex. A control group of sex- and age-matched patients was selected at random from the same database. We investigated differences in the frequency of complications, medication history, and blood transfusion history between the groups at the time of blood collection. Prognosis was evaluated using multivariate Cox regression analysis adjusting for age, sex, autoimmune disease, liver disease, and malignant tumor. We identified 104 EDTA-PTCP patients and 208 matched controls. The median age was 69.0 years (interquartile range: 54-76), with men comprising 51%. EDTA-PTCP patients had a higher frequency of malignant tumor and a lower frequency of hypertension and diabetes than controls. After adjustment for background factors, prognosis of EDTA-PTCP patients was significantly poorer than controls (hazard ratio, 11.8; 95% confidence intervals, 2.62-53.54). In conclusion, EDTA-PTCP patients had higher mortality, and EDTA-PTCP may need to be recognized as an indicator of worse prognosis.

EDTA-induced pseudothrombocytopenia in association with bladder cancer

Pseudothrombocytopenia is the detection of low platelet counts by an autoanalyser despite lack of shortage in platelets. EDTA-induced pseudothrombocytopenia, the most frequently seen form in clinical practice, occurs mainly due to reaction of antiplatelet antibodies. Pseudothrombocytopenia is not only seen in healthy individuals but it is also reported in association with autoimmune, cardiovascular and liver parenchyma diseases and malignancy. We aimed to review approaches to pseudothrombocytopenia by presenting a case in which EDTA-dependent thrombocytopenia in association with bladder tumour was detected during examination for haematuria.

Chronic subdural hematoma in elderly patient with EDTA-dependent pseudothrombocytopenia recently treated with aspirin and warfarin: case report

A 78-year-old man who had a history of myocardial and cerebral infarction and who was treated with aspirin and warfarin, presented with left chronic subdural hematoma. Cerebral computed tomography showed severe brain compression of hematoma with midline shift, indicating the need for emergent surgery. The hematology and clotting tests upon admission revealed severe thrombocytopenia (platelet count, 1.3 × 10⁴/μL) with normal clotting activity. Because platelet aggregation was evident in the smear, we re-examined the patient for hematology using tubes that contained heparin, showing also low platelet count (2.3 × 10⁴/μL). The day on admission, we performed irrigation and drainage of the chronic subdural hematoma through single burr-hole craniostomy. During surgery, we used 10 units of platelet concentrates (PCs) for the reason that the patient was taking aspirin and coagulopathy derived from low platelet count could not be excluded. After surgery, we re-evaluated the hematology of the blood stored in tubes that contained ethylenediaminetetraacetic acid (EDTA) with or without kanamycin (KM). Treatment with KM dissociated EDTA-induced platelet aggregation and revealed platelet counts with highest accuracy (no KM treatment, 1.3 × 10⁴/μL; KM treatment, 15.2 × 10⁴/μL). This phenomenon is called EDTA-Dependent Pseudothrombocytopenia (PTCP) defined as falsely low platelet counts reported by automated hematology analyzers due to platelet aggretgation. Awareness of the phenomenon will enable neurosurgeons to manage patients with PTCP appropriately and clinical laboratory especially in emergency hospital is recommended to prepare for the hematological tubes being added KM in routine analysis, resulting in preventing mistaken diagnosis.