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Spurious thrombocytopenia is a well-known phenomenon observed with the widespread use of hematology analyzers (HAs). In this study, 355 specimens with pseudo-thrombocytopenia (PTCP) were evaluated via epidemiology, identification, remedies, and platelet (PLT) count. Data showed that anticoagulants such as citrate and/or heparin-dependent PTCP (16.0%) became increasingly common, whereas ethylenediaminetetraacetic acid (EDTA)-induced PTCP (49.1%) remained the most frequent. We note that that nearly half of the patients with PTCP had veritable decreased PLT counts, even after PLT levels had been corrected. Our findings suggest that there were seasonal changes in patients with PTCP: PLT levels were higher in spring, compared with other seasons, with winter levels being the lowest. There were higher risks of PTCP for individuals with malignant neoplasms, liver diseases, infection, and hematologic disease, compared with other conditions. PTCP is related to diseases, rather than being a simple phenomenon, and thus demands careful attention.

Acute profound thrombocytopenia may be associated with the administration of eptifibatide, a glycoprotein antagonist. A case report of a 61-year-old male is presented. The reported incidence of acute profound thrombocytopenia associated with eptifibatide is 0.1% to 1.0% and usually occurs within 24 hours following therapy. However, cases of profound thrombocytopenia have been reported to occur within 1 to 4 hours following infusion. Platelet counts should be monitored in patients receiving eptifibatide at least within 24 hours and preferably within 2 to 4 hours after administration. Submitted 5.8.06 | Revisions Received 6.28.06 | Accepted 7.17.06

A comparison study between the standard glass hemacytometer and a disposable plastic cell counting slide was conducted. One hundred eleven body fluids and 77 whole-blood specimens were counted in parallel by the two manual methods. Excellent correlation was found in red blood cell counts (slope=1.00, r=0.99, n=94), white blood cell counts (slope=0.89, r=0.99, n=96), and platelet counts (slope=0.99, r=0.93, n=68) over a wide range of clinically significant values. The disposable plastic hemacytometer was found to be a useful alternative to the standard glass hemacytometer and offered the additional advantage of reducing technologist exposure to potentially infectious patient specimens.

Clumping of platelets in blood anticoagulated with EDTA is a main cause of reports of falsely low platelet counts by automated analyzers. To obtain reliable platelet counts in such cases, laboratorians often collect and analyze a citrated or nonanticoagulated blood specimen. The patient thus is subjected to a second venous or capillary puncture, and the availability of results is delayed. Our data on an alternative approach suggest that reliable automated platelet counts can be obtained from many blood specimens that reveal microscopic platelet clumps after mixing them by vortex and rerunning the samples through the analyzer. Mixing the blood by vortex at the maximum possible speed for 1 to 2 minutes disaggregated platelet clumps completely in 44% of specimens and partially in another 49% of specimens.

Precision of platelet enumeration by phase microscopy, electrical impedance (Coulter's ZBI and Thrombocounter), and laser forward light scattering (Ortho El.T-8) technologies were evaluated. Samples from 30 patients were separated into high-, medium-, and low-range platelet counts, and each sample was counted by the three techniques. Results with the ELT-8 were more precise and reproducible, especially when measuring low platelet counts. Similar results were obtained by phase microscopy and the ZBI. The Thrombocounter produced a wide fluctuation of counts.

We developed a computerized algorithm for real-time hematology delta checks, comparisons between current and previous patient automated blood cell counts. Delta checking is restricted to an arbitrarily set maximum of seven days and uses linear as well as variable-rate nonlinear discriminant functions.Two delta levels were used–one for intralaboratory use and one requiring interaction with the referring unit or physician. The delta checks are useful for (1) random error detection mainly using a combination of two RBC parameters, mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH), that remain stable over time; (2) warning for significant clinical changes in hemoglobin, MCV, WBC, and/or platelets; and (3) the elimination of manual checks on abnormal RBC morphology, WBC counts, and for platelet counts in specimens with repeatedly abnormal values.

Quality control of the platelet count can be assured by estimating the platelet count from the peripheral blood smear. The Miller’s Disc, designed for counting reticulocytes, can be used to enumerate platelets on a stained peripheral blood smear. The resultant platelet count is multiplied by the red cell count to obtain an accurate platelet estimation.