Evaluation of the immature platelet fraction contribute to the differential diagnosis of hereditary, immune and other acquired thrombocytopenias.

The differential diagnosis of immune (ITP) and hereditary macrothrombocytopenia (HM) is key to patient management. The immature platelet fraction (IPF) represents the subset of circulating platelets with higher RNA content, and has been shown to distinguish hypo- from hyperproliferative thrombocytopenias. Here we evaluated the diagnostic accuracy of IPF in the differential diagnosis between HM and other thrombocytopenias in a population of patients with post-chemotherapy thrombocytopenia (n = 56), bone marrow failure (n = 22), ITP (n = 105) and HM (n = 27). TPO levels were also measured in HM and ITP matched for platelet counts. Platelet counts were similar in all patient groups. Higher IPF values were observed in both ITP (12.3%; 2.4-65.6%) and HM (29.8%; 4.6-65.9%) compared to hypoproliferative thrombocytopenias. IPF values were also higher in HM compared to ITP, yielding a diagnostic accuracy of 0.80 (95%CI 0.70-0.90; P < 0.0001) to distinguish these two conditions. Intra- and inter-assays reproducibility of IPF in HM patients revealed that this is a stable parameter. In conclusion, IPF is increased in HM compared to both ITP and other thrombocytopenias and contributes to the differentiation between ITP and HM. Further studies are warranted to understand the biological rationale of these findings and to its incorporation in diagnostic algorithms of HM.

Performance of a point-of-care device in determining prothrombin time in supra-therapeutic INRs.

INTRODUCTION: Point-of-care (POC) devices have been widely adopted for monitoring prothrombin time (PT) (INR) following the demonstration of their accuracy compared to standard INR determination. However, guidelines suggest confirmation of POC results when INRs increase above therapeutic range, due to concerns regarding possible inferior performance of POC devices in high INR levels. Unfortunately, patients with supra-therapeutic INRs are underrepresented in studies that validated these devices. METHODS: We performed a prospective evaluation of the performance of a POC device in monitoring oral anticoagulation in patients with INR values above 3.5 in a University outpatient anticoagulation clinic. During a 6-month period, 2322 INR determinations were performed with a POC device, and results above 3.5 were immediately repeated on an automated coagulometer. RESULTS: Dual INR determinations by two methods were obtained in 160 visits, with a mean INR from the POC device of 4.52 ± 0.96. Both classical statistics and clinical concordance analysis yielded satisfactory results when the two methods were compared. CONCLUSION: Our results demonstrate that POC devices present good correlation with standard laboratory methods for PT determination in supra-therapeutic INRs and that differences in clinical management do not support the need for systematic confirmation of these results in nonbleeding patients.