Average Mean Platelet Volume Research Articles

Identification of Inherited Macrothrombocytopenias Based on Mean Platelet Volume among Patients Diagnosed with Idiopathic Thrombocytopenia.

Inherited macrothrombocytopenia is a rare illness that is often misdiagnosed as idiopathic thrombocytopenia (ITP), a more widespread acquired disease. The hallmark of a diagnosis of these diseases is the presence of giant platelets. Automated blood cell counters in routine clinical use usually miss giant platelets and underestimate mean platelet volume (MPV). Incorrect diagnoses might expose patients to a risk of unnecessary treatment. The ADVIA 120 hematology counter efficiently detects large platelets based on two-dimensional laser light scatter. This two-dimensional approach provides a more accurate estimation of platelet volume than conventional one-dimensional analysis. The present study measures and re-evaluates MPV using the ADVIA 120 in 112 patients who had initially been diagnosed with ITP.We identified 11 unrelated patients as having probable macrothrombocytopenia (average MPV of 19.2 ± 3.8 fL; normal range 7.8–10.2). A diagnosis of inherited macrothrombocytopenia was immediately ruled out in 5 of the 11 patients, because their medical records indicated that their platelet counts had once been normal or became normalized (>100x199/L) in response to steroid therapy. Of the remaining 6 patients, platelets aggregated abnormally in response to ristocetin in 3 patients and MYH9-RD was suspected in one patient since Döhle-like bodies were apparent in granulocytes on blood films. DNA analyses confirmed that 3 of these patients had Bernard-Soulier syndrome and 1 had MYH9-related disease, both of which are the most common forms of inherited macrothrombocytopenia. We detected 3 homozygous mutations in the 3 patients with Bernard-Soulier syndrome: A3171T and 4444insT in the GPIbα gene that created new premature termination codons, and the missense mutation, G1913A in the GPIX gene, that caused the loss of GPIX surface expression. In one patient with MYH9-related disease, we found a heterozygous missense mutation of C5797T in exon 40 of the MYH9 gene. We stress that all four patients had received high-dose steroid therapy and/or splenectomy before this study according to a diagnosis of ITP.Checking MPV using the ADVIA 120 in thrombocytopenic patients is a useful method of correctly diagnosing inherited macrothrombocytopenia, and thus avoiding patient exposure to unnecessary and sometimes toxic treatment.

Association of mean platelet volume with risk of stroke among 3134 individuals with history of cerebrovascular disease.

Mean platelet volume (MPV) is positively associated with measures of platelet activity and may be a useful indicator of the risk of vascular events in a variety of patient groups. The association of MPV with the risk of stroke was assessed in the Perindopril Protection Against Recurrent Stroke Study (PROGRESS). All participants had a history of cerebrovascular disease at baseline, and analyses were adjusted for the effects of potential confounders. The study followed 3134 individuals for an average of 3.9 years (mean age, 65 years; 71% male; average MPV, 10.0 fL). Three hundred eighty-three individuals had 402 stroke events, and 160 had major coronary events. MPV was positively associated with the risk of stroke, with an 11% increased relative risk (95% CI, 3% to 19%) of stroke per femtoliter greater MPV. There was no clear association of MPV with the risk of major coronary events (9% decreased relative risk; 95% CI, -23% to 7%). Perindopril did not alter MPV. MPV is an independent predictor of the risk of stroke among individuals with a history of stroke or transient ischemic attack. The measurement of MPV may add useful prognostic information for clinicians managing patients with a history of cerebrovascular disease.