The use of mean platelet volume for distinguishing the causes of thrombocytopenia in adult patients

A Systematic Review and Meta-Analysis of Mean Platelet Volume and Platelet Distribution Width in Patients with Obstructive Sleep Apnoea Syndrome

Obstructive sleep apnoea syndrome (OSAS) is a highly prevalent yet underestimated disorder caused by the complete or partial obstruction of the upper airways. Although polysomnography is the gold standard for OSAS diagnosis, there is an active search for easily accessible biomarkers of disease presence and severity, particularly those reflecting morphological changes in specific blood cells. We investigated the associations between the presence and severity of OSAS, continuous positive airway pressure (CPAP) treatment, mean platelet volume (MPV), and platelet distribution width (PDW), routinely assessed as part of the complete blood count. From 262 retrieved records from PubMed, the Web of Science, Scopus, and Google Scholar, 31 manuscripts were selected for a final analysis, 30 investigating MPV and 15 investigating PDW. MPV was not statistically different between OSAS patients and healthy controls; however, it progressively increased with disease severity. By contrast, OSAS patients had significantly higher PDW values than controls (SMD = 0.40, 95% CI: 0.25 to 0.56; p ˂ 0.001), and the difference increased with disease severity. In a univariate meta-regression, there were significant associations between the MPV and publication year, the apnoea-hypopnea index, and diabetes mellitus, while no associations were observed with the PDW. No significant between-group differences were observed in the subgroup analyses. These data suggest that PDW, and to a lesser extent, MPV, are potential biomarkers of OSAS and require further research to ascertain their pathophysiological significance (PROSPERO, CRD42023459413).

The diagnostic accuracy of mean platelet volume in differentiating immune thrombocytopenic purpura from hypo-productive thrombocytopenia: A systematic review and meta-analysis

BACKGROUND

Thrombocytopenia is defined as a decreased number of platelets in the circulating blood as a result of hypo-proliferation in marrow or peripheral destruction of platelets. Several diagnostic methods have been proposed to discriminate the underline cause of thrombocytopenia. Recent studies showed that mean platelet volume (MPV) could be used for differential diagnosis of immune thrombocytopenic purpura (ITP). Thus, we aimed to investigate the diagnostic accuracy of MPV for differential diagnosis of ITP from hypo-productive thrombocytopenia.

METHODS

This study was conducted in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines (PRISMA). The study protocol was registered on PROSPERO with the reference number CRD42023447789. Relevant published studies that were published up to April 10, 2023, in peer-reviewed journals were searched on electronic different databases. The methodological quality of the included studies was appraised using the quality assessment of diagnostic accuracy studies 2 (QADAS-2) tool. The pooled weight mean difference (WMD) of MPV between the ITP group and hypo-productive group was analyzed using a random-effects model meta-analysis. Relevant data were extracted using a Microsoft Excel spreadsheet and analyzed using STATA 11.0 and Meta-disc 1.4 software. Publication bias was evaluated using Deek's funnel plot asymmetry test.

RESULTS

A total of 14 articles were included in this systematic review and meta-analysis. The comparison of MPV between groups revealed that the pooled mean value of MPV increased significantly in ITP patients compared to patients with hypo-productive thrombocytopenia (WMD = 2.03; 95% CI, 1.38-2.69). The pooled sensitivity and specificity of MPV in differentiating ITP from hypo-productive thrombocytopenia were 76.0% (95% CI: 71.0%, 80.0%) and 79.0% (95% CI: 75.0%, 83.0%), respectively. The summary positive likelihood ratio (PLR) and negative likelihood ratio (NLR)using the random effects model were 3.89 (95% CI: 2.49, 6.10) and 0.29 (95% CI: 0.18, 0.46), respectively.

CONCLUSION

MPV can be used to discriminate ITP from hypo-productive thrombocytopenia. It can possess large advantages as it is noninvasive, simple, quick, inexpensive, easy to perform, reliable, and routinely generated by automated cell counters.

Serotonin reduction in post-acute sequelae of viral infection

Post-acute sequelae of COVID-19 (PASC, "Long COVID") pose a significant global health challenge. The pathophysiology is unknown, and no effective treatments have been found to date. Several hypotheses have been formulated to explain the etiology of PASC, including viral persistence, chronic inflammation, hypercoagulability, and autonomic dysfunction. Here, we propose a mechanism that links all four hypotheses in a single pathway and provides actionable insights for therapeutic interventions. We find that PASC are associated with serotonin reduction. Viral infection and type I interferon-driven inflammation reduce serotonin through three mechanisms: diminished intestinal absorption of the serotonin precursor tryptophan; platelet hyperactivation and thrombocytopenia, which impacts serotonin storage; and enhanced MAO-mediated serotonin turnover. Peripheral serotonin reduction, in turn, impedes the activity of the vagus nerve and thereby impairs hippocampal responses and memory. These findings provide a possible explanation for neurocognitive symptoms associated with viral persistence in Long COVID, which may extend to other post-viral syndromes.

Secondary Immune Thrombocytopenia Due to Mycoplasma pneumoniae Without Clinically Significant Evidence of Active Infection

Immune thrombocytopenia (ITP) is a leading cause of isolated thrombocytopenia characterized by autoantibody-mediated destruction of platelets, impaired megakaryocyte function, and pathologic T-cell recognition of platelet antigens. Several triggers for ITP have been identified. Treatment of the inciting cause decreases the antibodies responsible for molecular mimicry, and these cases are usually associated with a better outcome with a decreased probability of progression to chronic ITP. Mycoplasma pneumoniae infection is known to have extrapulmonary manifestations, and growing evidence suggests it can be a cause of secondary ITP. Many of the described cases report evidence of a pulmonary infection with severe mucosal bleeding. Here, we describe an interesting case of a patient presenting with isolated thrombocytopenia with mild mucosal bleeding, later found to be positive for Mycoplasma immunoglobulin M without clinically significant evidence of active infection. Currently, mycoplasma testing is not routinely performed as a workup for ITP. However, clinicians may consider this before proceeding with more aggressive treatment for refractory ITP (i.e., prolonged immunosuppression, splenectomy). This case illustrates that mild/asymptomatic Mycoplasma infection can also be associated with ITP.

Bardet-Biedl Syndrome ciliopathy is linked to altered hematopoiesis and dysregulated self-tolerance

Bardet-Biedl Syndrome (BBS) is a pleiotropic genetic disease caused by the dysfunction of primary cilia. The immune system of patients with ciliopathies has not been investigated. However, there are multiple indications that the impairment of the processes typically associated with cilia may have influence on the hematopoietic compartment and immunity. In this study, we analyze clinical data of BBS patients and corresponding mouse models carrying mutations in Bbs4 or Bbs18. We find that BBS patients have a higher prevalence of certain autoimmune diseases. Both BBS patients and animal models have altered red blood cell and platelet compartments, as well as elevated white blood cell levels. Some of the hematopoietic system alterations are associated with BBS-induced obesity. Moreover, we observe that the development and homeostasis of B cells in mice is regulated by the transport complex BBSome, whose dysfunction is a common cause of BBS. The BBSome limits canonical WNT signaling and increases CXCL12 levels in bone marrow stromal cells. Taken together, our study reveals a connection between a ciliopathy and dysregulated immune and hematopoietic systems.

Diagnostic importance of mean platelet volume, platelet distribution width and platelet large cell ratio as screening tool in immune thrombocytopenia

Objective

To determine diagnostic importance of mean platelet volume (MPV), platelet distribution width (PDW) and platelet large cell ratio (PLCR) in diagnosing cases of immune thrombocytopenia.

Methodology

The study was done in Khyber Teaching hospital from January 2017 to May 2018. Cases with low platelet count of all the ages and both the genders were included in the study by non probability purposive sampling technique and were subjected to bone marrow aspiration to rule out other causes of thrombocytopenia and thus confirm the diagnosis of immune thrombocytopenia. The platelet indices were noted and their sensitivity, specificity and accuracy were determined for immune thrombocytopenia. Mean and standard deviation were used for quantitative data. Percentage and frequency were used to measure qualitative data. Data was analysed by SPSS.

Results

84 cases with thrombocytopenia of mean age 23.4 ± 12.1 years (range 7-81 years) were included in the study. There were 38 (45.2%) males and 46 (54.8%) females. There were 40 cases of immune thrombocytopenia. The sensitivity and specificity for PDW (59.1% and 43.1%, respectively), MPV (59.1% and 52.9%, respectively), and PLCR (50% and 52.9%, respectively) were found low to be used as screening tool for immune thrombocytopenia.

Conclusion

The MPV, PDW and PLCR has low sensitivity and specificity and therefore should not be used as reliable screening tool in giving preliminary diagnosis of the immune thrombocytopenia.