Reference intervals of reticulated platelets and other platelet parameters and their associations

Evaluation of a novel moving threshold gating strategy for assessment of reticulated platelets in dogs using the ADVIA 2120 analyzer

BACKGROUND

A novel method using a moving threshold (r-PLTmt) to determine canine r-PLTs (reticulated platelets) has been introduced for ADVIA 2120 software v6.11.7.

OBJECTIVES

We aimed to evaluate absolute (ar-PLTmt) and percent (%r-PLTmt) prior to and after visual inspection of scattergrams (ar-PLTmtv, %rPLTmtv) compared with flow cytometry (flow) and to determine reference intervals (RIs) in 120 dogs.

METHODS

For method comparison, 42 blood samples of healthy and thrombocytopenic dogs were included. Calculation of Spearman's rho, Bland-Altman, and Passing-Bablok analysis was performed. Coefficients of variation (CVs) were determined for three concentration levels.

RESULTS

Moderate correlations between %r-PLTmt and %r-PLTmtv (r_s 0.75-0.76) were seen compared with flow cytometry. The CV for medium %r-PLTs counts assessed with flow cytometry was 12.9%. Comparable CVs were obtained for ar-PLTmt (14.4%) and %r-PLTmt (15.7%), and ar-PLTmtv and %r-PLTmtv (10.9% and 12.9%, respectively). At low and high concentration levels, CVs for % and absolute r-PLTmt/rPLTmtv ranged between 23%-30% and 15%-20%. In patients with microcytic hypochromic erythrocytes, CVs for ar-PLTmt and %r-PLTmt were 36%-66%. Visual inspection of scattergrams resulted in a marked decrease in CV ranging between 15% and 20%. A proportional bias of 10.8% between %r-PLTmt and flow cytometry became lower (9.7%) after visual validation of scattergrams. Passing-Bablok analysis showed proportional and constant error. RIs for r-PLTmt and r-PLTmtv were 0.2%-3.8% and 0.6-10.2 × 10⁹ /L and 0.3%-4.5% and 1.1-10.3 × 10⁹ /L, respectively. Median values for %r-PLTmtv were higher in young adults (≤2 years) than in older dogs (P = 0.03).

CONCLUSIONS

r-PLTmt and r-PLTmtv were moderately correlated with flow cytometry. Visual inspection of scattergrams is recommended.

Sex differences at the platelet-vascular interface

Platelets are multifunctional cells that ensure the integrity of the vascular wall and modulate the immune response at the blood/vascular interface. Their pathological activation results in both thrombosis and inflammation and implicates them in the pathogenesis of vascular disease. Vascular diseases are sexually dimorphic in terms of incidence, clinical presentation, outcome, and efficacy of anti-platelet therapy. We here provide an overview of what is known about the role of platelets in the initiation and progression of vascular diseases and summarize what is known about the sex differences in platelet reactivity and in the thromboinflammatory mechanisms that drive these diseases, with a particular focus on atherosclerosis, obstructive and non-obstructive coronary artery disease, and ischemic stroke. Understanding the sex differences at the platelet-vascular interface is clinically relevant as it will enable: (1) to design new therapeutic strategies that prevent the detrimental effects of the immune-modulatory function of platelets taking sex into account, and (2) to evaluate if sex-specific anti-platelet drug regimens should be used to reduce the risk not only of thrombosis but also of vascular disease progression.

Immature platelet fraction in rheumatoid arthritis with interstitial lung disease

BACKGROUND

Platelets have an effect on the hemostatic defense of the lung. Immature platelet fractions (iPF) reflects the number of young platelets containing ribonucleic acid in the circulation and real-time production. Information about their roles in rheumatic diseases is limited and there are no studies on iPF in RA with interstitial lung disease (ILD). Our aim is to investigate the association between the iPF level and occurrence of ILD in RA and the correlation of iPF with disease activity in general or only in RA with ILD.

METHODS

The study included 50 RA patients without ILD, 33 RA patients with ILD, and 30 healthy controls. Demographic data, Disease Activity Score 28 (DAS28), autoantibodies, and iPF were evaluated. ILD was diagnosed by using high-resolution computed tomography with clinical findings and chest X-ray. The samples were analyzed for complete blood count with platelet indices included, on Mindray BC-6800 hematology analyzer, Hamburg, Germany.

RESULTS

iPF levels were higher in RA patients with ILD compared to healthy controls and RA patients without ILD. A weakly positive correlation between DAS28 with iPF was found in all RA patients. iPF levels were found as 2.85 to detect ILD with 66.7% sensitivity and 65% specificity.

CONCLUSIONS

Our results showed that the iPF was detected higher in RA with ILD compared to RA without ILD. iPF, a routine cheap and easy test during hemogram, can provide important information in terms of disease activity and lung involvement in RA.

Role of Reticulated Platelets in Cardiovascular Disease

Human platelets differ considerably with regard to their size, RNA content and thrombogenicity. Reticulated platelets (RPs) are young, hyper-reactive platelets that are newly released from the bone marrow. They are larger and contain more RNA compared to older platelets. In comparison to more mature platelets, they exhibit a significantly higher thrombogenicity and are known to be elevated in patients with an increased platelet turnover such as, diabetics and after acute myocardial infarction. Several studies have shown that RPs correlate with an insufficient antiplatelet response to aspirin and specific P2Y₁₂ receptor inhibitors. In addition, RPs are promising novel biomarkers for the prediction of adverse cardiovascular events in cardiovascular disease. However, the reason for RPs intrinsic hyper-reactivity and their association with ischemic events is not completely understood and the biology of RPs is still under investigation. We here present a structured review of preclinical and clinical findings concerning the role of RPs in cardiovascular disease.

Platelet Subtypes in Inflammatory Settings

In addition to their essential role in hemostasis and thrombosis, platelets also modulate inflammatory reactions and immune responses. This is achieved by specialized surface receptors as well as secretory products including inflammatory mediators and cytokines. Platelets can support and facilitate the recruitment of leukocytes into inflamed tissue. The various properties of platelet function make it less surprising that circulating platelets are different within one individual. Platelets have different physical properties leading to distinct subtypes of platelets based either on their function (procoagulant, aggregatory, secretory) or their age (reticulated/immature, non-reticulated/mature). To understand the significance of platelet phenotypic variation, qualitatively distinguishable platelet phenotypes should be studied in a variety of physiological and pathological circumstances. The advancement in proteomics instrumentation and tools (such as mass spectrometry-driven approaches) improved the ability to perform studies beyond that of foundational work. Despite the wealth of knowledge around molecular processes in platelets, knowledge gaps in understanding platelet phenotypes in health and disease exist. In this review, we report an overview of the role of platelet subpopulations in inflammation and a selection of tools for investigating the role of platelet subpopulations in inflammation.

Impact of Red Cell and Platelet Distribution Width in Patients of Medical Intensive Care Unit

Introduction The red blood cell distribution width (RDW) is a measurement of variations in the size of red blood cells. As the width increases, the rate of mortality also increases, although the reason for it is still not known. On the other hand, platelet distribution width (PDW) is also useful in predicting morbidity and mortality in sepsis and other critically ill patients. In our study, we planned to study the impact of both RDW and PDW and evaluate their prognostic importance with outcome in patients admitted in medicine intensive care unit (MICU). Material and Method In these cross-sectional observational studies, 1,300 patients were included who were admitted in MICU. Critically ill patients were defined on the basis of qSOFA score greater than 2. PDW and RDW were obtained from Coulter report of complete blood count. Parameters included in Acute Physiology and Chronic Health Evaluation (APACHE) IV scores were taken and APACHE IV score was calculated. Correlation of RDW and PDW with outcomes such as length of ICU stay, use of mechanical ventilator, and discharge/death was done. Result The mean RDW (%) for the entire study population was 15.17 ± 3.01. The RDW (%) was significantly on the higher side in patients who succumbed to the disease as compared with the patients who were discharged. The correlation between the length of ICU stay (days) and RDW (%) was moderately positive and was significant (rho = 0.37, p ≤ 0.001). The correlation between the length of ICU stay (days) and PDW (%) was moderately positive and was significant (rho = 0.5, p ≤ 0.001). Conclusion RDW and PDW were found as significant indicators for period of stay in ICU, requirement for mechanical ventilation, and mortality rate in patients admitted to ICUs. As these are simple, easy to conduct, universally available tests, they can be regularly incorporated in patients admitted in ICUs.

Proteome and functional decline as platelets age in the circulation

BACKGROUND

Platelets circulate in the blood of healthy individuals for approximately 7-10 days regulated by finely balanced processes of production and destruction. As platelets are anucleate we reasoned that their protein composition would change as they age and that this change would be linked to alterations in structure and function.

OBJECTIVE

To isolate platelets of different ages from healthy individuals to test the hypothesis that changes in protein content cause alterations in platelet structure and function.

METHODS

Platelets were separated according to thiazole orange fluorescence intensity as a surrogate indicator of mRNA content and so a marker of platelet age and then subjected to proteomics, imaging, and functional assays to produce an in-depth analysis of platelet composition and function.

RESULTS

Total protein content was 45 ± 5% lower in old platelets compared to young platelets. Predictive proteomic pathway analysis identified associations with 28 biological processes, notably higher hemostasis in young platelets whilst apoptosis and senescence were higher in old platelets. Further studies confirmed platelet ageing was linked to a decrease in cytoskeletal protein and associated capability to spread and adhere, a reduction in mitochondria number, and lower calcium dynamics and granule secretion.

CONCLUSIONS

Our findings demonstrate changes in protein content are linked to alterations in function as platelets age. This work delineates physical and functional changes in platelets as they age and serves as a base to examine differences associated with altered mean age of platelet populations in conditions such as immune thrombocytopenia and diabetes.

Platelet reticulated forms, size indexes, and functional activity. Interactions in healthy volunteers

Reticulated platelets (RP) are young, functionally active platelet forms which are detected by RNA staining. Their content in the circulation reflects the intensity of bone marrow thrombocytopoesis. The aim of this study was to assess in healthy volunteers the relationship between RP percentage and platelet size and activity. RP were quantitated by thiazole orange staining using flow cytometry. Platelet size indexes included mean platelet volume (MPV), platelet large cell ratio (P-LCR) measured in a Coulter type hematological analyzer and forward scattering (FSC) measured in a flow cytometer. Platelet functional activity was evaluated by expression of activated glycoprotein (GP) IIb-IIIa (PAC-1 antibody binding) and P-selectin with the use of flow cytometry. Platelets were activated by thrombin receptor activating peptide (TRAP) (10 and 1 µM) and ADP (20 and 2.5 µM). The percentage of RP in healthy volunteers varied from 2.9% to 23.8% (mean ± SD ‒ 11.7 ± 4.7%, n = 99) and correlated with all platelet size indexes: MPV, P-LCR and FCS (r from 0.452 to 0.529, p < .001, n = 87-99). On average, RP were distributed at a ratio of 9:1 between 50% subpopulations of large and small platelets according to their FSC index. Expression of GP IIb-IIIa activated form correlated with RP percentage and platelet size indexes when platelets were activated by TRAP and ADP at both applied concentrations (r from 0.309 to 0.560, p from 0.014 to < 0.001, n = 50-62). P-selectin expression correlated with RP percentage and platelet size indexes when platelets were activated by 10 µM TRAP inducing maximum expression of this activation marker (r from 0.332 to 0.556, p from 0.008 to < 0.001, n = 65), but not by weaker agonists: 1 µM TRAP, 20 and 2.5 µM ADP (r < 0.3, n = 54-66). Thus, high RP content in healthy volunteers is associated with increased platelet size and activity in the whole platelet population.

Immature Platelet Fraction in Rheumatoid Arthritis with Interstitial Lung Disease

BACKGROUND

Platelets have an effect on the hemostatic defense of the lung. Immature platelet fractions (iPF) reflects the number of young platelets containing ribonucleic acid in the circulation and real-time production. Information about their roles in rheumatic diseases is limited and there are no studies on iPF in RA with interstitial lung disease (ILD). Our aim is to investigate the association between the iPF level and occurrence of ILD in RA and the correlation of iPF with disease activity in general or only in RA with ILD.

METHODS

The study included 50 RA patients without ILD, 33 RA patients with ILD, and 30 healthy controls. Demographic data, Disease Activity Score 28 (DAS28), autoantibodies, and iPF were evaluated. ILD was diagnosed by using high-resolution computed tomography with clinical findings and chest X-ray. The samples were analyzed for complete blood count with platelet indices included, on Mindray BC-6800 hematology analyzer, Hamburg, Germany.

RESULTS

iPF levels were higher in RA patients with ILD compared to healthy controls and RA patients without ILD. A weakly positive correlation between DAS28 with iPF was found in all RA patients. iPF levels were found as 2.85 to detect ILD with 66.7% sensitivity and 65% specificity.

CONCLUSIONS

Our results showed that the iPF was detected higher in RA with ILD compared to RA without ILD. iPF, a routine cheap and easy test during hemogram, can provide important information in terms of disease activity and lung involvement in RA.

Reticulated Platelets-Which Functions Have Been Established by In Vivo and In Vitro Data?

Reticulated platelets (RP) are the youngest platelet fraction released into the circulation. These immature platelets have increased RNA content, a larger cell volume, more dense granules, higher levels of surface activation markers and are thought to be more reactive compared to their mature counterparts. RP have been associated with cardiovascular disease, diabetes and increased mortality. Yet only a few animal studies investigating RP have been conducted so far and further investigations are warranted. Established methods to count RP are flow cytometry (staining with thiazole orange or SYTO13) or fully automated hematology analyzers (immature platelet fraction, IPF). IPF has been established as a diagnostic parameter in thrombocytopenia, cardiovascular disease and, in particular, the response to antiplatelet therapy. This review seeks to provide an overview of the key features of RP as well as preanalytical and analytical aspects that need to be considered when working with this platelet population.

Platelets parameters in septic shock: clinical usefulness and prognostic value

: Septic shock is a common cause of admission in the ICUs. Despite tremendous improvement in the management modalities, mortality remains high. Early diagnosis and prompt resuscitation are required to improve prognosis. Therefore, identifying a biomarker that could reveal the sepsis at its earlier stage is of paramount importance. In this regards, platelet parameters, such as mean platelet volume, immature platelet fraction and platelet-derived microparticles have been investigated as possible sepsis biomarkers. In fact, haemostasis disturbances are one of the hallmark of septic shock where platelets play a pivotal role in orchestrating the inflammatory response of the host. Moreover, these parameters could have a prognostic value as the severity of the multiorgan dysfunction is correlated with the inflammatory reaction.

Immature Platelet Dynamics in Immune-Mediated Thrombocytopenic States

A major challenge encountered by clinicians is differentiating presentations characterized by significant thrombocytopenia due to overlapping clinical symptoms and signs in the setting of ambiguous laboratory results. Immature platelets represent the youngest platelets that can be measured in peripheral blood by current hematology analyzers. These young platelets are larger, with higher RNA content recently released from the bone marrow. Thrombocytopenic presentations caused directly or indirectly by immune responses can lead to compensatory bone marrow responses seeking to normalize the platelet count; thus obtaining absolute immature platelet counts may be informative while triaging patients. Over the last decade, their use has expanded beyond being an early biomarker of bone marrow reconstitution post-hematopoietic stem cell transplantation to being used to establish bone marrow responses to infection and thrombocytopenias due to immune etiologies. Its accessibility as part of more detailed platelet indices obtained with routine laboratories makes it a promising option to understand the bone marrow's real-time response to disease states characterized by thrombocytopenia. This review will look at the immature platelet count as a biomarker, while presenting current attempts trying to understand how it could be used in thrombocytopenias occurring secondary to a given immune etiology.

Capillary blood reference intervals for platelet parameters in healthy full-term neonates in China

Background

No consensus has been reached on capillary blood reference intervals for platelet parameters in full-term neonates. We aimed to establish neonatal capillary blood reference intervals for platelet parameters and evaluate influences of sex, gestational age and postnatal age on platelet parameters.

Methods

This study was a prospective investigation and implemented in 594 healthy full-term neonates from 12 to 84 h of age, using SYSMEX XN-9000 haematology automatic analyser by means of capillary blood. Reference intervals for platelet parameters were defined by an interval of 2.5th − 97.5th percentiles.

Results

Capillary reference interval for platelet count was (152–464) × 10⁹/L. No significance was found between sex-divided reference intervals for platelet parameters. The values of platelet count changed minimally across gestational age (37–41 weeks) and postnatal age (12–84 h). Reference intervals for other platelet parameters were affected by these factors to a different extent.

Conclusions

We established capillary blood reference intervals for platelet parameters in the first days after birth of full-term neonates in China.

Influence of different methods and anticoagulants on platelet parameter measurement

Platelets are the smallest and perhaps the most versatile components of human blood. Besides their role in coagulation and the maintenance of vascular integrity, they are involved in many physiological processes, ranging from immune response and leukocyte recruitment to the production of antimicrobial peptides and immune-suppressive factors like TGF-β. These versatile abilities make platelets interesting for researchers from different disciplines. However, beside profound investigation into platelets’ physiological role, there is a need for correct, standardized and thus reproducible quantification of platelet parameters. Mean platelet volume (MPV) is a widespread prognostic marker for several conditions, such as, acute coronary syndrome, chronic kidney disease and liver cirrhosis. Platelet activation is regarded as a marker for inflammatory processes, for example in autoimmune diseases such as type-1 diabetes, systemic lupus erythematosus and rheumatoid arthritis. The monitoring of platelet function is relevant for patients receiving antiplatelet medication. Platelet parameter measurement is affected by the choice of in vitro anticoagulant, the measurement technology and the time delay after sampling. This review focuses on the pre-analytical variability that arises as a result of the use of different in vitro anticoagulants and analyzer technologies when determining platelet parameters, since, even approximately 180 years after the discovery of platelets, there is still no standardized procedure.

Platelet parameters in Chinese older adults with metabolic syndrome

PURPOSE

We aimed to examine the associations of platelet parameters with the presence of metabolic syndrome in community-dwelling older Chinese adults.

METHODS

Study sample was from the Weitang Geriatric Diseases Study, which included 4338 individuals aged 60 years or above. The mean age of the participants was 68 years. Metabolic syndrome was defined based on the Adult Treatment Panel III criteria. Platelet parameters were assessed using an automated hematology analyzer. Multiple logistic regression models were fitted to examine relationships between the platelet parameters and the presence of metabolic syndrome after adjusting for potential confounders.

RESULTS

The adjusted odds ratio (95% CI) of metabolic syndrome for the highest quartile of platelet parameters (platelet count, mean platelet volume, plateletcrit, platelet distribution width, platelet larger cell ratio) when compared to the lowest quartile were 1.32 (1.06, 1.64), 1.00 (0.81, 1.24), 1.37 (1.10, 1.71), 1.45 (1.14, 1.83), 1.11 (0.89, 1.39), respectively. Hypertension and diabetes modified the relationship between platelet distribution width and metabolic syndrome with the associations being significant in hypertensive and non-diabetic groups. The levels of platelet distribution width increased with the risk of metabolic syndrome in men but not in women.

CONCLUSION

The levels of platelet count, plateletcrit and platelet distribution width increased in older adults with metabolic syndrome, suggesting that these parameters may be useful biomarkers for further risk appraisal of metabolic syndrome in aged population.

Reticulated platelets and immature platelet fraction: Clinical applications and method limitations

So-called "reticulated" or "immature platelets," which are newly released into the circulation, are more reactive than mature platelets, contain more RNA, and can be counted using flow cytometry after staining with thiazole orange or using some fully automated hematology analyzers, albeit with numerical disagreement. This review provides an overview of the state of the art of available technology for measuring immature or reticulated platelets (RP) with preanalytical (time stability, biological variation), analytical (methods, imprecision), and postanalytical (reference range) limitations. We also analyzed the clinical conditions in which immature/RP can be considered a diagnostic or prognostic tool (ie, differential diagnosis of thrombocytopenia, recovery after bone marrow or stem cell transplantation, risk assessment in cardiovascular diseases, response to antiplatelet drugs). They might also be of clinical utility in other settings but with lower evidence. The lack of a specific reference method and universal control material, as well as dependency of results on the measurement technique used, calls for different reference intervals and compromises comparison between clinical studies carried out using different analytical methods. To obviate lack of agreement between methods, more specific RNA dyes are necessary and the impact of the platelet size on the fluorescence signal defined. In the harmonization age, also in nomenclature field, a new definition instead of "reticulated" or "immature" platelets would be useful, and "young platelets" might be a more appropriate definition taking into account both the age and the functionality of this platelet fraction.

Reticulated platelets – clinical application and future perspectives

Reticulated platelets are immature platelets freshly released from the bone marrow into the circulation and contain vestigial amounts of ribonucleic acid. Thus, they can serve as an indicator for the activity of thrombopoiesis. Despite the current lack of a standardized reference method, two types of hematology analyzers have incorporated a fully automated measurement of reticulated platelets. The “immature platelet fraction” (IPF; Sysmex XE-/XN-series) has some clinical utility in the differential diagnosis of thrombocytopenia. This is less clear for “reticulated platelets” (retPLT; Abbott CELL-DYN Sapphire/Alinity HQ). The usefulness of these parameters in the prediction of platelet recovery after chemotherapy or stem cell transplantation and as a decision aid for platelet transfusions has not been unequivocally confirmed. Recent findings have shown an association of reticulated platelets with an adverse risk in patients with coronary artery disease and stroke as well as resistance to anti-platelet therapy. Furthermore, a role of reticulated platelets for the prediction of sepsis was indicated. However, validation in larger prospective trials is necessary to establish the clinical benefit of reticulated platelets in these conditions. This review gives an overview of the available analytical methods and summarizes the current knowledge regarding the clinical application of reticulated platelets.

Effect of preanalytical and analytical variables on the clinical utility of mean platelet volume

BACKGROUND

The study endpoint was to analyze the effect of preanalytical (time, temperature, anticoagulant) and analytical (imprecision, correlation between volume and platelet concentration) variables on mean platelet volume (MPV). A further aim was to calculate in an adult population the reference intervals using the Sysmex XE-5000 analyzer. A critical evaluation was also made of the clinical utility of these parameters.

METHODS

Analyses of the above values were performed in duplicate in 170 healthy adults of both sexes: (1) within 30 min from collection, and (2) after 4 h. To evaluate stability over time, the value of the platelet parameters of 20 subjects were determined, a re-analysis being performed for a period of up to 24 h on samples maintained at room temperature and 4°C using either K2-EDTA or Na-citrate as anticoagulants.

RESULTS

The stability over time of MPV closely depends on the anticoagulant used, storage temperature and time interval between venipuncture and analysis. An inverse, non-linear correlation between MPV and platelet count was also found.

CONCLUSIONS

In view of their effect on MPV and other related indices, the preanalytical and analytical variables make them, little more than experimental.

Indirect methods for reference interval determination - review and recommendations

Reference intervals are a vital part of the information supplied by clinical laboratories to support interpretation of numerical pathology results such as are produced in clinical chemistry and hematology laboratories. The traditional method for establishing reference intervals, known as the direct approach, is based on collecting samples from members of a preselected reference population, making the measurements and then determining the intervals. An alternative approach is to perform analysis of results generated as part of routine pathology testing and using appropriate statistical techniques to determine reference intervals. This is known as the indirect approach. This paper from a working group of the International Federation of Clinical Chemistry (IFCC) Committee on Reference Intervals and Decision Limits (C-RIDL) aims to summarize current thinking on indirect approaches to reference intervals. The indirect approach has some major potential advantages compared with direct methods. The processes are faster, cheaper and do not involve patient inconvenience, discomfort or the risks associated with generating new patient health information. Indirect methods also use the same preanalytical and analytical techniques used for patient management and can provide very large numbers for assessment. Limitations to the indirect methods include possible effects of diseased subpopulations on the derived interval. The IFCC C-RIDL aims to encourage the use of indirect methods to establish and verify reference intervals, to promote publication of such intervals with clear explanation of the process used and also to support the development of improved statistical techniques for these studies.

Platelet populations and priming in hematological diseases

In healthy subjects and patients with hematological diseases, platelet populations can be distinguished with different response spectra in hemostatic and vascular processes. These populations partly overlap, and are less distinct than those of leukocytes. The platelet heterogeneity is linked to structural properties, and is enforced by inequalities in the environment. Contributing factors are variability between megakaryocytes, platelet ageing, and positive or negative priming of platelets during their time in circulation. Within a hemostatic plug or thrombus, platelet heterogeneity is enhanced by unequal exposure to agonists, with populations of contracted platelets in the thrombus core, discoid platelets at the thrombus surface, patches of ballooned and procoagulant platelets forming thrombin, and coated platelets binding fibrin. Several pathophysiological hematological conditions can positively or negatively prime the responsiveness of platelet populations. As a consequence, in vivo and in vitro markers of platelet activation can differ in thrombotic and hematological disorders.

Validated age-specific reference values for CSF total protein levels in children

OBJECTIVE

To define age-specific reference values for cerebrospinal fluid (CSF) total protein levels for children and validate these values in children with Guillain-Barré syndrome (GBS), acute disseminated encephalomyelitis (ADEM) and multiple sclerosis (MS).

METHODS

Reference values for CSF total protein levels were determined in an extensive cohort of diagnostic samples from children (<18 year) evaluated at Erasmus Medical Center/Sophia Children's Hospital. These reference values were confirmed in children diagnosed with disorders unrelated to raised CSF total protein level and validated in children with GBS, ADEM and MS.

RESULTS

The test results of 6145 diagnostic CSF samples from 3623 children were used to define reference values. The reference values based on the upper limit of the 95% CI (i.e. upper limit of normal) were for 6 months-2 years 0.25 g/L, 2-6 years 0.25 g/L, 6-12 years 0.28 g/L, 12-18 years 0.34 g/L. These reference values were confirmed in a subgroup of 378 children diagnosed with disorders that are not typically associated with increased CSF total protein. In addition, the CSF total protein levels in these children in the first 6 months after birth were highly variable (median 0.47 g/L, IQR 0.26-0.65). According to these new reference values, CSF total protein level was elevated in 85% of children with GBS, 66% with ADEM and 23% with MS.

CONCLUSION

More accurate age-specific reference values for CSF total protein levels in children were determined. These new reference values are more sensitive than currently used values for diagnosing GBS and ADEM in children.

Neutrophil to Lymphocyte Ratio and Mean Platelet Volume as Inflammatory Indicators in Systemic Lupus Erythematosus Nephritis

OBJECTIVES

This study aims to evaluate the role of neutrophil to lymphocyte ratio (NLR) and mean platelet volume (MPV) as activation and inflammatory markers in systemic lupus erythematosus (SLE) patients with nephritis.

PATIENTS AND METHODS

A total of 108 SLE patients (8 males, 100 females; mean age 35.3±10.2 years; range 16 to 64 years) including 78 patients with renal involvement (8 males, 70 females; mean age 33.9±10.6 years; range 16 to 64 years) (SLEn+ group) and 30 patients without renal involvement (30 females; mean age 39.1±8.2 years; range 22 to 55 years) (SLEn- group) were included in this retrospective study. All patients' clinical characteristics and laboratory data which include erythrocyte sedimentation rate, C-reactive protein, white blood counts, neutrophil counts, lymphocyte counts, platelet counts, and MPV levels were obtained from medical records. The laboratory data at the highest proteinuria periods of the patients with renal involvement were recorded.

RESULTS

Mean MPV (SLEn+ =9.1±2.2, SLEn- =7.9±1.2, p=0.001) and NLR (SLEn+ =5.9±5.9, SLEn- =2.6±2.5, p<0.001) values were significantly higher in lupus nephritis group. Besides, a positive correlation between NLR and C-reactive protein was found in lupus nephritis group (r=1.97, p=0.045). Based on receiver operating characteristic curve with area under the curve of 0.76, cutoff NLR value of 1.93 had 83% sensitivity and 54% specificity [95% confidence interval, 0.66-0.85] in differentiating SLE patients with or without nephritis.

CONCLUSION

Neutrophil to lymphocyte ratio and MPV may be discriminative for lupus nephritis. Also, NLR may be a predictor of lupus nephritis. Both MPV and NLR values may be affected by a great number of factors; therefore, further prospective studies are needed to evaluate the use of these parameters in SLE.

Impact of Atrial Fibrillation and Sinus Rhythm Restoration on Reticulated Platelets

OBJECTIVE

To assess the impact of nonvalvular atrial fibrillation (NVAF) and sinus rhythm restoration on the distribution of reticulated platelets (RPs), which are known to be associated with thrombotic propensity and have a greater predilection for thrombus participation.

PARTICIPANTS AND METHODS

The RP content was assessed by flow cytometry (thiazole orange/CD61) in 110 consecutive patients with NVAF before and 3 to 4 months after catheter ablation of the pulmonary veins. Results were compared with those of 55 age- and sex-matched controls with normal sinus rhythm.

RESULTS

The mean ± SD percentage of RPs was higher in patients with NVAF compared with controls (28.5%±7.3% vs 6.4%±5.3%; P<.001). The RP content did not vary by CHA2DS2-VASc score. After catheter ablation of the pulmonary veins, 63 patients were available for follow-up assessment. A significant reduction of RPs was observed compared with preintervention values (29.85%±7.1% vs 20.79%±7.6%; P<.001). During follow-up, 19% of patients (12 of 63) had confirmed AF recurrence. The mean ± SD percentage of RPs was higher in this group than in those without a recurrence (24.7%±6.5% vs 18.9%±7.5%; P=.01).

CONCLUSION

Nonvalvular atrial fibrillation affects the percentage of RPs, independent of the CHA2DS2-VASc score. After ablation, RP content dropped significantly. High RP content in patients with NVAF may explain the potential mechanism of thromboembolic complications and the lack of efficacy of currently available antiplatelet therapy for stroke prevention in this dysrhythmia.

Platelet function tests, independent of platelet count, are associated with bleeding severity in ITP

Immune thrombocytopenia (ITP) patients with similarly low platelet counts differ in their tendency to bleed. To determine if differences in platelet function in ITP patients account for this variation in bleeding tendency, we conducted a single-center, cross-sectional study of pediatric patients with ITP. Bleeding severity (assessed by standardized bleeding score) and platelet function (assessed by whole blood flow cytometry) with and without agonist stimulation was evaluated in 57 ITP patients (median age, 9.9 years). After adjustment for platelet count, higher levels of thrombin receptor activating peptide (TRAP)-stimulated percent P-selectin- and activated glycoprotein (GP)IIb-IIIa-positive platelets were significantly associated with a lower bleeding score, whereas higher levels of immature platelet fraction (IPF), TRAP-stimulated platelet surface CD42b, unstimulated platelet surface P-selectin, and platelet forward light scatter (FSC) were associated with a higher bleeding score. Thus, platelet function tests related to platelet age (IPF, FSC) and activation through the protease activated receptor 1 (PAR1) thrombin receptor (TRAP-stimulated P-selectin, activated GPIIb-IIIa, and CD42b), independent of platelet count, are associated with concurrent bleeding severity in ITP. These tests may be useful markers of future bleeding risk in ITP.

An elevated percentage of reticulated platelet is associated with increased mortality in septic shock patients

Microcirculatory changes and coagulation disturbances are thought to play a key role in sepsis. Some evidence suggests that the percentage of reticulated platelets (RP%) may be a valuable and cost-effective sepsis screening parameter. This was a prospective study in surgical patients to investigate the potential value of RP% as a predictor of mortality in septic shock patients.This was a prospective study conducted in a surgical critical care center of a Chinese tertiary care hospital. Consecutive septic shock patients were enrolled at admission. Age- and sex-matched non-septic patients were recruited as control patients. RP% was determined by flow cytometry in 68 septic shock patients and 68 controls.Compared with survivors, septic patients who died presented with a significantly higher RP% (P < 0.001). The area under the receiver-operating characteristic curve for the RP% association with mortality was 0.867 (95 % CI 0.780-0.953, P < 0.001). Kaplan-Meier survival curves showed that mortality risk was significantly different when patients were stratified based on RP% (P < 0.001). This association was preserved in a multi-logistic regression analysis that included clinical confounders (P < 0.014).This prospective study demonstrates that increased RP% identifies septic shock patients who have a high risk of death. RP% has the potential to act as a marker for patient stratification in future clinical trials.

Clinical applicability of reticulated platelets

BACKGROUND

Reticulated platelets (RPs), immature platelets newly released from the bone marrow into the circulation, have a high content of ribonucleic acid and are larger and more active in thrombus formation.

OBJECTIVE

This review compiles articles that evaluated RP in order to establish their clinical significance.

DISCUSSION

RPs increase when platelet production rises and decrease when production falls. As such, the measurement of circulating RPs allows the assessment of thrombocytopenia, i.e., bone marrow production or peripheral destruction.

CONCLUSION

RPs are a promising laboratory tool for evaluation of idiopathic thrombocytopenia (differentiating hypoproduction from accelerated platelet destruction), chemotherapy and after stem cell transplantation (predicting platelet recovery) and thrombocytosis (estimating platelet turnover). Additional randomized and well controlled clinical studies are required to clearly establish the significance of circulating RPs in other clinical conditions.