Significant differences between capillary and venous complete blood counts in the neonatal period

The normal capillary and venous hematologic values for neonates have not been defined clearly. It is well known that capillary blood has higher hemoglobin (Hb) and hematocrit (Hct) values than venous blood. In a recent study, we reported differences between capillary and venous complete blood counts (CBC) in healthy term neonates on day 1 of life. The aim of this study was to extend our previous investigation. Term neonates (n=141) were stratified into four groups by days of postnatal age: group 2 (day 7, n=38), group 3 (day 14, n=35), group 4 (day 21, n=32) and, group 5 (day 28, n=36). Data from our previous study were included in the statistical analysis as group 1 (day 1, n=95). A CBC and differential count were carried out on each capillary and venous sample drawn simultaneously. Within each group, the mean and standard deviation for each parameter in capillary and venous blood were calculated and then compared using the paired sample t-test. In all groups, the capillary blood samples had higher Hb, Hct, red blood cell (RBC), white blood cell (WBC), and lymphocyte counts. In each group, venous platelet counts were significantly higher than the corresponding capillary values. There was also a trend toward higher venous mean corpuscular volume, higher capillary polymorphonuclear leukocyte (PML) count and mean platelet volume in all groups. In both capillary and venous blood, Hb, Hct, RBC, MCV values and WBC, lymphocyte, PML counts decreased and platelet counts increased steadily during neonatal period. This study reveals that CBC parameters and differential counts may differ depending on the blood sampling used. The findings underline the importance of considering the sample source when using hematologic reference ranges for healthy or septic neonates. When interpreting results, the term 'peripheral blood' should be replaced with 'capillary blood' or 'venous blood' so that an accurate assessment can be made.     

Mean platelet volume in acute rheumatic fever

Acute rheumatic fever (ARF) is still an endemic disease, especially among school-aged children in developing countries. Mean platelet volume (MPV), which is commonly used as a measure of platelet size, indicates the rate of platelet production and platelet activation. We aimed to investigate MPV in children with ARF. The study population consisted of 40 children with ARF (32 patients with carditis and 8 patients without carditis) and 40 healthy control subjects. White blood cell (WBC) and platelet counts were significantly higher and MPV values were significantly lower in patients with ARF during the acute stage when compared to controls. Erythrocyte sedimentation rate (ESR) and C-reactive protein values significantly decreased in patients with ARF after the treatment when compared to baseline, whereas MPV values increased. MPV values were negatively correlated with ESR and WBC, and platelet counts. In conclusion, during the acute stage of ARF, MPV values were lower when compared to controls.     

Effective estimation of correct platelet counts in pseudothrombocytopenia using an alternative anticoagulant based on magnesium salt

Pseudothrombocytopenia remains a challenge in the haematological laboratory. The pre‐analytical problem that platelets tend to easily aggregate in vitro, giving rise to lower platelet counts, has been known since ethylenediamine‐tetra acetic acid EDTA and automated platelet counting procedures were introduced in the haematological laboratory. Different approaches to avoid the time and temperature dependent in vitro aggregation of platelets in the presence of EDTA were tested, but none of them proved optimal for routine purposes. Patients with unexpectedly low platelet counts or flagged for suspected aggregates, were selected and smears were examined for platelet aggregates. In these cases patients were asked to consent to the drawing of an additional sample of blood anti‐coagulated with a magnesium additive. Magnesium was used in the beginning of the last century as anticoagulant for microscopic platelet counts. Using this approach, we documented 44 patients with pseudothrombocytopenia. In all cases, platelet counts were markedly higher in samples anti‐coagulated with the magnesium containing anticoagulant when compared to EDTA‐anticoagulated blood samples. We conclude that in patients with known or suspected pseudothrombocytopenia the magnesium‐anticoagulant blood samples may be recommended for platelet counting.     

Haematological and biochemical reference intervals for infants and children in Gabon

Objectives To establish reference intervals for major haematological and biochemical parameters in Gabonese infants and children. Methods The reference sample population consisted of 226 healthy infants (4–9 weeks of age) and 185 healthy children (18–60 months of age). Basic red cell parameters as well as total and differential white blood cell counts were performed. Clinical chemistry parameters consisted of glutamate–pyruvic transaminase and creatinine, and total bilirubin was measured in children. Statistical analysis was based on the guidelines of the Clinical and Laboratory Standards Institute. Nonparametric methods were used to determine 95% reference limits and their 90% confidence intervals. Results Compared to European populations, values for several red cell parameters (haemoglobin, haematocrit, red blood cell count, mean corpuscular volume) were lower and platelet counts were higher. Eosinophils were higher in the older age group, most likely caused by intestinal helminths. Conclusions The study confirms the importance of establishing reference limits for local populations. The reference ranges could be used as a benchmark for similar populations in Central Africa.     

Haematological values from a Gambian cohort--possible reference range for a West African population

The objective of this study was to establish haematological reference ranges for the West African subregion using a Gambian cohort. We analysed full blood counts from 1279 subjects aged > or =1 year. Anthropometric and body composition measurements were performed. Haematological mean values, medians and 90% reference values were calculated and related to malnutrition in children and thinness and/or obesity in adults. Haemoglobin (Hb) and mean corpuscular volume (MCV) significantly increased with age (P < 0.00001). There were gender-related changes in Hb from 15 years of age (P = 0.001) and for MCV only in adults (P = 0.0002). Hb was significantly reduced in underweight and stunted children (P = 0.0001 and 0.0002, respectively) but was unaffected by thinness or obesity in adults. White blood cell (WBC) and platelet counts were highest under 5 years and declined significantly with age (P < 0.0001 and 0.0001). While, there were no gender-related differences with WBC, there were higher WBC counts in underweight (P = 0.0001) and stunted (P < 0.0001) children. Adult females had significantly higher mean platelet counts compared with males (P = 0.006). The mean and median values of haematological parameters in The Gambia are similar to other standards but the 90% reference range for each parameter encompasses lower values when compared with Western standards.     

Automated Optical Counting of Blood Platelets

We have evaluated the use of an opticalparticle counter to perform automatedplatelet counts on whole blood. Theerythrocytes were lysed by dilution ofwhole blood with 2 M urea and the remaining platelets and leukocytes wereenumerated by a darkfield microscopeoptical system that detects light diffractedby them. A suspension of fixed humanplatelets available commercially washighly satisfactory for standardization.The method gave accurate and reproducible platelet counts, comparable withthose of electronic particle counting onvenous blood and substantially morereliable platelet counts on thrombocytopenic and finger-puncture blood samples. We believe that errors resultingfrom the electronic method were causedby technical difficulties of sample handling and not to an intrinsic error in electronic counting. By using the automatedoptical method we found no significantdifference between the platelet counts ofcapillary and venous blood, althoughcapillary platelet counts had twice thevariability of venous counts. The opticaltechnique has important advantages overelectronic platelet counting, and itssuperiority appears to be due to the ability to count platelets in diluted wholeblood rather than in plasma. It shouldprove especially useful in performing thelarge numbers of platelet counts onthrombocytopenic and finger-punctureblood samples that are increasingly important for management of patients receiving chemotherapy.

Submitted on April 20, 1971 Revised on May 21, 1971 Accepted on May 25, 1971     

Thrombopoietin and mean platelet volume in coronary artery disease

BACKGROUND: Large platelets are shown to be hemostatically more active. It has been suggested that mean platelet volume (MPV) is increased during acute myocardial infarction (AMI) and unstable angina pectoris (USAP). However, the underlying mechanism of the phenomenon remains unclear. HYPOTHESIS: In this study, platelets, MPV, and thrombopoietin (TP) levels were investigated in patients with coronary artery disease (CAD) and healthy controls. METHODS: Twenty patients with AMI and 20 patients with USAP were included in this study. Seventeen healthy adult subjects served as controls. Venous blood samples of the subjects were drawn within 12 h after admission. Thrombopoietin levels were measured by ELISA and platelet counts and MPV were assayed by autoanalyzer. RESULTS: Patients with AMI and USAP had higher platelet counts than those in the control group. Although the platelet counts were slightly higher in AMI than in USAP, this did not reach statistical significance. Mean platelet volume and levels of TP were found to be elevated in patients with AMI and USAP compared with control subjects (p < 0.001). Thrombopoietin levels were higher in AMI than USAP, but this was not statistically significant. There was a positive correlation between TP levels and MPV values (p < 0.05). CONCLUSION: Increased TP levels may increase both platelet counts and platelet size, resulting in hemostatically more active platelets, which may contribute to the development and progression of CAD.     

Automated counting of platelets on the Bayer ADVIA 120 analyser.

Precise counting of platelets is difficult particularly in the low thrombocytopenic range or when large platelets exist. The recently available Bayer ADVIA 120 analyser uses a method of counting platelets based on two dimensional laser light scatter. We have evaluated this technique on an analysis of 217 peripheral blood samples and found significant differences in platelet counts compared with values obtained by impedance technology, when the causes of thrombocytopenia were due to peripheral platelet consumption. Moreover, such differences were more marked in those samples from severely thrombocytopenic individuals with large platelets on the blood film. These differences, which warrant further study, may have significant implications for the management of patients with very low platelet counts.     

Evaluation of the Use of a Platelet-Counting Tool in Plateletpheresis

OBJECTIVE: For years, blood transfusion centers in Taiwan have used the Quantitative Buffy Coat (QBC(R)) Hematology System for platelet counts on capillary blood samples in the laboratory screening of apheresis donors. The system has not been evaluated for the prediction of yields in plateletpheresis. Methods : The QBC instrument was evaluated for reproducibility of platelet counts and compared with five electronic cell counters. We also collected both capillary and venous blood from voluntary donors before donation and counted platelets, comparing the QBC system and an electronic blood cell counter (Sysmex K1000). The correlation between donors' predonation platelet counts and plateletpheresis yields was analyzed. RESULTS: The R values for platelet counts between the QBC Hematology System and other electronic counters are lower (0.759-0. 890) than among the electronic counters (0.929-0.973). The mean capillary platelet count and the mean venous platelet count were 241. 9+/-50.3x10(3)/microl and 233.2 +/-47.9x10(3)/microl by the QBC system, and 244.9+/-54.1x10(3)/microl and 218.9+/-46.5x10(3)/microl by the Sysmex K1000, respectively. Linear regression analysis showed that platelet yields correlated well with donors' predonation platelet counts using the Sysmex K1000 counter (R = 0.777- 0.890, p<0.001), but not with the QBC system (R = 0.326 approximately 0.755, p<0.05). CONCLUSION: The QBC Hematology System is not accurate enough to determine predonation platelet counts that are to be used for calculating the number of processing cycles for plateletpheresis.     

Automated counting of platelets on the Bayer ADVIATTMM 120 analyser

Precise counting of platelets is difficult particularly in the low thrombocytopenic range or when large platelets exist. The recently available Bayer ADVIA^TM 120 analyser uses a method of counting platelets based on two dimensional laser light scatter. We have evaluated this technique on an analysis of 217 peripheral blood samples and found significant differences in platelet counts compared with values obtained by impedance technology, when the causes of thrombocytopenia were due to peripheral platelet consumption. Moreover, such differences were more marked in those samples from severely thrombocytopenic individuals with large platelets on the blood film. These differences, which warrant further study, may have significant implications for the management of patients with very low platelet counts.     

Plasma levels of beta-thromboglobulin and platelet factor 4 in relation to the venous platelet concentration

The plasma levels of beta-thromboglobulin (beta-TG) and platelet factor 4 (PF-4) were determined in patients with various hematologic malignancies, and the results were related to simultaneously determined venous platelet counts. All studied patients were in a steady state. The plasma beta-TG concentrations were determined on 69 occasions and the values ranged from 0 to 82 ng/ml. In 33 instances, the venous platelet count was <25 x 10 (9/1) and in two thirds of these samples beta-TG was undedectable. The highest values for plasma beta-TG were found in patients with the highest venous platelet counts. A highly significant correlation (r=0.77, p <0.001) between the values for plasma beta-TG and venous platelet count was present. The plasma concentrations for PF-4 ranged from 0 to 50 ng/ml. Similarly, there was a highly significant relationship (r=0.78, p<0.001) between the values for PF-4 and venous platelet concentration. We conclude, if the plasma levels of beta-TG and PF-4 are used as markers of platelet activation in vivo, it is necessary to simultaneously consider the platelet concentration in the collected blood.     

Platelet activation in the Dutch haemocytometry quality assessment programme: correlation between P-selectin expression and variation in platelet count

Abstract: Since 1990, our laboratory has prepared a set of 8 fresh whole blood samples for use in a countrywide quality assessment (QA) programme. The samples are intended as external controls for haemocytometry analysers. These samples are of 8 different haematocrit levels and each one is prepared from a single donor. About 210 laboratories participate in this QA programme. From the start of this programme large interlaboratory variations in platelet counts were encountered in some of the samples. This variability was much higher than would be expected and was independent of the platelet count of the samples. The main cause was thought to be formation of platelet aggregates. The aim of the present study was to find a parameter that can predict a high interlaboratory variation in the QA programme. Therefore we investigated the initial platelet activation status in the donors and the activation status of platelets in the prepared QA blood. As a marker for platelet activation P-selectin expression on the platelets was measured using flow cytometry. During 5 rounds of the QA programme we found a good correlation of r = 0.53 (p < 0.001) between P-selectin expression on platelets in the reconstituted QA blood and the interlaboratory platelet count variability. We conclude that P-selectin expression in the prepared QA blood is an important parameter to exclude samples that lead to high CVs of platelet counts in the QA programme.     

Platelet counts in children with iron deficiency anemia.

Platelet count was evaluated in 30 children with iron deficiency anemia. It was found elevated when compared with 40 normal controls. No significant difference was found between the platelet counts in patients with hemoglobin levels higher or lower than 7 g/dl. Although no relation was observed between platelet count and transferrin saturation, it was correlated with serum iron values. After oral and/or parenteral iron therapy platelet count decreased insignificantly, while reticulocytes were found to be increased.     

Haematological reference ranges for schoolchildren

There are few reports of reference ranges for haematological values in school age children and most studies extend over a small age range or have excluded a considerable proportion of the study population in an effort to omit those with haemoglobinopathies or anaemia. Blood samples from 2135 children aged 4–19 years, from randomly selected schools, were analysed by automated counter. Reference ranges for red cell, white cell and platelet indices are provided from the results. Median haemoglobin and red blood cell count values for girls and boys rose together with increasing age, up to 12 years, but then diverged. Girls had a higher platelet count than boys. Mean platelet volume rose with age and was inversely related to the platelet count. Plateletcrit fell with age but in girls there was a peri-pubertal peak. Total leucocyte count fell with age. The upper limits for total leucocyte count in this study are approximately 2×10⁹ lower than those quoted in modern haematology textbooks. Lymphocyte, eosinophil and basophil counts fell with age with little difference between the sexes. Neutrophil and monocyte counts were similar for younger girls and boys but diverged in the older children with the older girls having higher values than boys.     

JAK2(V617F): Prevalence in a large Chinese hospital population

Recently, the JAK2(V617F) mutation was found in patients with myeloproliferative disorders (MPDs), including most with polycythemia vera (PV). The mutant JAK2 has increased kinase activity, and it was shown to be pathogenic in mouse models. Herein, we analyzed blood samples randomly collected from a clinical laboratory. Surprisingly, as many as 37 samples from a total of 3935 were found positive for the JAK2 mutation. However, only one of these samples had blood test results indicative for probable PV, but several had nonhematologic diseases. On average, samples with the mutation had normal red cell counts but significantly higher white blood cell and platelet counts, although most were within the normal range. The data suggest that the JAK2(V617F) mutation is apparently much more common than MPDs. Its occurrence may be a prelude to full blood cell abnormalities and other diseases, but it cannot by itself diagnose MPDs.     

Quantitative detection of platelet aggregates in whole blood without fixation

Platelet counting detects lesser degrees of platelet aggregation than conventional aggregometry. In order to prevent progressive platelet aggregation or disaggregation after sampling it is customary to fix blood samples. However fixation may introduce other artefacts. We first compared stability of platelet counts in EDTA-, citrate- and r-hirudin-anticoagulated blood from healthy volunteers. Second, the stability of platelet counts in unfixed EDTA- and hirudin-anticoagulated blood was compared with glutaraldehyde-fixed blood in the same anticoagulants. Third, the effect of in vivo heparin administration on platelet counts in EDTA- and hirudin-anticoagulated blood was studied. Platelet counts within 2 h of collection were significantly higher in EDTA- than in hirudin- or citrate-anticoagulated blood (P = 0.002 vs. hirudin and P = 0.001 vs. citrate). Twenty-four hour counts in hirudin and EDTA were unchanged (P = 0.3 and P = 0.2, respectively, vs. earlier counts). Counts in citrate increased significantly (P = 0.007; n = 10). Platelet counts in fixed blood did not differ significantly from those in unfixed blood. Heparin administered for cardiopulmonary bypass reduced platelet counts in hirudin-anticoagulated blood from (mean +/- 1 standard deviation) 180 +/- 45 to 162 +/- 30 x 10(9) l-1 (P = 0.01; n = 14), without significantly lowering counts with EDTA-anticoagulation, consistent with increased platelet aggregation. Hirudin and EDTA provided stable platelet counts, suggesting that fixation is unnecessary.     

Functional and Morphological Studies of Platelet Reactivity with Vessel Wall Subendothelium in Chronic Myeloproliferative Disease

S ummary . Mechanisms of thrombus formation in myeloproliferative disease were studied using a technique which visualized platelet-vessel wall interactions under physiological conditions of blood flow. Whole blood from four patients with chronic myelogenous leukaemia and three with thrombocythaemia were pumped through perfusion chambers containing de-endothelialized artery segments. Platelet reactivity with vessel walls (thrombus formation) was measured in sections of vessels by light microscopy and quantitative morphometric analysis. Five patients produced platelet reactivity values of 130-258% of controls while two gave decreased values. The two highest platelet reactivity values occurred in samples with elevated platelet counts and normal haematocrits. In contrast, when anti-platelet drugs were administered to three patients with high platelet counts, reactivity values decreased to 11-34% of controls. Clinical correlations revealed that patients with highest platelet reactivity values (165-258%) were those subjects who also exhibited thrombotic or haemorrhagic complications. Thus absolute platelet count and haematocrit may be major determinants in predicting these complications. Qualitative evaluations of thrombus formations by light and electron microscopy provide further evidence that platelets in myeloproliferative disease also possess qualitative abnormalities.     

Quantitative detection of platelet aggregates in whole blood without fixation

Platelet counting detects lesser degrees of platelet aggregation than conventional aggregometry. In order to prevent progressive platelet aggregation or disaggregation after sampling it is customary to fix blood samples. However fixation may introduce other artefacts. We first compared stability of platelet counts in EDTA-, citrate- and r-hirudin-anticoagulated blood from healthy volunteers. Second, the stability of platelet counts in unfixed EDTA- and hirudin-anticoagulated blood was compared with glutaraldehyde-fixed blood in the same anticoagulants. Third, the effect of in vivo heparin administration on platelet counts in EDTA- and hirudin-anticoagulated blood was studied. Platelet counts within 2 h of collection were significantly higher in EDTA than in hirudin- or citrate-anticoagulated blood ( P =0.002 vs. hirudin and P =0.001 vs. citrate). Twenty-four hour counts in hirudin and EDTA were unchanged ( P =0.3 and P =0.2, respectively, vs. earlier counts). Counts in citrate increased significantly ( P =0.007; n =10). Platelet counts in fixed blood did not differ significantly from those in unfixed blood. Heparin administered for cardiopulmonary bypass reduced platelet counts in hirudin-anticoagulated blood from (mean +/-1 standard deviation) 180+/-45 to 162+/-30 x 10 9 l -1 ( P =0.01; n =14), without significantly lowering counts with EDTA-anticoagulation, consistent with increased platelet aggregation. Hirudin and EDTA provided stable platelet counts, suggesting that fixation is unecessary.     

Age-related changes in thrombopoietin in children: reference interval for serum thrombopoietin levels

We studied thrombopoietin (TPO, Mpl ligand) values using a sensitive ELISA in 254 serum samples obtained from disease-free children and adult volunteers. TPO was detected in all samples, and its values ranged widely from 0.25 to 9.18 fmol/ml. When analysed by dividing the subjects into 11 age groups, the mean TPO levels from birth to 1 month of age were increased (3.73-5.92 fmol/ml). The highest values were found 2 d after birth; TPO levels then gradually decreased to adult levels (0.83 fmol/ml). The relationship between TPO values and platelet counts was not significant in all subjects (r = 0.27) or in children alone (r = 0.12). In children > 1 month of age a 95% reference interval for serum TPO values was determined from 0.58 to 3.27 fmol/ml. A significant correlation was found between TPO values in serum and plasma; serum TPO values = -0.257 + 4.039 x plasma TPO values (r = 0.951, P < 0.001, n = 22). This study is the first to report age-dependent changes in blood TPO levels throughout child development. Serum TPO values were significantly high up to 1 month of age and were correlated with plasma TPO levels.     

Increased platelet activation in young patients with prehypertension

Mean platelet volume (MPV) and sP-selectin levels are considered as indicators of platelet activation. In this study, we assessed platelet activation in prehypertensive patients by comparing MPV and sP-selectin levels of these patients with healthy conrols. The study population consisted of 25 newly diagnosed prehypertensive individuals (18 men, mean age = 34 ± 6 y) and 25 healthy control subjects (16 men, mean age = 33 ± 6 y) eligible for the current study. Blood pressure (BP) , lipid profile, plasma glucose, HOMA-IR values, sP-selectin levels, platelet counts, and MPV were measured in both groups. Other than systolic blood pressure (SBP) and diastolic blood pressure (DBP), baseline demographic characteristics of both groups were similar. No significant difference was found between the platelet counts of the two groups. Despite comparable platelet counts, platelet activation parameters were found significantly higher in the prehypertensives. Prehypertensives had larger a MPV value compared to that of the control group (8.24 ± 0.46 fl vs. 7.70 ± 0.64 fl; P = 0.001) and plasma sP-selectin levels were also significantly higher in the prehypertensive patients (163.60 ± 41.21 ng/ml vs. 132.80 ± 36.46; P = 0.007). Spearman correlation analysis revealed moderate positive correlation between SBP and platelet activation parameters (for SBP and MPV, r = 0.60, p = 0.001; for SBP and sP-selectin r = 0.51, p = 0.009). Prehypertension causes platelet activation as evidenced by increased MPV and plasma sP-selectin levels. Increased platelet activation might be related to increased vascular thrombotic risk in those patients.