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PubMed1990

Platelet count, mean platelet volume and their relation to prognosis in cerebral infarction.

The study was performed on patients with ischaemic cerebral infarction in order to obtain information on serial changes of some platelet parameters and to test their prognostic significance. Platelet count, obtained within 48 h after cerebral infarction, was significantly lower than in the control group (213,611 +/- 65,652 mm-3 vs. 299,525 +/- 60,611 mm-3, P less than 0.001), reaching the normal level on the ninth day and thereafter. The mean platelet volume was significantly greater than in the controls (11.26 +/- 1.29 fl vs. 8.93 +/- 0.93 fl, P less than 0.001), and normalization generally occurred on the forty-fifth day. The mean platelet count was significantly lower in the patients who died than in those who survived (P less than 0.025 and P less than 0.05 respectively on the first to second and fourth day after infarction). The reduction of platelet count and the increase of mean volume appear to be related to an increased platelet consumption in the infarction area, associated with an in vivo platelet activation, as larger platelets are more responsive to platelet activity and aggregability tests. The lower mean platelet count observed in the patients who died suggests that the platelet value might be considered as a prognostic index of cerebral infarction.

Aged↗

PubMed1975

Platelet function in patients with high platelet counts.

Platelet function tests were done to ascertain whether they might have discriminatory significance in the differentiation of a myeloproliferative disorder from secondary thrombocytosis in a patient with an elevated platelet count. Amongst 14 subjects with polycythaemia vera and essential thrombocythaemia, significant abnormalities of platelet aggregation were the rule, while defective aggregation was unusual in 16 subjects with secondary thrombocytosis. Measurements of the bleeding time and of platelet factor 3 activity were of some value, but significant overlap was noted. Platelet function in four of five subjects with chronic myeloid leukaemia was essentially normal.

Adolescent↗

PubMed1986

Platelet count and platelet size in healthy Africans and West Indians.

Healthy subjects of African origin were found to have lower platelet counts than simultaneously studied healthy Caucasians. A similar reduction was found in a large group of West Indian females, though not in a small group of West Indian males. It is suggested that the lower platelet counts observed in Africans and West Indians may be partly environmental and partly genetic in origin. The mean platelet volume and platelet distribution width in the Africans and West Indians showed the same relationship with the platelet count as was found in Caucasians, so that the same nomograms can be used in all ethnic groups to assess whether there is deviation from normality.

Africa↗

PubMed1977

Chronic effect of smoking on platelet count and "platelet adhesiveness" in presumably healthy middle-aged men.

In 386 men aged 40-49 years the number of platelets was related to differences in smoking habits. "Platelet adhesiveness" (retention) was estimated by a glass bead filter method in 376 of these men. The estimation of "adhesiveness" was performed in native blood without anticoagulants at least 12 hr after the last cigarette smoked. A small but statistically highly significant increase in platelet count, in number of "adhesive platelets" and percentage of "adhesive platelets" was found in smokers as compared with non-smokers, the highest values being found in the heaviest smokers and vice versa. Such smoking-related changes in platelet count and reactiveness might unfavourably influence the tendency towards coronary thrombosis, and might in part explain the deleterious effects of smoking on coronary heart disease morbidity and mortality.

Adult↗

PubMed1999

Effects of asymptomatic abdominal aortic aneurysm on the soluble coagulation system, platelet count and platelet activation.

OBJECTIVES: the aim of the study was to determine the effects of infrarenal asymptomatic abdominal aortic aneurysm (AAA) on platelet count and activation. DESIGN: prospective clinical study in a University Department of Vascular Surgery. PATIENTS: one hundred and five patients with AAA. Thirty-two control patients with symptomatic carotid artery stenoses. METHODS: platelet count (PC), plasma glycocalicin levels, prothrombin ratio (PTR), activated partial thromboplastin time (APPT), fibrinogen and D-dimer were measured in 23 patients with AAA and 16 control patients with symptomatic carotid artery stenoses. PC alone was measured in a further 84 patients with AAA and 16 with carotid artery stenoses. RESULTS: PC was below the normal range in 8/105 patients and mean PC (215x10(9)/l, S.D. 47.5) was significantly lower than that of a control population (242x10(9)/l, S.D. 16.8) and patients with carotid disease (269x10(9)/l, S.D. 57). Glycocalicin level was above the normal range in 7/23 patients and the median level (28 fg/plt) was significantly higher than that of a normal population (21.6 fg/plt) and patients with carotid disease (12.3 fg/plt). Fibrinogen levels, PTR and APPT were all within the normal range. One patient had a minimally elevated level of D-dimer. CONCLUSIONS: the combination of low PC and high glycocalicin levels suggests that there is increased platelet destruction, most likely due to activation within the aneurysm sac.

Aged↗

PubMedDate not supplied

Platelet count and platelet function in patients with angina pectoris (before and after a cycloergometric exercise test).

Platelet count and platelet function (circulating platelet aggregates, retention by glass beads and aggregation) were studied under basal conditions and after a cycloergometric exercise test in 10 subjects with stable angina pectoris and 10 normal subjects. There were no baseline differences between patients and controls in any of the tests of platelet function, nor did the values change after the exercise test. There was, however, a significant increase in the number of circulating platelets after the test in angina patients. Possible reasons for this phenomenon are discussed, with emphasis on the role of catecholamine hypersecretion induced by the physical exercise.

Adult↗

PubMed2006

Platelet count, mean platelet volume, platelet distribution width, and plateletcrit do not correlate with optical platelet aggregation responses in healthy volunteers.

BACKGROUND: Recent advances in technology have made it possible to record various platelet indices. There have been many reports about platelet indices and platelet disorders. The aim of this study is to investigate whether anatomical indices have a correlation with functional aggregation responses using optical method in healthy adults and to evaluate the predictive significance of platelet indices over platelet aggregation responses. METHODS: This study was carried on 31 adults whose ages ranging between 20 and 42. Platelet parameters, including platelet count, mean platelet volume, platelet distribution width and plateletcrit were determined in platelet rich plasma using Abbott Cell-Dyn 4.000. Platelet aggregation was induced by adenosine diphosphate, collagen and epinephrine. Optical aggregation was performed using a turbidometric method. RESULTS: We have observed no correlation between any of platelet indices measured and platelet aggregation responses. CONCLUSIONS: As a result, we found no correlation between platelet aggregation responses obtained with optical method and platelet indices proposed as indicators of certain pathologic conditions, and it does not seem possible to use platelet indices as a direct indicator of platelet activation. In conditions where platelet functions should have been assessed, platelet indices alone are inappropriate and further evaluation is necessary with different methods.

Adult↗

PubMed1979

Thrombocytopenic episodes in patients with well-functioning renal allografts. Inverse relationship between platelet count and platelet size pointing to intermittent platelet destruction.

20 out of 50 patients with well-funcioning renal allograft displayed at least one platelet count below 110 X 10(9)/1 (mean -2 SD of controls). For estimation of platelet production during thrombocytopenic episodes, the percentage of large platelets in the peripheral blood was determined which revealed an inverse relationship (p less than 0.01) to the platelet count, indicating that these thrombocytopenias were due to increased platelet consumption. Immunosuppressive treatment as well as rejection processes could be excluded as major pathogenetic factors whereas anti-platelet autoantibodies may contribute to this phenomenon.

Autoantibodies↗

PubMed1989

The effect of histamine challenge on platelet count and platelet activation.

There is conflicting evidence of platelet involvement in asthmatic bronchoconstriction. We sought direct evidence of platelet activation and indirect evidence of platelet sequestration following histamine challenge (HC) in 14 asthmatics and seven non asthmatic control subjects. Peripheral platelet counts and levels of beta thromboglobulin (BTG) were measured immediately before and following HC in the 21 subjects. There were no significant differences in the platelet counts or BTG levels, before or after HC, within or between the two groups. These results do not support platelet activation or accumulation in the lungs occurring immediately following histamine induced bronchoconstriction in asthmatics.

Adolescent↗

PubMed1979

Comparison of platelet count and platelet protein methods for determination of platelet MAO activity.

Platelet monoamine oxidase (MAO) activity in 10 normal volunteers was studied as a function of platelet protein or electronically-determined platelet counts. Comparisons of the two methods were made for samples assayed on the same day as well as one week later. The MAO activities resulting from both methods were significantly correlated and reproducible but the results of the platelet count method were, in most instances, slightly but significantly more reliable than the platelet protein method. The relevance of these results to the controversy concerning platelet MAO activity in schizophrenia is discussed.

Blood Cell Count↗

PubMed1981

Accuracy of low electronic platelet counts using platelet distribution curves.

At low platelet levels electronic counts are inaccurate because background counts are an increasingly important contribution to the total count. In this study the background contribution was selectively eliminated by coupling a multichannel particle size analyzer (Coulter Channelyzer II) to an electronic counter (Coulter ZBI). Platelet counts below 50 x 10(9)/l required an adjustment of the lower threshold in 11 of 15 specimens. Non-platelet counts averaged 18 percent of the platelet particle count with a maximum value of 50 percent. In contrast, platelet counts between 50 to 100 x 10(9)/l required only a minimum adjustment of the lower threshold and extraneous counts averaged only 2.7 percent of the platelet particle count. Phase platelet counts ranging from 4.0 x 10(9)/l to 115 x 10(9)/l were compared in ZBI-Channelyzer counts in 30 patients. The electronic counts showed good agreement with the reference method. Results were statistically analyzed using linear regression analysis and paired t tests. Technical errors involved in electronic and visual platelet counts are discussed.

Blood Platelets↗

PubMed1985

Sedimentation rate, leucocytes, platelet count and haemoglobin in bronchial carcinoma: an epidemiological study.

Erythrocyte sedimentation rate (ESR), leucocyte count, platelet count, haemoglobin concentration (Hb) and survival were studied in an epidemiological material of 258 patients with bronchial carcinoma. The mean ESR was elevated (48.1 mm/h) and, more so in squamous cell and small cell carcinoma than in large cell and adenocarcinoma. Leucocytosis, over 9 X 10(9)/l, was found in 39% of the patients and thrombocytosis, over 400 X 10(9)/l, in 13% of the patients. Nine per cent of the patients were anaemic, with Hb lower than 11 g/l. There was a statistically significant positive correlation between ESR, leucocyte count and platelet count, but a negative correlation was found between these 3 variables and Hb. ESR, leucocyte count and platelet count also correlated to survival at a statistically significant level. Multiple regression analysis of these laboratory variables showed that they explain about 8% of the great variations in survival time.

Adenocarcinoma↗

PubMed2006

Intravenous administration of choline or cdp-choline improves platelet count and platelet closure times in endotoxin-treated dogs.

This study was performed to assess the effects of intravenous choline chloride and cytidine-5'-diphosphate choline (CDP-choline) treatments on circulating platelet, white blood cell, and red blood cell counts and platelet functions in response to endotoxin. Saline (0.2 mL/kg), choline chloride (20 mg/kg), or CDP-choline (70 mg/kg) were given intravenously three times at 4-h intervals, and endotoxemia was induced by endotoxin (E. coli 055:B5, 20 microg/kg) infusion, 5 min after the first treatment. Blood samples were collected before and at multiple time points after the challenge, for a panel of hematologic parameters and platelet closure times measured by PFA-100. In saline-treated dogs, circulating platelet counts decreased by 85% (P < 0.001) at 0.5 h and remained low by 36%-80% (P < 0.5-0.001) 1-12 h after endotoxin. Circulating WBC counts decreased by 80%-90% (P < 0.001) at 0.5-2 h, and increased (P < 0.001) by 190% 12 h after the endotoxin. In response to endotoxin, RBCs increased by 10%-13% (P < 0.05) at 1-12 h. Endotoxin-induced decline in circulating platelets was attenuated at 0.5 h (P < 0.05-0.01) and reversed at 1-12 h (P < 0.05-0.001) by choline. Platelet closure times were shortened from 81 +/- 10 s and 135 +/- 10 s to 29 +/- 5 s (P < 0.001) and 60 +/- 3 s (P < 0.001) at 0.5 h, and prolonged (P < 0.001) at 1-8 h after endotoxin induction. Endotoxin-induced shortening in platelet closure times was attenuated (P < 0.05) and blocked (P < 0.01) by choline and CDP-choline, respectively. These results showed that choline and CDP-choline treatments improved circulating platelet counts and platelet function during endotoxemia in dogs.

Animals↗

PubMed2003

Reference intervals and age-related changes for platelet count, mean platelet volume and plateletcrit in healthy pre-weaning piglets in Italy.

Platelet count (PLT) mean platelet volume (MPV) and plateletcrit (PCT) were determined for 117 Landrace x Large White piglets aged 3-21 days; counts were performed with an automated blood cell counter (ABX Pentra 120). Reference values were estimated following the guidelines of the International Federation of Clinical Chemistry (IFCC) and the International Committee for Standardization in Haematology (ICSH). The calculated central 95% reference limits for PLT was 49.9-516.2 x 10(9)/1, for MPV 6.71-9.91 fl and for PCT 0.009-0.395%. When observations are divided into three age groups (about 1 week each) there is an increase in mean PLT count and PCT in 2-week piglets, and a decrease in MPV from the first to the third week of life. These reference values provide guidelines for interpreting for experimental and clinical observations, as well as for monitoring of the health status of similar aged piglets determined using automated impedance-light focusing methodology.

Age Factors↗

PubMed1998

Apheresis platelets: emerging issues related to donor platelet count, apheresis platelet yield, and platelet transfusion dose.

Emerging issues in stimulating apheresis platelet donors with platelet growth factors, the relative costs of apheresis and random donor platelet concentrates, optimal platelet transfusion dose, and leucoreduction of platelet products have caused renewed debate regarding apheresis products vs. random, pooled concentrates. The future role of apheresis products in platelet transfusion therapy will in large part be determined by costs, which are increasingly recognized to be influenced by donor platelet count, apheresis yield, and platelet transfusion dose.

Blood Donors↗

PubMed1990

Platelets in hyperthyroidism: studies on platelet counts, mean platelet volume, 111-indium-labeled platelet kinetics, and platelet-associated immunoglobulins G and M.

We compared in 15 patients with hyperthyroidism (11 with Graves' disease, 3 with toxic adenoma, and 1 with multinodular goiter) platelet counts (PC) and mean platelet volume (MPV) before and 3 weeks after initiation of antithyroid drug therapy when the patients were euthyroid. In addition, platelet kinetic studies of autologous 111-indium-labeled platelets and platelet-associated immunoglobulins G and M (PAIgG and PAIgM, respectively) were investigated. The control group for the platelet kinetic studies consisted of 2 patients with diffuse nontoxic goiter and 86 patients who were studied for evaluation of their arteriosclerotic vascular disease. After 3 weeks of antithyroid drug therapy there was a significant increase in PC and a decrease in MPV compared with the pretreatment values (pretreatment PC median, 215 X 10(9)/L; range, 96-350 X 10(9)/L; PC median 3 weeks later, 248 X 10(9)/L; range, 157-384 X 10(9)/L; P less than 0.005; pretreatment MPV median, 10.6 fL; range, 9.1-13.2 fL; MPV 3 weeks later, 9.9 fL; range, 8.4-11.0 fL; P less than 0.005). 111-Indium platelet recovery was normal in all subjects. Platelet lifespan was significantly shortened in the patients with hyperthyroidism compared with the control group (median, 163.8 h; range, 128.5-206 h; vs. 180.0 h; range, 138.3-231.5 h; P less than 0.05). Platelet turnover averaged 45.6 (range, 25.6-71.9) X 10(9)/L.day; values above the limit of normal were found in 7 of 15 patients with hyperthyroidism. Three patients with Graves' disease had elevated levels of PAIgG; 1 of these patients had elevated levels of PAIgM and was the only patient with thrombocytopenia (PC, 96 X 10(9)/L). Various combinations of statistical correlations between the degree of hyperthyroidism, pretreatment PC and MPV, platelet kinetic studies, levels of PAIg, and serum levels of antithyroid antibodies revealed no significant differences. These findings suggest that the platelet changes observed in hyperthyroidism, such as lower PC and increased MPV, together with the shortened platelet lifespan reflect metabolically rather than immunologically mediated phenomena, although these may be involved in cases with marked thrombocytopenia.

Adolescent↗

PubMed1992

An optical method for the determination of platelet count in platelet samples contaminated with red blood cells.

We present a simple photometric method to determine the total concentration of platelets present in a sample independently of red blood cell concentration. Standard optical density curves for platelet samples ranging in concentration from 0 to 1.5 x 10(9) cells/ml and contaminated with red blood cells ranging in concentration from 0 to 0.03 x 10(9) cells/ml are determined. A study of the absorbance spectra of red blood cells and platelets suggests that by calculating the absorbance difference between two wavelengths, an estimate of red blood cell concentration can be made. Then, in the second step of this two-step method, the individual absorbance measurements at the two wavelengths are matched to the standard values determined previously to derive an estimate of platelet concentration. In a trial of 62 unknown platelet samples contaminated with red blood cells, the standard deviation for the error in platelet count was 0.16 x 10(9) cells/ml with a mean difference of 0.011 x 10(9) platelets/ml. We conclude that our method may be useful in laboratories not equipped with electronic cell counters as well as in applications such as the development of noninvasive measurements of platelet concentration in platelet transfusion packs.

Erythrocytes↗

PubMed1980

A side-by-side evaluation of four platelet-counting instruments.

The performances of four instruments for counting platelets were evaluated in a side-by-side study: the Haema-Count MK-4/HC, an electronic impedance instrument that counts platelets in platelet-rich plasma; the Ultra-Flo 100, and the Coulter Counter Model S-Plus, electronic impedance instruments that count platelets in the presence of intact erythrocytes; and the AutoCounter, an optical instrument that counts platelets in the presence of lysed erythrocytes. The Ultra-Flo 100 and the S-Plus showed the best within-run precision, and all four instruments were considerably more precise than manual platelet counting, especially at low levels of platelet count. The four instruments were all linear in the ranges tested (5 to 650 x 10(9)/or greater), and sample carry-over was less than 0.7% for each. A noteworthy finding was that the erythrocyte concentration of the blood samples affected the displayed platelet count of the S-Plus and, to a lesser extent, that of the AutoCounter, in a predictable way, whereas it did not greatly affect the displayed count of the Ultra-Flo 100. In addition to differences in quality of performances, the four instruments differed considerably in speed and ease of operation and in cost.

Calibration↗