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PubMed1998

Variables associated with the platelet count 6 weeks after autologous peripheral blood progenitor cell transplantation.

While abundant data exist documenting variables associated with early platelet engraftment after autologous PBPC transplantation, data concerning later sustained platelet engraftment is sparse. We retrospectively examined a series of 80 patients undergoing autologous PBPC transplantation with respect to their platelet count 6 weeks after transplant. Underlying diagnoses included breast cancer (n = 33), non-Hodgkin's lymphoma (n = 32), Hodgkin's disease (n = 9), and other hematologic malignancies (n = 6). Patients received G-CSF for PBPC mobilization and collected a target threshold number of 2.0 x 10(6) CD34+ cells per kilogram. A univariate analysis revealed that a diagnosis of breast cancer, fewer courses of prior chemotherapy, younger age and complete remission were associated with a higher 6-week platelet count. Additionally, the ability to collect the threshold number of CD34+ with fewer sessions of leukapheresis was also associated with a higher 6-week platelet count. The platelet count and the white blood cell count at the initiation of PBPC collection was also associated with a higher 6-week platelet count. A multivariate analysis revealed a higher platelet count on the first day of pheresis, fewer phereses required to collect 2 x 10(6) CD34+ cells per kilogram, and a diagnosis of breast cancer were all associated with a higher 6-week post-transplant platelet count. Seven patients failed to reach a 6-week platelet count of 30 x 10(9)/l and an additional five patients had a platelet count of 30-50 x 10(9)/l. We conclude that underlying clinical characteristics, as well as hematologic variables at the time of PBPC collection, influence later, sustained platelet engraftment. A percentage of patients have poor sustained platelet engraftment and may be candidates for new cytokines that specifically target megakaryocyte growth and development.

Adult↗

PubMed1995

Effect of intravenous gammaglobulin (IVIG) on the platelet count in patients with Wiskott-Aldrich syndrome.

The ability of IVIG to increase platelet counts in patients with idiopathic thrombocytopenic purpura suggests its potential usefulness in other disease states characterized by low platelet counts. This possibility was evaluated in nine patients with the Wiskott-Aldrich syndrome (WAS) who received IVIG, at a dose of 400 mg/kg every 4 weeks. The mean platelet count prior to institution of IVIG was 32,000/cumm (range 2,400 to 98,000). Following administration of IVIG, the platelet count ranged between 5,000 and 85,000/cumm. There were no immediate increases in platelet counts after IVIG infusion in any patient who had serial platelet counts. During treatment, patients were not given any routine platelet transfusions for low platelet counts. However, while on IVIG, two patients showed a good response to platelet transfusion prior to surgical procedures. In conclusion, chronic IVIG therapy does not appear to affect platelet counts in patients with the Wiskott-Aldrich syndrome.

Child↗

PubMed1995

Reliability of automated platelet counts: comparison with manual method and utility for prediction of clinical bleeding.

The 20 x 10(9)/L (20,000/microliters) threshold for prophylactic platelet transfusion may be unnecessarily high. The widespread use of this threshold may reflect lack of confidence in the reliability of low platelet counts. We evaluated the performance of automated platelet counts and their relation to clinical bleeding. First, we prepared serial blood dilutions with "target" platelet counts from 2 to 40 x 10(9)/L. For the 48 measurements on 2 x 10(9)/L "target" dilutions, values of 1 or 2 x 10(9)/L were obtained with the Sysmex NE-8000 analyzer (mean 1.44 x 10(9)/L; SD 0.31 x 10(9)/L). Similarly, for 5 x 10(9)/L "target" counts, automated counts were 3-6 x 10(9)/L (mean 4.42 x 10(9)/L; SD 0.18 x 10(9)/L). Similar results were observed with all other "target" levels, with coefficients of variation (CV) from 6.39% to 7.71% with 10-40 x 10(9)/L "target" values. Secondly, we compared triplicate automated and manual platelet counts on thrombocytopenic patients with platelet counts from 4-30 x 10(9)/L. The triplicate automated platelet counts differed by no more than 5 x 10(9)/L among themselves, whereas the manual counts varied by as much as 30 x 10(9)/L. Mean platelet counts: automated, 14.40 x 10(9)/L (CV 10.12%); manual, 16.48 x 10(9)/L (CV 30.39%) (P = 0.038 for counts; P < 0.001 for CV). Finally, we prospectively evaluated bleeding in thrombocytopenic patients (1,809 patient-days of observation). Univariate and multivariate logistic regression analysis revealed highly significant correlations between the automated platelet count and major and minor bleeding manifestations. Thus, automated platelet counts are highly reliable and accurately predict clinical bleeding. The use of automated analyzers should facilitate improved prophylactic platelet transfusion protocols.

Automation↗

PubMed2003

Transient elevation of platelet count in patients with chronic idiopathic thrombocytopenic purpura: association with infection.

Platelet count occasionally increases after infection in patients with chronic idiopathic thrombocytopenic purpura (ITP). We report 5 such patients. Three of them were males. Between November 1992 and December 2001, increased platelet counts were observed 9 times in 5 patients with chronic ITP. Corticosteroids were administered during 7 episodes; splenectomy was performed to treat 3 episodes. Antibiotics were administered in the course of 6 episodes to treat complicating infection. Platelet counts showing 1.4- to 24-fold increases have been observed. Median duration from the onset of infection until peak platelet count was 14 days. However, platelet count finally decreased to the initial level in all episodes. These findings suggest that infection is associated with the elevation of platelet count in some patients with chronic ITP, although this phenomenon is transient.

Adrenal Cortex Hormones↗

PubMed1987

Reduction of platelet counts induced by mechanical ventilation in newborn infants.

The association between platelet counts and mechanical ventilation was assessed in 61 newborn infants with respiratory distress syndrome, 10 infants with congenital diaphragmatic hernia, and 10 infants with tracheoesophageal fistula. A significant decrease in platelet counts was observed during mechanical ventilation: (mean +/- SD) reduction of 39% +/- 5%, 42% +/- 5.6%, and 11.9% +/- 5.4% in the three groups, respectively, independent of other causes. In the group with congenital diaphragmatic hernia, there was a significant correlation between mean airway pressure and the reduction in platelet counts. In a subsequent series of experiments, platelet counts were recorded before and during ventilation in rabbits. A significant mean decrease of 37.3% in platelet counts was associated with ventilation with either air or pure oxygen. Results of these studies indicate that mechanical ventilation itself may cause a major decrease in platelet count in newborn infants.

Animals↗

PubMed2005

White blood cell and platelet counts can be used to differentiate between infection and the normal response after splenectomy for trauma: prospective validation.

BACKGROUND: Transient elevations of the serum white blood cell count (WBC) and platelet count (PC) are normal physiologic responses after splenectomy. The clinician is often challenged to identify an infection in a postsplenectomy patient with an elevated WBC. A previous retrospective study found that a WBC greater than 15 x 10/microL and a PC/WBC ratio < 20 on postoperative day 5, in addition to an Injury Severity Score > 16, were highly associated with infection and should not be considered as part of the physiologic response to splenectomy. The current study intends to prospectively validate the WBC and PC/WBC ratio on postoperative day 5 as markers of infection after splenectomy for trauma. METHODS: Consecutive trauma patients admitted to an urban, Level I trauma center who underwent splenectomy from June 2002 to December 2004 were collected prospectively. In addition to admission demographics, variables collected included daily WBC, PC, and PC/WBC ratio during the first 10 postoperative days. Outcome was the presence of infection. Patients with infection (infected group) were compared with those without infection (noninfected group). Injury Severity Score > 16, postoperative day 5 WBC > 15 x 10/microL, and PC/WBC ratio < 20 were investigated as risk factors for postsplenectomy infection. RESULTS: There were 96 trauma patients who underwent splenectomy during the study period, and 44 (46%) developed a postoperative infection. Infectious complications included pneumonia (n = 30 [31%]), followed by septicemia (n = 20 [21%]), urinary tract infection (n = 12 [13), abdominal abscess (n = 9 [9%]), and wound infection (n = 4 [4%]). Postoperative day 5 was the first day that infected patients had a higher WBC (16 +/- 6 x 10/microL vs. 14 +/- 4 x 10/microL, p = 0.03) and a lower PC/WBC ratio (15 +/- 9 vs. 24 +/- 12, p = 0.002) than noninfected patients. The presence of two or more risk factors for infection was associated with a 79% rate of infection, and no patient developed an infection if all three risk factors were absent. CONCLUSION: On postoperative day 5 after splenectomy for trauma, a WBC greater than 15 x 10/microL and a PC/WBC ratio less than 20 are reliable markers of infection.

Adult↗

PubMed2002

Time course of platelet counts in critically ill patients.

BACKGROUND: Although thrombocytopenia in the intensive care unit (ICU) is associated with a poorer outcome, the precise relationship between the time course of platelet counts and the mortality rate has not been well defined. OBJECTIVE: To describe the time course of the platelet count in relation to the mortality rate in critically ill patients. DESIGN: Substudy of a prospective, multicenter, observational cohort analysis. SETTING: Forty ICUs in 16 countries from Europe, America, and Australia. PATIENTS: Data were collected from all ICU admissions in a 1-month period, excluding patients younger than 12 yrs old and those who stayed in the ICU for <48 hrs after uncomplicated surgery. A total of 1,449 critically ill patients were enrolled, including 257 who stayed in the ICU for >2 wks. INTERVENTIONS: None. MEASUREMENTS: Platelet counts were collected daily throughout the ICU stay, together with other measures of organ dysfunction. Thrombocytopenia was defined as a platelet count of <150 x 103/mm3. A relative increase in platelet count was defined as a 25% increase above the admission value, together with an absolute platelet count of > or =150 x 103/mm3. MAIN RESULTS: For the entire population, the platelet count was lower in the 313 nonsurvivors than in the 1,131 survivors throughout the ICU course. Of the 257 patients who stayed in the ICU for >2 wks, 187 (64%) survived. The platelet count decreased significantly in the first days after admission to reach a nadir on day 4 in both survivors and nonsurvivors. In the survivors, the platelet count returned to the admission value by the end of the first week and continued to rise to become significantly greater than the admission value by day 9. In the nonsurvivors, the platelet count also returned to the admission value after 1 wk, but there was no subsequent increase in platelet count. A total of 138 (54%) patients had thrombocytopenia on day 4, and these patients had a greater mortality rate than the other patients (33% vs. 16%; p <.05). On day 14, 51 (20%) patients had thrombocytopenia, and these patients had a greater mortality rate than the other patients (66% vs. 16%; p <.05). Thrombocytopenia was less common on day 14 than on day 4 (20% vs. 54%; p <.05), but the mortality rate was greater in the thrombocytopenic patients on day 14 than those who were thrombocytopenic on day 4 (66% vs. 33%; p <.05). The ICU mortality rate of nonthrombocytopenic patients on day 14 was also significantly lower in patients with, than without, a relative increase in platelet count on day 14 (11% vs. 30%; p <.05). CONCLUSION: Platelet count changes in the critically ill have a biphasic pattern that is different in survivors and nonsurvivors. Late thrombocytopenia is more predictive of death than early thrombocytopenia. A relative increase in platelet count after thrombocytopenia was present in survivors but not in nonsurvivors. Although a single measured platelet count is of little value for predicting outcome, changes in platelet count over time are related to patient outcome.

Adolescent↗

PubMed1992

Gender differences in platelet count and its association with cigarette smoking in a large cohort in Israel.

Cigarette smoking has an effect on platelet function and aggregation although the sensitivity of platelet count in reflecting this phenomenon is not known. The association of platelet count with smoking habits was examined in a cohort of 5017 Israeli industrial workers aged 20-64 years. Males had a significantly lower age-adjusted mean platelet count than females (225,600 vs 247,800/microliters; p less than 0.001). Female smokers had lower platelet counts than non-smokers (231,000 for heavy vs 252,000 for never smokers) with a strong dose-response relationship (p less than 0.0001), whereas among males platelet count was slightly higher in smokers (224,000 for non-smokers vs 227,000 for heavy smokers; p = 0.243). The difference in platelet count between the sexes remained almost identical after controlling for smoking status and hematocrit. In multiple regression analysis, the negative association between smoking and platelet count in women remained highly significant (p less than 0.001) after controlling for ethnic origin, alcohol consumption, body mass, hematocrit, cholesterol and HDL-cholesterol, whereas for males the slight positive association was not significant. The reduced platelet count observed in males compared with females and in female smokers, suggests that platelet count may reflect sex differences in hemostasis and the effects of smoking on the hemostatic system. This may have implications for the mechanisms underlying the pathogenesis of ischemic heart disease and should be explored further.

Adult↗

PubMed2000

A novel approach to the assessment of variations in the human platelet count.

This is the first report of a method to assess the significance of numerical changes in the platelet count based upon a result exceeding the normal intra-individual variation in platelet numbers. Serial platelet counts from 3,789 subjects were analysed to determine the intra-individual variation in platelet numbers. A platelet count difference of 98 x 10(9)/L in males was found to represent a change that would occur by chance in less than 1 in 1,000 platelet count determinations. Tables to determine the significance of platelet number variations, given N previous observations, are provided at two probability levels. The repeatability of the platelet count was calculated as 0.871 (males) and 0.849 (females) indicating that the heritability of platelet count is high and that the platelet count is predominantly genetically determined. A seasonal variation in platelet count was found with a 'winter' versus 'summer' difference of 5.10 X 10(9)/L (males) and 5.82 x 10(9)/L (females).

Analysis of Variance↗

PubMed2005

[Analysis of 34 cases of systemic lupus erythematosus with decreased platelet count].

OBJECTIVE: To explore the clinical and laboratory examination features of systemic lupus erythematosus (SLE) with decreased platelet count. METHODS: Thirty-four SLE patients with decreased platelet count were analyzed for their initial symptoms, clinical manifestations, involvement of the organs and laboratory findings in comparison with 40 randomly selected SLE patients with normal platelet count. RESULTS: The SLE patients with decreased platelet count were more likely to develop kidney involvement than those with normal platelet, but the incidence of butterfly erythema was significantly lower in the former patients (PP<0.05). Some indices of laboratory examinations, such as CH(50), white blood cell reduction, rate of urine protein, thrombocytocrit and platelet distribution width were significantly higher in SLE patients with decreased platelet count than those with normal platelet count. CONCLUSIONS: The clinical manifestations and laboratory findings in SLE patients with decreased platelet count may differ from those of SLE patients with normal platelet.

Adolescent↗

PubMed2000

[Comparison of reticulated platelet count with plasma glycocalicin concentration as a marker of platelet turnover in patients with thrombocytopenic disorders].

Measurements of plasma glycocalicin (GC) and reticulated platelets (RP) have been reported to be useful for classifying thrombocytopenic disorders. However, there have been no reports comparing the clinical usefulness of the two methods. We measured GC and RP levels simultaneously in 39 patients with idiopathic thrombocytopenic purpura (ITP), 15 patients with aplastic anemia (AA), and 17 patients with hypoplastic thrombocytopenia (HypoT) due to chemotherapy. The GC index (GC level normalized for the individual platelet count) and the percentage of RP (%RP), a parameter of platelet life span, were very high (7.5 +/- 11.4 and 20.8 +/- 13.0%, respectively) in patients with ITP as compared with those of healthy subjects (1.3 +/- 0.5 and 7.9 +/- 2.5%, respectively). However, 6 AA patients and 14 HypoT patients, in whom platelet life span is thought to be normal, also had an elevated GC index, suggestive of a false positive result. The RP, a parameter of platelet production, was low in all AA and HypoT patients except for one in each case. However, the GC level, an additional parameter of platelet production, was normal in 4 AA and 8 HypoT patients, indicating that it is not a sensitive indicator. We conclude that the RP and %RP are more feasible markers of thrombopoiesis and platelet life span, respectively, than the GC level and GC index.

Blood Platelets↗

PubMedDate not supplied

Platelet counts in healthy adult Sierra Leoneans.

The platelet counts of 100 healthy Sierra Leoneans were determined. Fifty six (56) Males and Forty four (44) Females were included in the study. The mean platelet count was 197 x 10(9)/L(SD = 25 x 10(9)/L Range = 115-335 x 10(9)/L The results of this study compare favourably with those obtained from previous studies in other African Countries and confirms that the normal platelet count in the African is lower than in Caucasians.

Adult↗

PubMed1996

The reduction of large von Willebrand factor multimers in plasma in essential thrombocythaemia is related to the platelet count.

We have investigated the relationship between platelet count and large VWF (von Willebrand factor) multimers in the plasma of 36 patients with essential thrombocythaemia (ET) and 26 patients with reactive thrombocytosis (RT). In both ET and RT patients an inverse relationship could be established between platelet count and large VWF multimers in plasma as well in relatively decreased ristocetin cofactor/von Willebrand factor antigen and collagen binding activity/von Willebrand factor antigen ratios. A normalization of the platelet count was accompanied by restoration of a normal plasma VWF multimeric distribution. Our data suggest that increasing numbers of platelets circulating in blood result in increased removal of large VWF multimers from plasma.

Adult↗

PubMed1993

Plasma fibrinogen and platelet count in stroke.

Plasma fibrinogen levels and platelet counts were evaluated in 30 patients with acute ischemic cerebral infarction (CI) three and nine days after the onset of symptoms. Hyperfibrinogenemia (379.4 +/- 80.3 vs 327.3 +/- 48.3 mg/dL of controls, p < 0.005), a reduction of platelet count (207.133 +/- 48.388 vs 288.375 +/- 61.373 x 10(9)/L of controls, p < 0.001), and an inverse correlation (r = -0.41, p < 0.05) between the two parameters were observed on day three. On day nine, platelet counts normalized while plasma fibrinogen levels slightly increased; the inverse correlation no longer occurred. The results suggest that in the earliest phase of stroke plasma fibrinogen levels may condition the extent of platelet accumulation or consumption in the ischemic area. This confirms in vivo that the platelet aggregation process is strictly dependent on fibrinogen concentration.

Aged↗

PubMed1975

Platelet counts during normal pregnancy.

Eleven reports of platelet counts were found in the literature which reported a progressive increase, no change, or a progressive fall during pregnancy. The counts had been made using venous or capillary blood, with either simple dilution or red cell lysis prior to enumeration in a haemocytometer, with or without phase-contrast microscopy. It was therefore decided to examine whole blood platelet counts taken during normal pregnancy. Results from 405 venous blood samples, using an electronic platelet counter, confirmed the finding of a significant progressive fall in platelet counts during normal pregnancy, the lowest counts falling in some women outside the recognized normal range of values.

Blood Cell Count↗

PubMed2005

Accuracy of platelet counting haematology analysers in severe thrombocytopenia and potential impact on platelet transfusion.

Although haematology analysers provide reliable full blood counts, they are known to be inaccurate at enumerating platelets in severe thrombocytopenia. If the thresholds for platelet transfusion, currently set at 10 x 10(9)/l, are to be further reduced, it is vital that the limitations of current analysers are fully understood. The aim of this large multicentre study was to determine the accuracy of haematology analysers in current routine practice for platelet counts below 20 x 10(9)/l. Platelet counts estimated by analysers using optical, impedance and immunological methods were compared with the International Reference Method for platelet counting. The results demonstrated variation in platelet counting between different analysers and even the same type of analyser at different sites. Optical methods for platelet counting on the XE 2100, Advia 120, Cell-Dyn 4000 and H3* were not superior to impedance methods on the XE 2100, LH750 and Pentra analysers. All analysers except one overestimated the platelet count, which would result in under transfusion of platelets. This study highlights the inaccuracies of haematology analysers in platelet counting in severe thrombocytopenia. It re-emphasizes the need for external quality control to improve analyser calibration for samples with low platelet counts, and suggests that the optimal thresholds for prophylactic platelet transfusions should be re-evaluated.

Humans↗

PubMed2006

Platelet activation in Helicobacter pylori-associated idiopathic thrombocytopenic purpura: eradication reduces platelet activation but seldom improves platelet counts.

INTRODUCTION: It has been suggested that Helicobacter pylori eradication often increases platelet counts in patients with chronic idiopathic thrombocytopenic purpura (ITP). In addition, H. pylori has been shown to induce platelet activation (CD62p or P-selectin expression) in previous studies. We assessed the response of platelet count and CD62p expression after eradication therapy in patients with ITP and H. pylori infection. METHODS AND RESULTS: We prospectively studied 15 ITP patients diagnosed with H. pylori infection by serology and breath test. A follow-up breath test was used to document eradication. Two out of 15 patients showed improvement in platelet counts after 6 months, 1 of which may have had drug-induced thrombocytopenia. Overall, certain platelet response rate in our series was 6.7% (1/15). We found that platelet CD62p expression by flow cytometry was elevated in 10/15 (66.7%) H. pylori-infected patients, which is a statistically significant difference when compared with 3/33 (9.1%) control ITP patients seronegative for H. pylori (p = 0.002). In addition, eradication therapy decreased CD62p expression (p = 0.04). However, reduction in platelet activation was not associated with an increase in platelet counts (mean 72.4 x 10(9)/l before and 68.7 after therapy; p = 0.4). CONCLUSION: In our series, platelet activation was common in ITP patients with H. pylori, and eradication therapy decreased platelet activation but seldom increased platelet counts. Increased platelet CD62p expression is a putative link between chronic infections and atherosclerosis, but further study is needed to clarify the implications of our observation.

Adult↗

PubMed2002

Platelet counting by the coulter LH 750, sysmex XE 2100, and advia 120: a comparative analysis using the RBC/platelet ratio reference method.

We compared the accuracy and precision of the impedance platelet counts generated by the Beckman Coulter LH 750 and the Sysmex XE 2100 and the optical platelet counts produced by the Advia 120 and the Sysmex XE 2100 withflow cytometric reference platelet counts. Samples analyzed had platelet counts less than 150 x 10(3)/microL (150 x 10(9)/L) with a platelet flag or less than 75 x 10(3)/microL (75 x 10(9)/L) on the Sysmex SE 9500. The 105 samples were run sequentially through each analyzer. Anti-CD41 and anti-CD61 monoclonal antibodies were used for flow cytometric determination of the reference platelet count by the RBC/platelet ratio method. The Beckman Coulter and the Sysmex impedance platelet counts showed better correlation with the reference method than the optical platelet counts by the Advia and the Sysmex. At platelet transfusion thresholds of 10 and 20 x 10(3)/microL (10 and 20 x 10(9)/L), the precision of the impedance methods was somewhat better than that of the optical methods. Current methods of optical platelet counting may not be superior to impedance platelet counts for all patient populations.

Antibodies, Monoclonal↗