Whole Blood Platelet Count Research Articles

Arachidonic-acid-induced platelet aggregation is increased in male but not in female smokers

Arachidonic-acid-induced platelet aggregation was studied in 40 healthy drug-free subjects aged 18–43 years. Aggregation was elicited by lower concentrations of arachidonic acid in smoking men (n=10) than in non-smoking men (n=10)(p<0.05). No significant difference was found between smoking and non-smoking females. Adenosine-diphosphate-induced platelet aggregation was not increased in smokers. There was no difference between smokers and non-smokers with respect to mean platelet volume and count within each sex. Females and males differed regarding platelet count in whole blood and platelet sensitivity to arachidonic acid; both differences were secondary to the difference in hematocrit. The parallelism between an increased tendency to aggregation after arachidonic acid stimulation and an increased rate of myocardial infarction in male smokers, and the absence of both these phenomena in female smokers, might be of pathophysiological significance.

The effects of citalopram (Lu 10-171) on the serotonin (5-HT) uptake kinetics in platelets from endogenously depressed patients.

The uptake kinetics of serotonin (5-HT) in platelets from eight patients with endogenous depression was determined in platelet rich plasma (PRP). From the uptake data the Scatchard correlation coefficient (r[S] ), Sips' index of heterogeneity (alpha), Km and Vmax (Lineweaver-Burk) were calculated. The measurements were performed before and after two weeks treatment with Citalopram, 1-(3-dimethylaminopropyl)-1-(p-fluorophenyl)-5-phtalan carbonitrile (Lu 10-171), a selective 5-HT uptake inhibitor. After two weeks treatment with Citalopram (5, 25 or 50 mg/day) a lowered platelet count in whole blood and PRP was observed and none of the patients had a measurable 5-HT uptake for which kinetic parameters (Km and Vmax, Lineweaver-Burk) could be calculated. However, all the patients but one improved significantly in Global score.

Effect on the uptake kinetics of serotonin (5-hydroxytryptamine) in platelets from workers with long-term exposure to organic solvents. A pilot study.

Six workers from a paint industry were examined concerning the concentration of solvents in the breathing zone, the platelet count and kinetic uptake of serotonin [5-hydroxytryptamine (5-HT)], the serum concentration of calcium, potassium and sodium, and pH. The degree of exposure was found to be moderate. The results showed a decrease in platelet count in whole blood and platelet-rich plasma. The maximum uptake rate for serotonin in platelets (Vmax) was significantly increased compared to that of nonexposed subjects. No changes in the ionic concentration and pH of serum were observed. One worker was reexamined after a six-week period of nonexposure. Though the measured platelet variables were still aberrant, the values approached normal.

The effect of radiographic contrast agents on bleeding time and platelet aggregation.

The purpose of this study was to determine whether the use of relatively small amounts of radiographic contrast agents may impair hemostasis. Before and after injection of contrast agents, we measured the template bleeding time, platelet count in whole blood and platelet-rich plasma, platelet aggregation induced by epinephrine and adenosine diphosphate (ADP), and percent disaggregation of ADP-induced platelet aggregates in platelet-rich plasma of 18 patients. Ten patients received 50-100 ml of sodium iothalamate (66.8%) for intravenous urography and 8 patients received 125-200 ml of a combination of meglumine diatrizoate (66%) and sodium diatrizoate (10%) for coronary angiography and left ventriculography. Neither group demonstrated a statistically significant mean difference (p greater than 0.05) for any parameter measured before and after administration of the contrast agents. However, 2 patients who received diatrizoate had lengthening of their bleeding times to greater than twice the baseline value without any change in in vitro platelet aggregation. Physicians should be aware of this potential cause of bleeding which could be of particular danger to patients undergoing cardiopulmonary bypass with its inherent hemostatic defects.

Increased uptake of serotonin in platelets from car painters occupationally exposed to mixtures of solvents and organic isocyanates.

Twelve car painters occupationally exposed to mixtures of solvents and organic isocyanates were investigated concerning serotonin uptake in platelets. The data from the exposed workers were compared to data from a reference group consisting of 50 nonexposed volunteers. The mean platelet count in whole blood of the exposed workers was markedly lower than the corresponding value of the reference group. Three workers had values below the lower limit of the 95% tolerance interval of the referents. In both groups the serotonin transport strictly obeyed Michaelis-Menten's simple saturation kinetics. Nine of the twelve exposed workers had uptake rates which were significantly higher (p = 0.05) than those of the referents. The obtained data suggest that the present method may be used to reveal early organ damage, prior to the appearance of clinical symptoms, due to intermittent exposure to organic solvents and isocyanates.

Evaluation of automated whole-blood platelet counts and particle sizing.

The Coulter Counter model S-Plus measures the erythrocyte, leukocyte, and platelet counts, and the mean cell volume of erythrocytes and platelets. Two additional features are novel to the instrument: erythrocyte distribution width (RDW), an index of erythrocyte volume heterogeneity, and mean platelet volume. For 677 subjects, we compared these measurements with complete blood counts obtained by a standard instrument, platelet counts from platelet-rich plasma (PRP), and histograms of erythrocyte and platelet volumes generated by free-standing equipment. The two methods correlated well (r = 0.97) for the complete blood count and the mean platelet volume. The whole-blood platelet count correlated well (r = 0.97) with the PRP platelet count, with whole-blood counts on average 5% higher than PRP counts. The whole-blood index of erythrocyte volume heterogeneity, RDW, correlated less well (r = 0.81) with the erythrocyte coefficient of variation measured by histogram. RDW was abnormal for three of 100 normal subjects with normal histograms. RDW was less sensitive (78% vs. 97%) and less specific (94% vs. 97%) than erythrocyte histograms in distinguishing iron deficiency from heterozygous alpha- or beta-thalassemia. We conclude that the Coulter Counter Model S-Plus reliably measures complete blood cell count, platelet count, and mean cell volumes, but analyzes erythrocyte volume distribution less well than does a histogram.

Platelet counting in whole blood by means of a new counter with hydrodynamic focused aperture (author's transl)

Platelet counts in whole blood were performed by means of a new particle analyzer with a hydrodynamic focused aperture (Ultra-Flo 100) and its values were compared with the results obtained by an optical counting chamber. The comparison yielded good agreement of the values within the evaluated range of 3-963 G/l thrombocytes. Especially remarkable is the good correlation of the markedly thrombocytopenic values. Equally reliable is the counting of thrombocytes in blood with markedly elevated erythrocytes. The simple procedure of sample preparing combined with the stand-by technic of the analyzer provides advantageous conditions for using it likewisely in routine and emergency laboratories.

Platelet estimation in whole blood

An application of particle size analysis is described for the estimation of platelet counts in whole blood based on a variable size threshold and baseline. The simplicity of the sample preparation for this technique may enable its automation as a semiquantitative screening method. Platelets, defined as particles to the platelet side and above the minimum point between the platelet and red cell distributions were counted on specially designed electronics. The system divides the normal size distribution from the smallest platelet to the smallest red cell into four equal windows and performs three integrations to calculate the best result.