The possible value of platelet aggregation studies in patients with increased platelet number

Abstract

ADP, adrenalin and collagen platelet aggregation studies were performed in 54 patients with elevated platelet counts: 38 patients showed primary thrombocythemia and 16 secondary thrombocytosis. Patients with primary thrombocythemia (78.7%) showed a decrease aggregation pattern while in patients with secondary thrombocytosis platelet aggregation response was entirely normal. An increase in platelet aggregation was obtained in four patients with primary thrombocythemia. The platelet aggregation response did not appear to be related to circulating platelet number. A relationship between increased platelet aggregation and the occurrence of thrombosis was demonstrated. Similarly, a correction between impaired platelet aggregation and bleeding was also present. These results emphasize the diagnostic value of platelet aggregation studies in patients with elevated platelet number.

Clinical Significance of Beta-Thromboglobulin in Patients with High Platelet Count

“…These patients, therefore, surely show the pattern of an in vivo platelet activation [11]. The higher in cidence of thrombotic complications (66%) found in patients with MPD and in creased fkg ratio also supports the correla tion between platelet function and clinical events as previously demonstrated by platelet aggregation studies [10], It is also interesting that 1 of the 2 patients with ST and high fkg ratio had thrombotic mani festations.…”

“…In 53 patients M PD was considered, whereas in the other 21 the increased platelet counts were re corded as ST. Clinical and laboratory findings show clear differences between the two groups of patients [10,12,21]. Pa tients with ST are almost asymptomatic and show a normal platelet aggregation pattern in 95% of the cases.…”

“…Platelet count was performed in blood and in platelet-rich plasma (PRP) using a platelet counter HPC 32 Hycel (Amplimedical, Milan, Italy). Platelet aggregation was con sidered abnormal according to quantitative criteria already dealt with [10], maintaining the values as de creased or increased only when they appeared abnor mal with 2 out of 3 indicators used (ADP 2 j/mol/1, adrenalin 10 um ol/l, collagen 2 /tg/ml). The platelet aggregation was expressed as maximal variation in optical density between PRP and platelet-poor plas ma in comparison with the average ± 2 SD of 57 con trol subjects (ADP 56±28% irreversible wave, adrenalin 60 ±22% with second wave, collagen 70 ±36%).…”

“…On this subject many investigations demonstrate some correlation between platelet aggregation and thrombotic or hemorrhagic complications [10] in pa tients with increased platelet counts, but the use of platelet aggregation as a sure prognostic test is certainly still untenable.…”

Acquired Type I von Willebrand’s Disease in a Patient with Essential Thrombocytosis

“…Both thrombotic and haemorrhagic complications may occur in patients with myeloproliferative disease (MPD) [3,4,8], often as an expression of different steps of the same condition. Furthermore, no strict correlation between clinical manifestations and in creased platelet number 'per se' is seen, suggesting the presence of qualitative platelet defects in addition to the simple enhancement of platelet count.…”