ristocetin and Myelodysplastic-Syndromes

Hemorrhagic tendency in patients with myelodysplastic syndrome (MDS) is mainly attributed to thrombocytopenia. However, platelet function in these patients has not been thoroughly investigated.. The aim of our study is to evaluate platelet function in patients with primary MDS.. Platelet function was studied with aggregometry in response to ristocetin, collagen, ADP and adrenaline in 26 MDS patients and 15 healthy individuals.. Aggregation was defective in 21 patients (80.7%). Adrenaline was the agonist with the most profound defect (45.9%), followed by ADP (58.7%), whereas aggregation with ristocetin and collagen was at the borderline. Abnormal aggregation to all four agonists was detected in 6 patients (23%). On the contrary, aggregation results were normal in only 5 patients (19.2%). RAEB-t (refractory anemia with excess blasts in transformation) patients were most seriously affected.. MDS patients have impaired platelet aggregation in response to one or more stimulants. Platelet aggregation was not statistically different between MDS patients at early stages of the disease (<12 months) and those at later stages (>12 months). Defective platelet aggregation is strongly related to MDS of worse prognosis. None of our patients was detected to have hyperfunctional platelets, defined as platelets aggregating spontaneously. Functional defects in MDS do not elicit hemorrhagic tendency.

Topics: Adenosine Diphosphate; Aged; Aged, 80 and over; Collagen; Epinephrine; Female; Hemorrhagic Disorders; Humans; Male; Middle Aged; Myelodysplastic Syndromes; Platelet Aggregation; Ristocetin; Time Factors

The current study was aimed at investigating platelet function in MDS and its clinical significance. There were 23 patients with untreated MDS at presentation, including refractory anemia (RA), RA with ringed sideroblasts, RA and excess blasts and chronic myelomonocytic leukemia RAEBt. The mean platelet count was 167.9 x 109/L. Patients with a platelet count less than 70 x 109/l were excluded. The mean bleeding time (BT) was 2.7 min. Only four MDS patients had BT longer than the normal 1-4 min range. Platelet aggregation (PA) was studied with epinephrine (Epi), ADP, arachidonic acid (AA), ristocetin and collagen. Overall, 16 (70%) patients had PA abnormality, 65% had impaired Epi-induced PA, 57% demonstrated reduced ADP-induced PA. AA, ristocetin and collagen was decreased PA in 48, 22 and 17%, respectively. Five patients (22%) demonstrated spontaneous PA. Only seven patients (30%) were found to have normal PA with all five inducers. Six (26%) patients had spontaneous mild bleeding and all six bleeding MDS patients demonstrated at least one abnormal platelet function. The only bleeding patient with all five PA tests normal demonstrated prolonged BT. In the present study of 23 newly diagnosed MDS patients, PA abnormalities were relatively common, the BTs were usually normal, and bleedings were relatively uncommon and mild at platelet count between 70 and 397 x 109/l.

Topics: Adenine Nucleotides; Adult; Aged; Aged, 80 and over; Arachidonic Acid; Blood Platelets; Collagen; Epinephrine; Female; Humans; Male; Middle Aged; Myelodysplastic Syndromes; Platelet Aggregation; Prognosis; Ristocetin