Platelet function and its clinical significance in the myelodysplastic syndromes.

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.