Defective Platelet Aggregation in Myelodysplastic Syndromes

Introduction: Hemorrhagic tendency in patients with myelodysplastic syndrome (MDS) is mainly attributed to thrombocytopenia. However, platelet function in these patients has not been thoroughly investigated.

Aim: The aim of our study is to evaluate platelet function in patients with primary MDS.

Methods: Platelet function was studied with aggregometry in response to ristocetin, collagen, ADP and adrenaline in 26 MDS patients and 15 healthy individuals.

Results: 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.

Conclusions: 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.