[Thrombocytosis in patients treated with low-molecular-weight heparin: more common than imagined?]

Use of low-molecular-weight heparin (LMWH) is widespread. Clinicians are well aware of LMWH-related thrombopenia, but reports of thrombocytosis are more exceptional. We evaluated prospectively the incidence of thrombocytosis (>450 G/L) in the general medicine setting among patients needing LMWH treatment.

We followed for the duration of treatment 95 consecutive patients receiving LMWH and managed in a general medicine setting. Thrombotic events, bleeding and platelet counts were noted.

Among the 95 patients, 29 developed thrombocytosis during the follow-up (587±102 G/L). In 15 patients, thrombocytosis occurred early after discharge ; in 14 others the counts rose to a pathological level on average 5.4±0.7 days after discharge then returned to normal levels spontaneously in 10.7±7.9 days. Only one clinical event (erysipelas) was reported, potentially associated with this thrombocytosis. There were no thrombotic or hemorrhagic events during the follow-up.

In our population, the observed cases of thrombocytosis were moderate. Incidence was however not exceptional despite the absence of any notable adverse event, in agreement with the rare data in the literature.