Safety of Low Dose Enoxaparin in Thrombocytopenic Hematopoeitic Stem Cell Recepients: A Single Institution’a Case Series.

When faced with a severely thrombocytopenic cancer patient with acute or chronic thrombus, oncologists often avoid antithrombotic treatment until the platelet count is above 50 x 10⁹/L. Few attempts have been made to examine the feasibility of safely administering low-molecular-weight-heparins (LMWHs) in the presence of concurrent thrombocytopenia. We retrospectively investigated the safety of low-dose LMWH in hematopoeitic stem cell transplantation (HSCT) patients, a population at risk of bleeding. Our initial experience with the safe use of the LMWH enoxaparin in an HSCT patient published in 2002 (

Table 1. Baseline characteristics of the study patients (n=26)

Two patients received enoxaparin twice during 2 successive thrombocytopenic periods, thereby accounting for 28 safety evaluations. Subcutaneous enoxaparin 40 mg once daily was given in 85% (22/26) of the cohort. Minor bleeding occurred in 4 patients (15%) whereas major episodes developed in 2 patients (8%). These two patients experienced retroperitoneal bleeding during the transition full/low- dose anticoagulation. Dose/platelet count at the time of bleeding were: 2.35 mg/kg/d and 81 x 10⁹/L, and 1.15 mg/kg/d and 52 x 10⁹/L in the first and second patient respectively. The latter patient had an elevated serum creatinine at 2 mg/dl. The mean number of platelets days < 55 x 10⁹/L and < 20 x 10⁹/L were 16.5 days (95% CI=8.04–24.96) and 4.14 days (95% CI=2.35–5.93) respectively. The mean number of platelet transfusion was 4.93 (95% CI=2.65–7.21). The mean number of low-dose enoxaparin administration days when platelet < 55x 10⁹/L and 20 x 10⁹/L were 9.89 days (95% CI= 3.26–16.53) and 2.25 days (95%CI=0.57–3.93) respectively. The mean number of enoxaparin interruptions during thrombocytopenia was 2.75 days (95%CI=1.11–4.39). During thrombocytopenia, the median 4-hour post-dose anti-Xa level was 0.28 units/ml (range:0.04–0.4 units/ml; n=5). The present case series descriptively suggests that low-dose enoxaparin may be safely administered platelet count in the range of 20–55 x 10⁹/L in HSCT patients who weigh > 55 Kg. The safety of low-dose LMWHs below 20 x 10⁹/L remains to be established. Importantly, the transition from/to low-dose enoxaparin should be done at a higher platelet count threshold than 55 x 10⁹/L, all the more in the presence of compromised renal function.

Table 1. Baseline characteristics of the study patients (n=26)