Low-molecular-weight heparin overdose: management by observation.

OBJECTIVE

To describe 3 episodes of low-molecular-weight heparin (LMWH) overdose in 2 patients and discuss the clinical presentations, outcomes, and therapeutic options.

CASE SUMMARIES

The first patient, a 35-year-old female, presented after an intentional overdose of 72,000 units of dalteparin. The peak measured anti-Xa activity was 6.2 U/mL at 7.5 hours postinjection. No interventions were performed and there were no bleeding complications. The patient presented 20 days later following another overdose of 72,000 units. Anti-Xa activity was 4.5 U/mL 2 hours postinjection. No treatment was given and the patient was discharged with plans for follow-up the next day. There was no evidence of bleeding complications on follow-up. The second patient, a 29-year-old male, presented after an intentional overdose of 480 mg of enoxaparin. The anti-Xa activity was 1.9 U/mL measured 2 hours postinjection. The patient was observed without intervention. There were no bleeding complications.

DISCUSSION

To our knowledge, there is only one previous report of an LMWH overdose in the literature, an iatrogenic overdose in an infant treated with protamine. In our 3 presented episodes of LMWH overdose, no therapeutic interventions were performed and there were no bleeding complications. Review of the literature regarding the efficacy of protamine and recombinant factor VIIa for reversal of LMWH coagulopathy revealed that protamine is only partially effective and recombinant factor VIIa is effective in in vitro studies and case reports.

CONCLUSIONS

In cases of LMWH overdose, observation seems to be appropriate in the absence of clinically significant bleeding. Prolonged monitoring may be necessary for patients with renal failure. Use of protamine or recombinant factor VIIa is not supported by this case series in patients without significant bleeding. There is a lack of data regarding how to treat patients with significant bleeding.