Occasionally, a patient is treated with long-term low molecular weight heparin (LMWH) (enoxaparin = Lovenox®; Dalteparin = Fragmin®; Tinzaparin = Innohep®) for months or years. LMWH may be given because the patient (a) tolerated warfarin poorly (widely fluctuating INRs; significant side-effects, such as marked hair loss or fatigue), (b) had a recurrent clot which occured on warfarin with a therapeutic INR, or (c) is pregnant and LMWH is the preferred “blood thinner” during pregnancy in women at increased risk for blood clots. The main side-effect of long-term LMWH is, of course, bleeding.
Whether LMWH causes osteoporosis (=loss of bone mass) is not known, as it has not been appropriately studied. A recent detailed review of the literature concluded that (a) based on the evidence of reported cases and studies there may be a small impact of LMWH on osteoporosis, (b) no large studies have been done to investigate the effect of prolonged LMWH on bone density, (c) large well-designed clinical trials are needed to determine whether LMWH contributes to osteoporosis, and (d) it is impossible to say whether calcium supplementation is beneficial or not in patients treated long-term with LMWH.
My personal approach
In the absence of clinical trial data guiding physicians what’s right to do in the patient on long-term LMWH, I (a) recommend a once yearly bone density study (DEXA scan), and (b) encourage intake of daily calcium supplementation. No data whatsoever are available on long-term use of fondaparinux (Arixtra®) and osteoporosis. As with LMWH, I recommend a yearly bone density study and calcium supplementation.
Lefkou E et al. Low-molecular weight heparin-induced osteoporosis and osteoporotic fractures: A myth of an existing entity? Lupus 2010;19:3-12.
Disclosure: I do not have a financial conflict of interest with the content of this post.
Last updated: June 22nd, 2011