Screening for Osteoporosis
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《新英格兰医药杂志》
To the Editor: Raisz (July 14 issue)1 does not discuss a common risk factor for osteoporosis: long-term heparin administration during pregnancy. There are a number of preexisting indications (such as a history of deep-vein thrombosis) or contemporaneous indications (such as some thrombophilias or the presence of antiphospholipid antibodies with recurrent pregnancy loss) for low-dose or adjusted-dose heparin prophylaxis to be given throughout pregnancy.2 There are also conventional indications for treatment, such as new-onset deep-vein thrombosis during pregnancy. To obviate heparin-associated osteoporosis, the use of one of the low-molecular-weight heparins, calcium and vitamin D supplementation, and weight-bearing exercise are recommended.3,4
Gary F. Cunningham, M.D.
University of Texas Southwestern Medical Center
Dallas, TX 75390-9032
gary.cunningham@utsouthwestern.edu
References
Raisz LG. Screening for osteoporosis. N Engl J Med 2005;353:164-171.
Thromboembolism in pregnancy. ACOG practice bulletin no. 19. Washington, D.C.: American College of Obstetricians and Gynecologists, August 2000.
Thyroid and other endocrine disorders. In: Cunningham FG, Leveno KJ, Bloom SL, et al. Williams obstetrics. 22nd ed. New York: McGraw-Hill, 2005:1199.
Ginsberg JS, Bates SM. Management of venous thromboembolism during pregnancy. J Thromb Haemost 2003;1:1435-1442.
The author replies: Long-term heparin administration and pregnancy may be associated with an increased risk of osteoporosis and fragility fractures. Low-molecular-weight heparin appears to be safer than unfractionated heparin1,2 but still can inhibit bone formation.3,4 The synthetic antithrombotic agent, fondaparinux, was found to have no inhibitory effect on osteoblasts,4 and might be considered in patients at high risk for bone loss and fractures.
The Institute of Medicine recommends that pregnant women take a daily minimum of 1000 mg of calcium and 200 U of vitamin D, but also suggests that women who are pregnant during their pubertal growth phase — that is, women under 18 years of age — take 1300 mg of calcium daily. Calcium should be taken in divided doses; it is recommended that no more than 500 to 600 mg be taken at one time. Higher levels of vitamin D may be appropriate in pregnancy. In a recent study, the rates of bone loss in pregnancy, as measured by quantitative ultrasonography of the calcaneus, were found to be higher in the winter months, when vitamin D levels tend to fall.5
Lawrence G. Raisz, M.D.
University of Connecticut Health Center
Farmington, CT 06030
raisz@nso.uchc.edu
References
Pettila V, Leinonen P, Markkola A, Hiilesmaa V, Kaaja R. Postpartum bone mineral density in women treated for thromboprophylaxis with unfractionated heparin or LMW heparin. Thromb Haemost 2002;87:182-186.
Schulman S, Hellgren-Wangdahl M. Pregnancy, heparin and osteoporosis. Thromb Haemost 2002;87:180-181.
Hurley MM, Kream BE, Raisz LG. Structural determinants of the capacity of heparin to inhibit collagen synthesis in 21-day fetal rat calvariae. J Bone Miner Res 1990;5:1127-1133.
Handschin AE, Trentz OA, Hoerstrup SP, Kock HJ, Wanner GA, Trentz O. Effect of low molecular weight heparin (dalteparin) and fondaparinux (Arixtra) on human osteoblasts in vitro. Br J Surg 2005;92:177-183.
Javaid MK, Crozier SR, Harvey NC, et al. Maternal and seasonal predictors of change in calcaneal quantitative ultrasound during pregnancy. J Clin Endocrinol Metab 2005;90:5182-5187.
Gary F. Cunningham, M.D.
University of Texas Southwestern Medical Center
Dallas, TX 75390-9032
gary.cunningham@utsouthwestern.edu
References
Raisz LG. Screening for osteoporosis. N Engl J Med 2005;353:164-171.
Thromboembolism in pregnancy. ACOG practice bulletin no. 19. Washington, D.C.: American College of Obstetricians and Gynecologists, August 2000.
Thyroid and other endocrine disorders. In: Cunningham FG, Leveno KJ, Bloom SL, et al. Williams obstetrics. 22nd ed. New York: McGraw-Hill, 2005:1199.
Ginsberg JS, Bates SM. Management of venous thromboembolism during pregnancy. J Thromb Haemost 2003;1:1435-1442.
The author replies: Long-term heparin administration and pregnancy may be associated with an increased risk of osteoporosis and fragility fractures. Low-molecular-weight heparin appears to be safer than unfractionated heparin1,2 but still can inhibit bone formation.3,4 The synthetic antithrombotic agent, fondaparinux, was found to have no inhibitory effect on osteoblasts,4 and might be considered in patients at high risk for bone loss and fractures.
The Institute of Medicine recommends that pregnant women take a daily minimum of 1000 mg of calcium and 200 U of vitamin D, but also suggests that women who are pregnant during their pubertal growth phase — that is, women under 18 years of age — take 1300 mg of calcium daily. Calcium should be taken in divided doses; it is recommended that no more than 500 to 600 mg be taken at one time. Higher levels of vitamin D may be appropriate in pregnancy. In a recent study, the rates of bone loss in pregnancy, as measured by quantitative ultrasonography of the calcaneus, were found to be higher in the winter months, when vitamin D levels tend to fall.5
Lawrence G. Raisz, M.D.
University of Connecticut Health Center
Farmington, CT 06030
raisz@nso.uchc.edu
References
Pettila V, Leinonen P, Markkola A, Hiilesmaa V, Kaaja R. Postpartum bone mineral density in women treated for thromboprophylaxis with unfractionated heparin or LMW heparin. Thromb Haemost 2002;87:182-186.
Schulman S, Hellgren-Wangdahl M. Pregnancy, heparin and osteoporosis. Thromb Haemost 2002;87:180-181.
Hurley MM, Kream BE, Raisz LG. Structural determinants of the capacity of heparin to inhibit collagen synthesis in 21-day fetal rat calvariae. J Bone Miner Res 1990;5:1127-1133.
Handschin AE, Trentz OA, Hoerstrup SP, Kock HJ, Wanner GA, Trentz O. Effect of low molecular weight heparin (dalteparin) and fondaparinux (Arixtra) on human osteoblasts in vitro. Br J Surg 2005;92:177-183.
Javaid MK, Crozier SR, Harvey NC, et al. Maternal and seasonal predictors of change in calcaneal quantitative ultrasound during pregnancy. J Clin Endocrinol Metab 2005;90:5182-5187.