I. Normal bone physiology
- Postmenopausal women lose 3-4% of bone mass/yr
- Rate of bone loww is equal in men & women after age 65
- 90% of women & 50% of men have osteoporosis by 80yo
II. Pathophysiology
- Loss of bone cancellous > cortical, so get vert. compr. fx.
- Problem is mostly excessive osteoclastic activity
- Affects both men and women.
- Loss of bone cancellous = cortical, so get hip and vert. fx.
- Problem is mostly inadequate osteoblastic activity
III. Risk factors
- Corticoid excess (endogenous or exogenous; perhaps even inhaled!--Chest 106:1722, 1994)
- Hyperthyroidism, including iatrogenic (exogenous)
- Chronic renal disease, esp RTA
- Liver disease
- Hyperparathyroidism
- Multiple Myeloma, leukemia, lymphoma
- Dilantin (reduces intestinal Ca absorption)
- Prolonged heparin exposure
- Celiac sprue through vit. D malabsorption
- Rheumatoid arthritis?
IV. Diagnosis
- Risk factors and secondary causes of bone loss (see above)
- Fracture history
- XRay for path. fx
- Px: look for spinal kyphosis, pain, immobility
- Quantitative CT---can check cortical or trabecular bone; high radiation dose, often imprecise
- Dual photon abs.-can check all bones; slow and expensive
- Dual energy xray absorptiometry ("DEXA")-better reproducibility than DPA, but expensive; usually check lumbar vertebrae or prox. femur
- Usually report both a "z-score" (# of SD's from mean of age/sex-matched population) and "t-score" (# of SD's from mean in healthy young gender-matched adults).
- WHO defines "Osteopenia" as t-score of -1 to -2.5 and "osteoporosis" as t-score < -2.5
- In one prospective study comparing u/s of calcaneus with DEXA of calcaneus and hip in 5,000 women over 65yo followed for avg. of 2y, predicted fractures (hip & elsewhere) to a similar degree as DEXA (Arch. Int. Med 157:629, 1997-JW)
V. Prevention:
- 800mg/d 4-8yo
- 1300mg/d 9-18yo
- 1000mg/d 19-50yo
- 1200mg/d > 50yo
- Dietary sources
- Usually sufficient but supplements may be required for those who won't/can't take dairy
- About 300 mg of Ca in 8oz yogurt, 1cup milk, 1.5oz cheddar cheeze, 2oz American cheese, 5oz canned salmon, 3/4 cup tofu, 10 figs, 6 sardines, or 1cup collared greens. Calcium in wheat bran or spinach is poorly absorbed
- Supplemental Calcium
- CaCO3 has good bioavailability; cheap; absorption best if taken with meals; take at night to coordinate with diurnal rhythms of bone mineralization; contraindicated in hypercalemia, sarcoid, nephrolithiasis (CaCitrate 950mg QD better in latter case)
- CaCO3 500mg = 200mg elemental Ca
- CaCitrate 950mg = 200mg elemental Ca (slightly more bioavailable than CaCO3)
- Overall bioavailability falls with doses > 500mg of CaCO3.
- Very high doses of CaCO3 can lead to the "milk-alkali" syndrome, nephrocalcinosis, and renal insufficiency
- In a study in 36,282 postmenopausal women randomized to CaCO3 1g/d + Vit. D 400IU/d vs. placebo, over 7y f/u, there was no sig. diff. in overall incidence of spine, hip, or total fractures, though among the subgroup of women not using supplemental Ca/Vit. D outside the treatment protocol, RR for hip fx was sig. lower in supplemented group (HR 0.7); ctive-tx group had sig. higher incidence of kidney stones (WHI Trial; NEJM 354:669, 2006--JW)
VI. Treatment of Osteoporosis and Ostopenia
National Osteoporosis Foundation as of 7/97 recommends tx for any postmenopausal women w/osteoporosis who has had a vertebral or hip fx, all women w/o h/o fx and T score below -1.5 if risk factors for osteoporotic fx are present (personal h/o fx as an adult, h/o fx in 1st-degree relative, caucasian, "advanced age," female, dementia, poor health/frailty, current smoker, body weight < 127lb, menopause x > 1y, low Ca intake, alcoholism, impaired eyesight despite adequate correction, recurrent falls, or inadequate physical activity), and all women w/o h/o fx and T score below -2.0.
- Estrogen--see also "Hormone Replacement Therapy"
- Probably works by reducing osteoclastic activity
- Is most effective in early postmenopausal period, e.g. <65yo, but works afterward as well
- Protective effects are lost soon after stopping drug so tx probably should be chronic
- See below for some studies on combining estrogen + bisphosphonates
- Calcitonin (100IU SC/IM QOD or 200IU intranasal QD)
- Reduces fractures c/w placebo
- Less effective at increasing bone density than estrogen
- May also provide some analgesia in pts after fracture
- Adverse effects
- Parenteral form causes flushing, skin rash, nausea, dizziness
- Intranasal form only causes nasal irritation
- Lack of response in some patients has been attributed to "low-turnover" state or perhaps b/c of antibody formation
- Inhibit bone resorption
- All persist unmetabolized in bone for months-years
- Etidronate (Didronel) 400mg QD
- Inhibits bone mineralization, so can cause osteomalacia; therefore, must be given cyclically (2wks/3mos)
- Trials through late '95 show safety & efficacy through 7y of use
- Etidronate + HRT better than either alone: 72 pts randomized to HRT (Premarin 0.625/d + norgestrel 150mg/d 12d/mo), etidronate (400mg/d x 14d every 12wks), both, or placebo; all were encouraged to exercise and tx'd with Ca (1g/d) and vit. 4 (400IU/d). Placebo group showed sl. decrease in spine & hip BMD at 2y and 4y; no change in etidronate or HRT groups; combined group showed sig. increases at both 2y and 4y; incidence of new vertebral fx (assessed by plain films) sig. less in combined group than w/placebo; hip BMD was sig. increased c/w placebo or either single-tx group (Am. J. Med. 104:219, 1998--AFP)
- Alendronate (Fosamax) 10-40mg/d (or 70mg Qwk)
- In a randomized trial in 994 postmenopausal women w/osteoporosis, 10mg QD before breakfast reduces risk of spine & hip fx compared with placebo (NEJM 333: 1437, 1495; 1995); in an extended (to 7y) f/u study in the same cohort, continued increases in BMD were seen and no serious side effects detected in women on Alendronate (J. Clin. Endoc. Metab. 85:3109, 2000--JW)
- The "Fracture Intervention Trial" (JAMA 280:2077, 1998)
- 8705 women 54-81yo with femoral neck BMD < 0.69g/cm2 (corresponds to > 1.5SD below young adult mean) but no vertebral fx randomized to alendronate (5mg/d x 2y then 10mg/d--increased after other studies suggested 10mg/d to be more effective) vs. placebo. All pts with dietary Ca intake < 1g/d received 500mg Ca & 250IU cholecalciferol as well. Over average 4.2y f/u, alendronate group had sig. higher BMD at all sites studies, nonsig. reduction in clinical fx incidence (RR 0.86--though in subgroup of women with baseline femoral neck BMD > 2.5SD below young adult mean, reduction in clinical fx was sig., RR 0.64), and sig. fewer radiographically-assessed vertebral fx (RR 0.56)
- 10mg QD ass'd with increased bone density at lumbar spine (sig.) and greater trochanter (nonsig.) in 428 osteoporotic women on postmenopausal HRT (J. Clin. Endocrin. Metab. 84:3076, 1999--JW)
- Alendronate for treatment of osteoporosis in men
- 241 men w/osteoporosis (mean age 63) randomized to alendronate 10mg/d vs. placebo; at avg. 2y f/u mean lumbar spine & femoral neck BMD was sig. more increased in the alendronate group; also, sig. fewer new vertebral fx in alendronate group (7.1% vs. 0.8%) (NEJM 343:604, 2000--JW)
- Duration of treatment with Alendronate
- In a study in 1,099 postmenopausal women on alendronate 5-10mg/d for at least 5y randomized to continued treatment vs. placebo; all took Ca/Vit. D supplementation. After 5y, there was no sig. diff. between the groups in the incidence of nonvertebral fx though alendronate group had sig. fewer symptomatic vertebral fx (2.4% vs. 5.3%) ("Fracture Intervention Trial Long-term Extention" ("FLEX"), JAMA 296:2927, 2006--JW)
- Alendronate for osteopenia
- In analsys of data from the Fracture Intervention Trial re: 3,737 postmenopausal women 55-80yo with femoral neck T-scores -1.6 to -2.5 randomized to alendronate vs. placebo x 4.5y, alendronate group had sig. reductions in both clinically recognized vertebral fx (RR 0.4) and radiologically identifiable vertebral fx (RR 0.59), though reductions were not sig. among subgroup of pts with no vertebral fx at baseline (Mayo Clin. Proc. 80:343, 2005--JW)
- Alendronate + HRT better than either alone
- 425 postmenopausal women with low BMD, mean age 61, all s/p hysterectomy and not on HRT at onset rnadomized to alendronate 10mg/d, Premarin 0.625mg/d, both, or double placebo. Over 2y f/u, combined therapy ass'd with sig. greater increase in BMD than either alone; low incidence of fx in the trial so no sig. diff. observed in fx incidence among the groups (J. Clin. Endocr. Metab. 85:720, 2000--JW)
- 373 women with osteoporosis 65-90yo randomized to alendronate, hormone therapy, both, or double-placebo; over 3y, combination therapy was ass'd with sig. greater increases in spine and hip BMD than placebo or either tx alone. (JAMA 289:2525, 2003--JW)
- No need for cyclic dosing
- Side f/x:
- Esophagitis
- May be severe
- Risk is reduced if take in am before any food, drink, or meds, with lots of H2O, and remain upright for 30min after dosing or until first food of day, whichever happens later
- 70mg Qwk dose was not ass'd with any difference in upper endoscopic findings (Am. J. Gastroent. 97:58, 2002--JW) or in GI symptoms (Mayo Clin. Proc. 77:1031, 2002--JW) in two randomized trials
- Gastric ulcer (see under Risedronate below)
- Risedronate (Actonel) 5mg PO QD or 35mg PO Qwk
- May cause mild diarrhea, nausea, and abdominal pain
- Causes arthralgias in 30%
- Causes flu-like syndrome in 10%
- Risedronate 5mg/d ass'd with sig. fewer gastric ulcers on EGD at 2wks than Alendronate 10mg/d in a randomized study inb 515 healthy postmenopausal women (4% vs. 13%) (Gastroent. 119:631, 2000--JW)
- 5445 women 70-79yo with osteoporosis and 3886 women > 80yo with non-skeletal risk factors for hip fx (poor tandem gait, difficulty in standing from a sitting position, recent falls, etc) randomized to Risedronate vs. placebo; all received Ca supplements. At 3y f/u, th osteoporosis group had sig. lower hip fx incidence with risedronate (1.9% vs. 3.2% w/placebo); in the "non-skeletal risk factor" group, there was a nonsignificant decrease in hip fx incidence (p = 0.35) (NEJM 344:333, 2001--JW)
- Risedronate + HRT better than either alone: 524 postmenopausal women randomized to HRT vs. HRT + risedronate 5mg/d; at 12mos; bone density increase was sig. greater in combination group than HRT group at femoral neck & radius but not L-spine or femoral trochanter. Fx rate was low and not sig. diff. in the tx groups (J. Clin. Endocrinol. Metab. 86:1890, 2001--JW)
- Pamidronate (Aredia) 30mg/d IV
- May cause a flu-like syndrome
- Tiludronate (Skelid) 400mg/d PO
- Clodronate--undergoing clinical trials as of 1998
- Zoledronate (Zometa, Reclast) given IV Q3mos--Increased BMD c/w placebo in one randomized trial (NEJM 346:653, 2002--JW)
- Ibandronate (Boniva) 2.5mg QD or 150mg Qmo (I have not seen any studies examining this drug's efficacy in reducing fracture incidence--ER)
- Denosumab
- A humanized monoclonal antibody to receptor activator of nuclear factor-B ligand (RANKL), a cytokine, expressed by osteoblasts; binding RANKL reduces osteoclastic activity
- In a study in 7,868 women with postmenopausal osteoporosis randomized to denosumab 60mg SQ vs. placebo Q6mos x 3y, denosumab pts had sig. lower incidence of new vertebral fx (RR 0.32) and hip fx (RR 0.6); no sig. diff. in adverse events (NEJM 361:818, 2009-JW)
- Fluoride
- Originally used after fx in osteoporotic pts
- Controlled trials showed it actually increases rates of fx, prob. b.c stimulates formation of cancellous bone at expense of cortical bone
- Slow-release formulations at lower doses may hold promise
- 200 postmenopausal women with moderately low BMD randomized to 152mg of Na-monofluorophosphate + Ca 1g vs. Ca alone with each meal; at 4y f/u MFP group had sig. higher spine BMD but no diff. in hip BMD; also sig. lower incidence of new vertebral fx (2% vs. 10%) in MFP group (Ann. Int. Med. 129:1, 1998--JW)
- Teriparatide (recombinant parathyroid hormone, "Forteo") 20ug SQ QD
- Continuous PTH administration leads to bone resorption but intermittent administration stimulates bone formation
- Use as of 2005 is recommended not to exceed 2 years--See below re: what to do after that time
- Shown to increase BMD in men as well as women
- Evidence of efficacy
- 1637 postmenopausal women with h/o atraumatic vertebral fx randomized to PTH 20ug or 40ug SQ QD vs. placebo for mean 18mos. New vertebral fx sig. less common in both PTH groups than placebo (4%, 5%, 14% in 40ug, 20ug, and placebo groups, respectively); ditto for new nonvertebral fx (6%, 6%, and 10%); side f/x sig. more common in tx than placebo group included hypercalcemia, nausea, and headache; also orthostatic hypotension with the first few doses (NEJM 344:1434, 2001--JW)
- In a study in 2,679 postmenopausal women with osteoporosis (81% of whom had no prior vertebral fracture) randomized to 100ug parathyroid hormone SQ vs. placebo QD x 18mos, PTH group had sig. greater increases in lumbar spine and hip BMD but decreased at the distal radius c/w placebo; PTH group had sig. lower incidence of new or worsened vertebral fx (1.4% vs. 3.4%). PTH recipients had sig. higher incidence of hypercalcemia and nausea (Ann. Int. Med. 146:326, 2007--JW)
- Use as an adjunct to Alendronate
- In a study in 126 women with osteoporosis all on alendronate x at least 1y randomized to daily SQ PTH x 15mos, daily SQ PTH on/off for 3-month cycles x 15mos, or no PTH; all continued alendronate during the study; at 15mos, both PTH groups had sig. greater increases in spine BMD than the alendronate-only group but there was no sig. diff. between the two PTh regimens (NEJM 353:566, 2005--abst)
- Adverse effects
- hypercalcemia, nausea, and headache; also orthostatic hypotension with the first few doses
- Associated with increased risk of osteogenic sarcoma when given to rats at high doses (Med. Lett. 45:9, 2003); avoid in patients at increased risk for osteosarcoma, e.g. Paget's disease or unexplained elevations in serum alkaline phosphatase.
- HMG CoA-Reductase inhibitors ("statins")
- Originally developed for tx of Dyslipidemias
- Several studies have shown evidence for bone density increase & decrease of fracture risk
- In a case-control study of 3940 pts with fx and about 88,000 controls, RR of fx was 0.55 for pts on a "statin" drug, after adjustment for confounders (JAMA 283:3205, 2000--JW)
- In another case-control study of 1,222 pts > 65yo with hip fx and 4,888 controls, OR of fx was 0.5 for pts who used statins in previous 6mos and 0.57 in those who had used in previous 3y; no such association w/other lipid-lowering drugs (JAMA 283:3211, 2000--JW)
- In a case-control study of 928 women > 60yo with fx and 2747 age-matched controls, pts who had had statins dispensed > 12x had OR 0.48 for fx than others (Lancet 355:2185, 2000--JW)
- In a study of 41 postmenopausal women on statins for hypercholesterolemia c/w 100 age-matched controls not on statins had sig. higher spine & hip bone density (Lancet 355:2218, 2000--JW)
- But others haven't...
- In a case-control study of 81,880 pts > 50yo with fx and 81,880 age-, sex, and practice-matched controls, OR for fx in current users of statins c/w nonusers was 1.01 (adjusted for smoking, meds & illnesses ass'd with fx risk, and BMI when known) (JAMA 285:1850, 2001--Abst)
- In a prospective observational study of 7,846 statin users and 85,870 nonusers (all women 50-79yo) followed for median 3y, after adjusting for potential confounders, there was no sig. diff. in risk for hip, lower arm or wrist, or other fractures, or bone density (Ann. Int. Med. 139:97, 2003)
2y incidence of the vertebral fracture was sig. reduced (c/w placebo) for the following treatments: estrogen/medroxyprogesterone (RR 0.35), etidronate (RR 0.40), calcitonin (RR 0.41), and vitamin K (RR 0.44) (Am. J. Med. 117:549, 2004--AFP)