Osteoporosis Armed Forces Academy of Medical Sciences

Interpreting DXAs 56 y/o F with hyperparathyroidism Need to follow DXA on regular basis Pt on alendronate—is it working? How do we interpret changes in BMD?

Interpreting DXAs DENSITY T-SCORE Z-SCORE (gm/cm2) Lumbar spine L1-L4: Left femoral neck: Total left proximal femur: DENSITY T-SCORE Z-SCORE (gm/cm2) The lumbar spine (L1,L2,L3,L4) The left femoral neck Total Left Proximal Femur DXA from 30 JAN 08 DXA from 14 APR 06

Interpreting DXAs First, make sure the study was done on the same machine Next, make sure you are comparing same anatomic regions Will compare BMD, not T or Z scores Know what is a significant change for your center. This used to be included on reports but is not anymore

Least Significant Change Get by scanning 30 pts twice and calculating technician’s standard deviation Recently done at our center:  Spine: gm/cm2  Total Hip: gm/cm2 This is very good—too good?

Interpreting DXAs 2008:Lumbar spine L1-L4: : The lumbar spine (L1-L4) Difference: or about 2% Change at femoral neck is 0.003

Interpreting DXAs DXA report stated: “A baseline DEXA scan was performed on 4/14/06. The change in bone mineral density (BMD) in the lumbar spine was calculated based on L1-L4. Change in BMD in the lumbar spine: -7.5%, which corresponds to 1.2% per year. Change in BMD in the total left femoral neck: -6.8%, which corresponds to -1.1% per year.”

So who’s right? Other DXAs Spine Change from % 8% 20% So what can we say about her BMD?

Interpreting DXAs Over the past 4 yrs, BMD has been stable at the hip and slightly decreased at the spine Has been on alendronate since 2001 What do you expect to see happen to BMD on serial DXAs when on a bisphosphonate

FLEX trial Black et al, JAMA DEC 2006: 296:

Markers of Bone Turnover Black et al, JAMA DEC 2006: 296:

FLEX Trial In women who discontinued therapy after 5 years, BMD remained at or above baseline values 10 years earlier and bone turnover was still somewhat reduced. Discontinuation did not increase the risk of nonvertebral fractures or x-ray detected vertebral fractures over the next 5 years, but the risk of clinically diagnosed vertebral fractures was significantly increased among those who discontinued These results suggest that for many women, discontinuation of alendronate after 5 years for up to 5 more years does not significantly increase fracture risk, but women at high risk of clinical vertebral fractures, such as those with vertebral fracture or very low BMD, may benefit by continuing beyond 5 years.

Evaluating Bisphosphonate Therapy How often do you need to do DXAs? Is it OK to stop therapy? What about side effects?  Osteonecrosis of the jaw Whom should you treat?

FRAX website onValue=2 onValue=2 If 10 yr risk is >20% for a major osteoporotic fracture, or >3% for hip fracture, should consider treating. Most helpful to risk stratify and avoid treating pts who are at low risk for fx. Someday this may be incorporated into DXA reports

Limitations Does not take into account spine BMD Does not take into account other predisposing medical conditions such as other medications

New Player Receptor activator of nuclear factor-kappaB ligand (RANKL) is a cytokine member of the tumour necrosis factor family that is the principal final mediator of osteoclastic bone resorption. It plays a major role in the pathogenesis of postmenopausal osteoporosis, as well as bone loss associated with rheumatoid arthritis, metastatic cancer, multiple myeloma, aromatase inhibitor therapy and androgen deprivation therapy. Denosumab (AMG 162) is an investigational fully human monoclonal antibody with a high affinity and specificity for RANKL. By inhibiting the action of RANKL, denosumab reduces the differentiation, activity and survival of osteoclasts, thereby slowing the rate of bone resorption. Denosumab has been shown to increase bone mineral density (BMD) and reduce bone turnover in postmenopausal women with low BMD. Denosumab is a potential treatment for osteoporosis and other skeletal disorders

Denosumab In a double-blind, head-to-head study with alendronate in post-menopausal women with low bone mineral density (BMD), denosumab achieved significantly greater BMD gains at the total hip, hip trochanter, and distal radius. BMD improvement at the total hip was approximately 40% greater in the denosumab treatment arm compared with those receiving alendronate (primary endpoint). Twice-yearly injections of denosumab also achieved significant increases in BMD in a pivotal 332-patient study, in which it was compared with placebo. At the end of the two-year study period, denosumab-treated patients had a significantly greater increase in lumbar spine BMD compared with placebo recipients (6.5 vs -0.6%; p<0.001). Similar significant differences were observed between active treatment and placebo with respect to BMD at the total hip (3.4 vs -1.1%; p <0.0001), wrist (1.4 vs -2.1%; p<0.0001) and total body (2.4 vs -1.4%; p<0.0001). Treatment with denosumab appeared well tolerated by patients enrolled in clinical trials performed to date.

Secondary Causes of Osteoporosis When do you look for secondary causes? What is the usefulness of the Z score?

Secondary Causes Hyperthyroidism Hyperparathyroidism Cushings Hypogonadism Vit D defic Medications: Steroids, heparin, dilantin Hypercaciuria Chronic renal failure Multiple myeloma

Work-up Serum and 24 hr urine calcium TFTs PTH Testosterone 25-Vit D SPEP/UPEP ?Cushings eval