OSTEOPOROSIS
GENERAL FEATURES
• Osteoporosis is characterized by reduced bone mass with deterioration of structure, resulting in bone fragility and fractures.
• Bone resorption occurs faster than bone formation.
• Osteoporosis affects more than 10 million Americans, mostly females.
• Two main types of osteoporosis:
–Primary
■ Postmenopausal osteoporosis affects primarily the trabecular bone (vertebrae, wrist, hip).
■ Age-related osteoporosis affects women and men; trabecular and cortical bone are involved.
–Secondary
■ Premenopausal osteoporosis affects those with genetic factors and poor nutrition; it is related to the presence or treatment of other systemic disease.
• A combination of aging and decreased estrogen levels accelerates bone loss:
–Peak bone mass is reached in the late 20s and early 30s.
–Bone density decreases by 1% to 2% per year in postmenopausal women.
• The most common sites of osteoporotic fractures are vertebral bodies, wrist/distal radius, and the hip.
CLINICAL ASSESSMENT
• History
–Risk factors include estrogen deficiency, white and Asian race, family history, low body weight, smoking, alcohol use, history of corticosteroid use, inadequate physical activity, endocrine disorders, and malabsorption.
–Vertebral fractures may be asymptomatic but can result in a loss of height up to 6 inches.
–Pain and/or radiculopathy are often present, although most patients are asymptomatic.
• Symptoms
–Patient may have kyphosis (dowager's hump) from fractured vertebrae.
–If secondary causes are present, signs of endocrine disorders may be present.
–Bony tenderness over vertebrae and/or height loss suggest possible compression fracture.
DIAGNOSIS
• Alkaline phosphatase and renal function measurements and calcium levels can rule out other causes.
• Bone mineral density (BMD) testing
–Dual-energy x-ray absorptiometry (DEXA) measures density of the spine and hip and is considered the gold standard.
■ Results are reported as a T-score; the lower the bone density, the lower the T-score (normal, T-score ≥1; osteopenia, T-score of -1 to -2.5; osteoporosis, T-score <-2.5)
–DEXA scan recommendations
■ Postmenopausal women >65 years: every 2 years
■ Postmenopausal women <65 years with risk factors or fracture
■ Women with medical conditions and/or medications that increase risk
• Quantitative computed tomography offers three-dimensional BMD; cost is high and availability is limited.
TREATMENT
• Bisphosphonates (alendronate [Fosamax, generics], ibandronate [Boniva], zoledronic acid [Zometa]) are considered the first-line therapy for management of menopause-associated bone loss.
–They reduce bone resorption through the inhibition of osteoclastic activity.
–Weekly, monthly, and yearly preparations are available.
–Rare side effects include esophagitis, osteonecrosis of the jaw, and avascular necrosis.
• Selective estrogen receptor modulators (SERMs)
–Raloxifene (Evista) is one type.
–Nonhormonal options exist that exhibit estrogen receptor agonist activity in the bone.
–They reduce spinal fracture risk, but bisphosphonates work better.
• Calcitonin salmon (Miacalcin) slows the rate of bone loss and has a moderate analgesic effect; less effective than bisphosphonates.
• Exogenous parathyroid hormone (Teriparatide [Forteo])
• Hormone therapy
–Estrogen preserves bone, increases mass, and increases absorption of calcium.
• Prevention
–Take 1,500 mg/d of calcium.
–Vitamin D (600-800 IU/d) helps the body absorb calcium.
–Low-impact aerobic activity and weight-bearing and muscle strengthening exercises help.
–Smoking cessation
–Take precautions to prevent falls.
–Avoid medications that promote bone loss (eg, glucocorticoids).
QUESTION & ANSWER
1. A 60-year-old postmenopausal woman is evaluated in the emergency department after a fall on an outstretched
hand. A Colles fracture is diagnosed. In addition to managing her acute injury, what further outpatient
testing is recommended for this patient?
a. Spine and hip radiograph
b. DEXA scan
c. Serum parathyroid level
d. No further testing is recommended
Answer: b
Explanation: The patient has sustained a fracture to the distal radius, a common site for an osteoporotic fracture. She should be evaluated for osteopenia and osteoporosis with a DEXA scan.