osteoporosis

  • characterized by:
    • low bone mass,
    • microarchitectural disruption,
    • increased fragility, and susceptibility to fracture

diagnosis

• appropriate history,
• physical examination,
• standard biochemical and hematologic studies,
• measurement of bone mineral density (BMD).

risk factors

NONMODIFABLE

o advanced age (in both men and women)
o female sex
o estrogen deficiency following menopause or surgical removal of the ovaries is correlated with a rapid reduction in bone mineral density
o in men, a decrease in testosterone levels has a comparable (but less pronounced) effect
o race: European or Asian ancestry predisposes for osteoporosis
o heredity
o previous fracture
o a small stature

MODIFABLE

o Excess consumption of alcohol
o Vitamin D deficiency
o Tobacco smoking: Tobacco smoking inhibits the activity of osteoblasts.
o Malnutrition: low dietary calcium and/or phosphorus, magnesium, zinc, boron, iron, fluoride, copper, vitamins A, K, E and C.
o Under weight/inactive.
o Heavy metals: Higher cadmium exposure results in osteomalacia.
• Soft drinks.
• Long-term glucocorticoid therapy
• Proton pump inhibitors (such as lansoprazole, esomeprazole, or omeprazole) that decrease stomach acid, are a risk for bone fractures if taken for two or more years, due to decreased absorption of calcium in the stomach

Types

Primary osteoporosis – type 1

postmenopausal osteoporosis occurs in 5% to 20% of women, with a peak incidence in the 60s and early 70s. Common in women more than that in men. Because of the drop in estrogen production.

Primary osteoporosis – type 2

senile osteoporosis occurs in women or men more than 70 years of age and usually is associated with decreased bone formation along with decreased ability of the kidney to produce 1,25(OH)2D3.
Vitamin D deficiency --> decreased calcium absorption --> increased PTH level and bone resorption.
In type 2 osteoporosis, cortical and trabecular bone is lost, primarily leading to increased risk of hip, long bone, and vertebral fractures.

Secondary osteoporosis – type 3

occurs equally in men and women and at any age. In men, most cases are due to diseases ( gastrointestinal, bone marrow disorders, endocrinopathies, malignancy) or to drug therapy, but in 30% to 45% of affected individuals no cause can be identified. Corticosteroid Therapy is a Common Cause of Secondary Osteoporosis

  • Basic laboratory tests:
    • Complete blood count
    • Serum chemistry levels: creatinine, calcium, electrolites
    • Liver function tests
    • Thyroid-stimulating hormone level:
    • 25-Hydroxyvitamin D level
    • Serum protein electrophoresis

bone density

treatment

  • LIFESTYLE MEASURES:
    • Calcium/vitamin D
    • Diet
    • Exercise
    • Cessation of smoking
  • Pharmacotherapy
    recommendations:
    History of hip or vertebral fracture.
    T-score ≤-2.5 (DXA) at the femoral neck or spine.
    T-score between -1 and -2.5 at the femoral neck or spine, and a 10-year probability of hip fracture depending on the country: ≥3 percent or a 10-year probability of any major osteoporosis-related fracture ≥20 percent based upon the United States-adapted WHO algorithm.
  • ANTIRESORPTIVE THERAPY:
    oral bisphosphonates as first-line therapy – risendronate, alendronate, ibandronate, zolendronate (ONJ – osteonecrosis of the jaw)
    denosumab – a humanized monoclonal antibody against RANKL that reduces osteoclastogenesis
    Odanacatib – inhibitor of Catepsin K (lysosomal protease)
  • ANABOLIC THERAPY:
    Teriparatide – is effective (subcutaneously) at increasing BMD in postmenopausal and glucocorticoid- induced osteoporosis and is more effective than alendronate at reducing the incidence of vertebral and hip fractures
    selective estrogen receptor modulators (SERM):Specific to Post-Menopausal Women
     strontium ralenate – divalent strontium ions have the capacity to substitute for calcium within bone without adversely affecting mineralization
  • bone mineral density (BMD) ≥2.5 standard deviations below the peak bone mass for young adults (i.e. T-score ≤–2.5)
  • osteopenia: BMD with T-score between -1.0 and -2.5

Features

  • commonly asymptomatic.
  • fractures: most commonly in hip, vertebrae, humerus, and wrist
    x-ray: vertebral compression and crush fractures, wedge fractures, “cod shing” sign (weakening of subchondral plates and expansion of intervertebral discs)
  • pain, especially backache, associated with fractures

Indications for testing

 people over age 50 with any of the following:
• previous fracture from minor trauma
• rheumatoid arthritis
• low body weight
• a parent with a hip fracture
• Prolonged use of glucocorticoids
• Hypogonadism or premature menopause
• Primary hyperparathyroidism
• Vertebral fracture or osteopenia identified on x-ray
• Current smoking
• High alcohol intake

All women and men age ≥ 65 yr

  • Clinical Signs of Fractures or Osteoporosis
    • Height loss >3 cm (Sn 92%)
    • Weight <51 kg
    • Kyphosis (Sp 92%)
    • Tooth count <20 (Sp 92%)
    • Grip strength
    • Armspan-height difference >5 cm (Sp 76%)
    • Wall-occiput distance >0 cm (Sp 87%)
    • Rib-pelvis distance 2 finger breadth (Sn
    88%)

Fragility fracture: fracture that occurs following fall from standing height or less or with no trauma.