Osteoporosis

Info

🌱 來自: Huppert’s Notes Osteoporosis🚧 施工中

Osteoporosis

•   Bone biology:

-   Osteoblasts promote bone formation and osteoclasts promote bone absorption/breakdown. Bone remodeling is a balance of osteoblast and osteoclast activity

-   Inflammatory diseases cause the upregulation of RANK-ligand, which activates osteoclasts and drives bone loss

•   Risk factors:

-   Older age, gender (F>M, accelerated bone loss after menopause due to decreased estrogen), past fractures, family history of osteoporosis, low BMI, smoking, alcohol use, prolonged steroid use

-   Medical conditions: Endocrine disorders (e.g., hyperthyroidism, Cushing’s, hypogonadism), GI disorders (e.g., IBD, celiac disease, post gastric bypass), rheumatologic disorders (e.g., rheumatoid arthritis)

•   Screening:

-   Screen all women >65 yr; consider screening younger women if risk factors for osteoporosis (fragility fracture, low BMI, high risk medication use)

-   Per USPSTF screening guidelines, there is insufficient evidence to recommend universal screening in men but can consider screening if risk factors for osteoarthritis

•   Diagnosis:

-   DEXA: Measures tissue absorption of photons to calculate the bone mineral density (BMD)

-   WHO diagnostic criteria for osteoporosis based on DEXA score:

•   T score >-1.0: Normal bone density

•   T score -1.0 to -2.5: Osteopenia

•   T score ←2.5: Osteoporosis

-   Fracture Risk Assessment Tool (FRAX): Estimates 10-yr probability of fracture if no bone-directed treatment is initiated; incorporates DEXA femoral neck bone mineral density and risk factors

•   Treatment:

-   Treatment indicated if osteoporosis or osteopenia AND history of hip or vertebral fracture, 10-yr risk of hip fracture >3% or 10-yr risk of any osteoporosis fracture >20%

-   Universal recommendations:

•   Lifestyle modifications: Exercise, smoking cessation, limiting alcohol intake

•   Calcium supplementation (typically 1200 mg daily)

•   Vitamin D supplementation (typically 800 IU daily)

-   Bisphosphonates:

•   Most common first-line therapy for osteoporosis

•   Mechanism: Inhibits osteoclasts

•   Examples: Alendronate (Fosamax) 5 mg daily or 35 mg weekly orally; ibandronate (Boniva); risedronate (Actonel); zolendronic acid (Reclast, IV formulation)

•   Administration: Most oral bisphosphonates are taken once a week, 30 minutes before eating (need to take on an empty stomach). Consider stopping after 5 yr of treatment.

•   Check calcium and vitamin D before and during treatment and ensure replete

•   Side effects: Heartburn, esophageal irritation, osteonecrosis of the jaw (ensure preventative dental work done prior to starting treatment), atypical sub-trochanteric femur fracture (presents with thigh pain, may be bilateral)

•   Contraindication: Pregnancy, CKD

-   Raloxifene (Evista):

•   Mechanism: Serum estrogen receptor modulator that inhibits bone resorption

•   Clinical use: Only useful in vertebral osteoporosis

•   Side effects: Hot flashes, DVT, leg cramps

•   Contraindications: Pregnancy, prior DVT/PE

-   Calcitonin:

•   Mechanism: Inhibits osteoclasts

•   Administration: Given as a daily intranasal spray

•   Side effects: Risk of anaphylaxis

-   Denosumab (Prolia):

•   Mechanism: Anti-RANK ligand, inhibits osteoclasts

•   Side effects: Hypocalcemia, osteonecrosis of the jaw, atypical sub-trochanteric femur fractures

•   Contraindications: Pregnancy

-   Teriparatide (Forteo):

•   Mechanism: Increases bone remodeling, analog of PTH

•   Administration: Daily injection. Should not be administered for more than 2 yr in duration

•   Side effects: Nausea, leg cramps, dizziness

•   Monitoring: Repeat DEXA 2 yr after initiating treatment