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As estrogen declines, osteocytes become numerous and osteoblasts decrease. This leads to more bone remodelling with less cells to fill in the pits created by the osteoclasts.
Rounding of the spine that leads to a slouching look. Can be caused by vertebral wedging, bi-concave fractures & crushed or scalloped end-plates.
Uses bone mineral density combined with age & the number of risk factors/fractures to identify relative risk for osteoporosis.
Tests for bone mineral density
- Quantitative computed tomography (QCT) - allows separate evaluation of cortical (compact) & trabecular (spongy, canellous) bone. Good, but expensive.
- DEXA - most common
- Quantitative ultrasonography of heel - correlation w. osteoporosis of spine & hip
- Small positive effect on BMD.
- Calcium citrate - absorbed better (only 21% elemental Ca)
- Calcium carbonate - won't absorb if on H2 blocker or PPI, must be taken with food. (40% elemental Ca)
- May increase chances for MI
Vitamin D treatment
Looks like it only works to prevent vertebral and hip fractures if above 30 ng/ml serum concentration.
TZDs and antidepressants
Increase risk for fractures, particularly in the hip and wrist.
Prevent osteoclasts from working s wekk & stop the remodelling of bone. Estrogen, calcitonin, raloxifene & bisphosphanates.
- Ihibit osteoclast-mediated bone resorption by making osteoclasts not work as well & initiating apoptosis.
- Boniva, Actonel, alendronate & other names that end in -dronate.
- Can't take with food, can get esophagitis (drink with big glass of water)
- Cannot use more than 10 years because pts. can get increased risk of fractures due to frozen bones that become brittle.
- Pts may also get osteonecrosis of the jaw (highest prevalence with zoledronate)
Increases spine & hip BMD, no reduction in racture incidence.
- (used in place of estrogen in post-menopausal women) Non-steroidal benzothiopene - binds estrogen receptor & inhibits bone resorption without increased endometrium
- Increased BMD with significant reduction in incidence of breast cancer & vertebral fractures.
Normally occurring product of the parafollicular "C" cells of the thyroid that reduces blood calcim and counteracts PTH. It also inhibits osteoclasts. Reduces chance of vertebral compression fracture. Also provides analgesic relef for acute & chronic pain from VCF.
PTH analog (Forteo - teriparatide)
- While this drug stimulates bone remodeling and resorption there is a "paradoxical effect" where, when given intermittently, it will stimulate new bone formation.
- Can lead to hypercalcemia. Don't give to pts with paget disease, hypercalcermia, skeletal malignancy. Not to be given longer than 24 months.