Sunday 1 December 2013

Osteoporosis - treatment - estrogen receptor modulators, calcium

Selective estrogen agonists/antagonists (estrogen receptor modulators):
Raloxifene exerts favourable response in bone & lipids by estrogen agonist effect but no proliferative effect on the endometrium.
App 50% reduction in vertebral fractures, data about protection against hip fracture is lacking. Increase in bone density & decrease in fracture rate is more with alendronate.
Tamoxifen & raloxifene reduced the incidence of breast cancer within 2-3yrs of treatment. Raloxifene also exerts protection against coronary artery atherosclerosis.
Neutral impact on insulin sensitivity & glucose metabolism, sexual function & cognition. Raloxifene is option in pts reluctant to hormone therapy, but it is not a substitute for estrogen.

 Calcium supplimentation:
Calcium absorption decreases with age because of decrease in biologically active vit D.
As average dietary intake is 500 mg per day, Calcium supplementation of 500mg/day is needed in women with estrogen therapy and 1000 mg in women not on therapy to reduces bone loss and decrease in fractures.
If supplementary dose is more than 500 mg daily blood levels of calcium and phosphorus to be measured yearly for the first 2 yrs to rule out asymptomatic hyperparathyroidism.
Estrogen improves calcium absorption there by decreases side effects related higher doses as constipation, flatulence, decreased compliance etc.
Improved calcium intake in adolescence provides protection against osteoporosis in life.
Calcium carbonate tablets are cheapest and contain most elemental calcium (40%).
Cal lactate 13%, cal citrate 23%, cal gluconate 9%.
Aluminium containing antacids reduce cal absorption.
Calcium supplementation is most effective when taken with meal.
Cal citrate is best choice for older pts with reduced gastric acid production. Excess cal can lead to slight increase in kidney stones.

Changes of bone remodeling
Pathophysiology
Signs and symptoms
Risk factors and investigations
Investigations
Diagnostic tests and biochemical markers
Hormonal treatment
Estrogen modulators, calcium
Vitamin D
Bisphosphonates
Calcitonin, Fluoride, Tibolone
Prevention

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