322 Obstetrics and Gynecology Board Review •••
❍ How does estrogen therapy help maintain bone mass?
A direct effect on osteoblasts, improved intestinal absorption of calcium, and decreased renal excretion of calcium.
❍ What is the total calcium requirement to minimize bone loss in postmenopausal women not taking estrogen
replacement?
1500 mg.
❍ What is the total calcium requirement to minimize bone loss in women on estrogen replacement therapy?
1200 mg.
❍ In addition to calcium, in women over the age of 70, what other supplementation should be included for
osteoporosis fracture prevention?
Vitamin D 800 IU, especially if in Northern latitudes.
❍ Does skim milk have less calcium than whole milk?
No. Since calcium is water-soluble skim milk has more calcium than whole milk.
❍ What disease process can be unmasked with high calcium supplementation?
Asymptomatic hyperparathyroidism.
❍ What other agents are known to reduce bone resorption?
Calcitonin, fluoride, androgens and bisphosphonates (etidronate disodium, risedronate, alendronate), SERMS
(selective estrogen receptor modulators such as raloxifene).
❍ Why is not calcitonin more widely used for osteoporosis?
It is expensive and must be administered parenterally or nasally, and it is effective only against vertebral fracture
reduction.
❍ How often are vertebral compression fractures asymptomatic?
60% to 66% of the time.
❍ How many osteoporotic fractures occur each year in the United States?
Approximately 1.3 million.
❍ How many of these are vertebral fractures?
About 50%. Hip fractures account for another 25%.
❍ What percentage of Caucasian women will experience a hip fracture?
20%.
❍ What percentage of bone is resting at any one time?
88.