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MYTH: Parathyroid hormone (PTH) breaks down bone, so PTH injections don't help treat osteoporosis.


FACT: Hyperparathyroidism, which involves PTH hypersecretion, can lead to bone demineralization and pathologic fractures. But once-daily PTH injections have the opposite effect: They stimulate new bone formation leading to increased bone mineral density. This paradoxic effect appears to be related to the rapid rise and fall of serum PTH levels when the hormone is given as an injection, in contrast to the consistently high level caused by hyperparathyroidism.


The parathyroid glands secrete PTH in response to hypocalcemia. PTH brings serum calcium levels back to normal by promoting the release of calcium from bone, enhancing intestinal absorption of calcium by increasing vitamin D activation, and stimulating renal conservation of calcium while increasing phosphate excretion.


MYTH: Coral calcium is recommended over other forms of calcium supplementation for preventing osteoporosis.


FACT: Coral calcium, which comes from limestone, isn't any better at preventing osteoporosis than other forms of calcium carbonate or calcium citrate.


MYTH: All osteoporosis medications slow bone resorption but don't affect bone formation.


FACT: PTH injections stimulate new bone formation, which helps strengthen bone and reduces fracture risk. The other osteoporosis medications work by slowing the rate of bone resorption so that it doesn't outpace bone formation. FDA-approved antiresorptive drugs include bisphosphonates (alendronate, ibandronate, and risedronate), calcitonin, hormone therapy, and the selective estrogen receptor modulator raloxifene.


MYTH: Unlike thin or normal-weight women, overweight women aren't at risk for osteoporosis.


FACT: After menopause, women produce their own natural estrogens in fat tissue, so being a little overweight may offer some protection against osteoporosis. However, overweight women still are at risk for osteoporosis. Also, the estrogen benefits of fat tissue are outweighed by the long-term health consequences of obesity.


Thin women (weighing less than 127 pounds [58 kg]) or those who have eating disorders that disrupt their menstrual cycles are at greater risk for osteoporosis. Maintaining a healthy, normal weight is best.


MYTH: Vitamin D3 (cholecalciferol) is better for bone health than vitamin D2 (ergocalciferol).


FACT: Although previous studies indicated that vitamin D3 was better, more recent studies haven't found a difference between the effect of the two forms of vitamin D on bone health.


Vitamin D helps with calcium absorption. Adults under age 50 need 400 to 800 international units of vitamin D daily; those 50 and older need 800 to 1,000 international units daily. This vitamin can be found in fortified milk, egg yolks, saltwater fish, liver, and supplements.


Source: National Osteoporosis Foundation.