Dear Doctor: I'm 71, and after a recent bone scan, my doctors are insisting I take a bone-building medication. I couldn't tolerate Fosamax, so they want me to take Prolia. I'm worried about it, but my mother had severe osteoporosis, so I'm worried about that too. How can I choose what to do?

Dear Reader: Your worry is well-founded. Osteoporosis is defined as a decrease of bone density greater than 2.5 standard deviations below the bone density of a healthy young adult, and it's more than three times more common in women than men. Women ages 65 to 80 have a 21 percent incidence of osteoporosis; those over 80 have a 35.6 percent incidence.

In addition, women fall more often than men, making bone loss especially dangerous. Three-quarters of all hip fractures occur in women. Not only are such fractures extremely disabling, requiring surgery and hospitalization, but also the overall one-year mortality after a hip fracture is 21.2 percent. Spine fractures are even more common than hip fractures in people with osteoporosis. Although they often go undiagnosed, they can cause debilitating pain.

So, obviously, if there is a way to improve your bone density and decrease your chance of fractures, you should do it.

Taking 500 to 1,000 milligrams of calcium a day and maintaining an adequate blood level of vitamin D are important, but to increase bone density, the first-line drug therapy is a bisphosphonate. These drugs, including Fosamax, increase bone mass and decrease the incidence of fractures. I would assume that you couldn't tolerate Fosamax due to irritation of the esophagus and stomach. If that's the case, you could consider injectable bisphosphonates such as Boniva or Reclast.

That said, all bisphosphonates can have rare, but potentially serious, side effects such as osteonecrosis of the jaw, an increased risk of fractures of the femur, and in the case of Reclast, atrial fibrillation. Also, note that people with kidney failure should not take bisphosphonates.

Prolia, given by injection twice a year, is different. It's a monoclonal antibody that binds specifically to a receptor within bone, inhibiting the normal bone breakdown. Clinical trials showed that, after three years of use, Prolia improved bone density in the spine by 9.2 percent and, after eight years, by 18.4 percent. It improved bone density in the hip by a lesser amount, 4 percent after three years and 8.3 percent after eight years. The drug was also linked to a 68 percent decrease in the rate of spinal fracture and a 40 percent decrease in the rate of hip fractures. In a trial comparing Prolia to Fosamax, those taking Prolia showed a slightly greater improvement in bone density after one year.

That's not to say Prolia is for everyone. Like Fosamax, it can occasionally lead to osteonecrosis of the jaw and atypical fractures. And, for people with kidney disease, it can lead to drops in calcium levels that can cause muscle spasms and abnormal heart rhythms. Finally, because Prolia is injected into the skin and may affect immune function, it may slightly increase the risk of skin infections at the site of the injection.

In summary, if you cannot tolerate Fosamax, you should consider injectable Reclast or Prolia. These medications do have rare, but severe, side effects. However, their benefits appear greater than their risks.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: What are the updated guidelines for cervical cancer screening? I'm 62 and want to know what is recommended going forward. Is an annual pelvic exam still necessary if a Pap smear isn't being done? And have guidelines changed for teens and 20-somethings?

Dear Reader: You've asked a lot of excellent questions that will have a broad spectrum of readers interested. And you're right, screening guidelines are changing.

A Pap test, also called a Pap smear, is used to screen for cervical cancer. It's a routine procedure that checks for cell changes on the cervix, which is the opening of the uterus. The test looks for abnormal cells that might become cervical cancer if not treated appropriately.

During a Pap smear, cells and mucus from the cervix are collected and then examined under a microscope. Cells from the same sample can also be used for an HPV test, to check for presence of the human papillomavirus, the most common sexually transmitted infection. Women with HPV have a higher risk of developing cervical cancer than women who do not have HPV.

Guidelines from the American Cancer Society as well as the American Congress of Obstetricians and Gynecologists recommend that all women should begin cervical cancer screening at age 21. Between 21 and 29, a Pap smear should be performed every three years. In this age group, HPV testing should only be used if a Pap smear returns with abnormal cell results.

When a woman turns 30, the Pap smear should be used along with an HPV test. This co-testing should continue at five-year intervals until age 65.

For women at higher risk of cervical cancer, screenings need to be performed more frequently. The most important risk factor for cervical cancer is the presence of human papillomavirus, which is actually a group of more than 150 related viruses. Certain types of HPV, sometimes referred to as high-risk, have been strongly linked to cervical cancer.

Additional risk factors for cervical cancer include smoking, having a weakened immune system due to HIV or taking immunosuppressive drugs, being infected with chlamydia, a family history of cervical cancer, and exposure to DES, a hormonal drug given to some women between 1940 and 1971. If any of these risk factors apply to you, talk to your physician or gynecologist about whether you should increase the frequency of screening.

At age 62, you're on track for at least one more round of co-testing with both a Pap smear and an HPV test. At age 65, the guidelines change again.

Women 65 and older who have had regular screenings for the previous 10 years, and whose tests have not turned up any abnormalities in the previous 20 years, can stop Pap smears.

As for pelvic exams, that's another nexus of change. The U.S. Preventive Services Task Force has recently declined to say that pelvic exams are necessary. Pelvic exams may have diagnostic value for detecting conditions like genital herpes, ovarian cysts, uterine fibroids, genital warts and others. We recommend that you discuss your options with your gynecologist or primary care physician.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: A friend suggested I try MSM crystals for arthritis. What are they, and do they work? If they do, where can I find them?

Dear Reader: Methylsulfonylmethane (MSM) is an organic sulfur-containing compound naturally found in plants such as Brussels sprouts, garlic, asparagus, kale, beans and wheat germ. It can also be found in horsetail, an herbal remedy. MSM, which has been touted as a treatment for arthritis, is related to a similar compound, dimethyl sulfoxide (DMSO), that has been shown to have anti-inflammatory properties. MSM may have anti-inflammatory properties as well, but different from those associated with aspirin or nonsteroidal anti-inflammatory agents (NSAIDs). Unlike DMSO, which is a liquid applied at room temperature, MSM is a white crystalline compound -- hence the reference to "crystals."

As for whether it works, let's look at the evidence. A 2011 study performed in Israel assessed its impact on 50 people with arthritis of the knee. Twenty-five patients took a placebo, while 25 took 1.125 grams of MSM three times per day for 12 weeks. At 12 weeks, symptoms had worsened by 14 percent in the placebo group, but had improved by 20 percent in the MSM group. Pain had increased by 9 percent in the placebo group, but had decreased by 21 percent in the MSM group. Note that in this 12-week study, users noted no side effects.

A 2006 study also assessed MSM's impact on people with arthritis of the knee, with 25 people receiving a placebo and the other 25 receiving a 3-gram dose of MSM twice a day. At 12 weeks, pain had decreased by 25 percent in the MSM group, and by 13 percent in the placebo group. The physical function of the knee also improved with the use of MSM, but stiffness improved only slightly as compared to the placebo. This higher dose of MSM was associated with the mild side effects of bloating and constipation. One interesting note: The study authors found no change in inflammatory markers with MSM.

Lastly, a 2004 study from India compared the use of MSM, the use of glucosamine, the use of a combination and the use of a placebo for arthritis of the knee. After 12 weeks, patients who took 500 milligrams of MSM three times a day reported a significant reduction in pain and swelling of the knee. This was also seen in the group who took glucosamine. Those who took the combination of both MSM and glucosamine reported an additive benefit in regard to pain and swelling.

Granted, these are small studies, but they do show a slight benefit from MSM, but even milder than from Tylenol or NSAIDs. In these studies, the medication was used every day for 12 weeks, so I would assume that you would have to take MSM daily for a long period to see the benefit.

One important caveat: We don't know if there are any long-term side effects with MSM. If you do try it, start with 500 to 1,000 milligrams three times per day. That dose can be found in any drug or vitamin store.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)