Update From the Medical Journals: December 2010
December 31, 2010
By Mary Pickett, M.D.
What's the latest news in the medical journals this month? Find out what your doctor is reading.
An Institute of Medicine (IOM) panel has made new recommendations about how much vitamin D is best for health. The panel brings together independent scientists who advise the government on health issues. It's been 13 years since the guidelines were last updated.
Although most people are getting adequate vitamin D, the IOM panel stated that children, adolescent girls and many adults need supplements to meet the guidelines. The panel recommended increasing the "recommended daily allowance" (RDA), the amount we should get from food and supplements each day. The IOM published its report on November 30.
The new RDAs are based on age:
People with a vitamin-D deficiency need higher-dose supplements.
The IOM also recommended new daily amounts for calcium:
Vitamin D has become a hot topic among health experts in recent years. Vitamin D is important for bone strength and muscle health. Low vitamin D causes muscle weakness, muscle aches and a higher risk for falling. Having a normal level of vitamin D helps to prevent infections and cancer. A recent study also showed that people who have vitamin D levels below 15 ng/mL (nanograms per milliliter) appear to have about twice the risk of having a heart or stroke, compared with people who have higher levels.
The report cautioned that we don't know how safe it is to take doses of vitamin D that exceed the RDA if you don't have a known deficiency. The report also advises that people who take supplements should not go overboard on their dosing. Too much vitamin D can definitely lead to health problems, such as kidney stones or high calcium levels. Very high calcium levels can cause abdominal symptoms and confusion.
Ovarian cancer is one of the most challenging cancers to treat. It can occur at a young age, compared to other cancers. About three out of four ovarian cancer cases are not found until the disease is in a later stage. What would happen if we asked women to have yearly screening tests for ovarian cancer? Would this help us identify ovarian cancer much earlier than we can now? If so, maybe more women could survive this cancer.
A new study reviewed the currently available screening tests for ovarian cancer, and predicted whether these tests could prevent deaths cancer if they were repeated on a yearly basis. The study found that the available tests are almost useless against this cancer.
The study was published online by the journal Cancer on December 13.
The two screening tests this study looked at are ultrasound and the CA-125 blood test. (High levels of the CA-125 protein can sometimes be a sign of cancer, including ovarian cancer. But the test is not very specific.)
Researchers created a computer model to show the growth of ovarian cancer. Some types grow faster and others more slowly, and the model accounted for this difference. Researchers estimated how many cancers could be detected with current screening tests, and at what stages. Researchers found that yearly screening tests are more likely to detect slow-growing cancers than fast-growing ones. Overall, having screening tests every year would only reduce deaths from ovarian cancer by about 11%. This is too small a number to make the cost of testing worthwhile for women at average risk.
Women who have a family history of ovarian cancer or who carry a BRCA gene are at high risk for ovarian cancer. The most effective way to protect yourself against ovarian cancer, in this situation, is to have the ovaries surgically removed. The long-term use of birth control pills can cut the risk for this cancer in half. Having a tubal ligation (having your "tubes tied") also seems to lower the risk for ovarian cancer.
Daily use of two drugs that treat HIV can help prevent infection in people who practice risky sex, according to a new study. The study was published online by the New England Journal of Medicine November 23.
Regular condom use has been the preferred way to prevent the spread of HIV infection. But researchers decided to take a serious look at preventing infection with drugs. In the past, the cost of the medicines and side effects have discouraged experts from testing this approach as a way to prevent infection.
The study included nearly 2,500 men and transgender women who had sex with men. These participants were chosen because they were at high risk for HIV exposure. Many of the participants had risky drinking habits, traded sex for money, or reported frequent sex without condoms. Many of the participants had more than 1 sexual partner each week; more than 80% had unprotected sex in the last 6 months. At the start of the study, none of the participants were infected with HIV.
The people in the study were randomly divided into 2 groups of similar size. The participants in one group took the HIV combination treatment pill "Truvada" daily. (Truvada includes the HIV drugs emtricitabine and tenofovir.) The other group took a placebo pill. All of the participants received counseling and condoms. (They were advised to use condoms every time they had sex). The study lasted for almost 3 years. During that time, 64 men taking placebo pills and 36 men taking Truvada became infected.
Among those who took their pills at least half the time, the risk of getting HIV was cut in half. For those who took almost all of their medicine (90% of what was prescribed), the risk dropped by 73%.
For people who engage in risky sex, taking HIV medicine as a way to prevent HIV infection might be a reasonable addition to current prevention strategies. Long-term safety and cost issues still need to be worked out.
Mary Pickett, M.D. is an Associate professor at Oregon Health & Science University where she is a primary care doctor for adults. She supervises and educates residents in the field of Internal Medicine, for outpatient and hospital care. She is a Lecturer for Harvard Medical School and a Senior Medical Editor for Harvard Health Publications.