Early puberty and more.

Health and medicine explained.
March 13 2007 7:22 AM

Your Health This Week

Early puberty, the problem with cold medicine, and the aftershocks of childhood cancer.

This week, Dr. Sydney Spiesel discusses the connection between fat and early puberty in girls, whether cold medicine is dangerous for babies, and the aftereffects of childhood cancer.

The role of fat in early puberty

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Question: There is ample evidence that children are, on average, becoming chunkier.  There is also ample evidence that girls are achieving puberty earlier than they used to. Is there a connection?

Background: Beginning in the early 1970s, Rose Frisch, an outstanding Harvard epidemiologist, observed that heavier girls matured earlier. There is a point before puberty at which girls usually begin to load on fat; Frisch hypothesized that this normal accumulation had to reach a critical point before menarche. The idea that good fat stores are a precondition for reproduction is biologically plausible: It takes about 50,000 calories above a woman's baseline metabolic needs to support a growing fetus over the course of a pregnancy. If women could become pregnant before they had the capacity to meet this need, it could be dangerous to the pregnancy. But does fat accumulation   trigger menarche, or is it the other way around, with the changes of puberty causing the accumulation of fat? It has been hard to definitively answer this question.

New study: Now, some new research by Joyce Lee and Julie Lumeng of the University of Michigan and their colleagues offers some clarity. They studied about 350 girls of diverse socioeconomic and geographic origins, all born in 1991. The girls' heaviness was estimated at 3 years of age and again at 4½ by calculating their body mass index percentile, an indirect measure of obesity, normal weight, or thinness. The girls were then tracked over time for evidence of the onset of puberty. As was expected from previous research, other factors like race, mother's age of puberty onset, and mother's education played a role in predicting when a girl would reach puberty. But none of these factors were nearly as important at predicting early puberty as a history of being overweight at age 3 or 4.

Next question: To my mind, this careful study establishes that the excess weight commonly seen in girls who reach puberty early is present long before the first signs of that development. What's still unknown is whether the weight itself sets off early puberty (indeed, we still have little understanding of the bodily events that trigger puberty) or whether some other event in the body leads to both the excess pounds in early childhood and to early maturation. Perhaps the connection has to do with leptin, a hormone manufactured by body fat. Leptin suppresses food intake by decreasing appetite, is known to bind to ovarian tissue, and has been used to restore menstruation to women whose periods have ceased because they are too thin.

Conclusion: Whatever the mechanism, the relationship between excess weight in childhood and early sexual maturation is worrisome. The increasing rate of childhood obesity may well lead to a general increase in some of the developmental problems we have come to associate with early puberty—including earlier initiation of alcohol use, earlier sexual debut (with its risk of early pregnancy and exposure to sexually transmitted diseases), and perhaps an increase in social and psychological problems. The stakes in the control of childhood obesity may turn out to be even higher than we thought.

Is cold medicine really unsafe for kids?

Question: Last week, the New York Times ran a front-page story about a CDC study that argued that over-the-counter cold remedies for children are probably useless and could be dangerous. It is easy for me to agree that most of those medicines don't do much—I've never seen any evidence in my patients that they're at all helpful, and here's my take on cough medicine. But dangerous? I'm not so sure.

New study: The CDC report, on three infant deaths in 2005 associated with the use of over-the-counter cold medications, is troublesome—and not what I would like to see as the basis for serious policy decisions. The authors searched the published literature and polled coroners and medical examiners in the United States and came up with only three infant deaths as a result of the use of cold medicine—all occurring in children under 6 months of age and all with sky-high blood levels of the active ingredient in over-the-counter remedies, pseudoephedrine. This suggests massive overtreatment by parents. Two of the three infants had pneumonia when they died, and the remaining infant had a multiplicity of risk factors that complicates understanding of the cause of death.

Caveat: Three deaths nationwide in one year, all in overdosed infants with medical problems—out of how many doses of over-the-counter cold medications given to infants overall? Let's see: There are about 4 million infants in their first year of life in the United States. We have no idea how many were given cold medications in the first year of life, but surely at least three-quarters, and many or them more than once? So we have three deaths in overdosed kids out of maybe 10 million or 20 million doses. In the same year, about 28,000 infants under the age of 1 died of all causes (here are three). The number of infants who died because of cold medicines may be higher than three, but relative to many other risks, it's hard to make a case that these medicines are very dangerous.

Conclusion: Still, why use these probably useless drugs in the first place? In my experience, most parents want desperately to relieve their suffering children, and television commercials work to assure us that relief is just a teaspoon away. Like most medications, the cold medicines are rarely tested in very young children, so we can't say for sure that they don't work (or of course that they do). And doctors often recognize that some parents need a tangible token of their caring, and figure that over-the-counter cold medicines are safer and better than the antibiotics parents often request. Ultimately, though, I like to keep in mind one of the most infallible laws of pediatrics: "If there's any illness for which there are a thousand treatments, none of them works."

The aftereffects of childhood cancer

Question: One of the great triumphs of modern medicine has been the development of successful cancer treatments. These days, more than 60 percent of adults who are treated for cancer survive for at least five years. Children do even better: Their five-year survival rate is between 80 percent and 85 percent. As a result, there are now about 270,000 survivors of childhood cancer. Which means that oncologists and other doctors are confronting the question of cancer's long-term health consequences. The present estimate is that about three-quarters of survivors of childhood cancer will have some ongoing health problem resulting from treatment. In about 40 percent, the aftereffects are likely to be severe.

New study: A recent review by Dr. Joseph Dickerman of the University of Vermont College of Medicine, as well as a report by Dr. Kevin Oeffinger and colleagues writing for the Childhood Cancer Survivor Study, found that the most common long-term effects involve the endocrine organs: In particular, decreased thyroid function after irradiation and damage to testicles or ovaries following radiation or some chemotherapy drugs. Other effects of cancer treatment include organ damage (heart problems, for instance), an increased risk of obesity, and an increased chance that a second cancer will occur.

Treatment: The thyroid problems can usually be treated with thyroid replacement medications. And to preserve future fertility in children being treated for cancer, doctors are using all kinds of tricks, including newer radiation methods, as well as sperm and ovarian tissue banking. Aftercare is probably best done by members of the child's oncology team because these doctors know best the exact treatment that led to survival and are likely to be most sensitive in detecting and averting future problems.

Also: I would add what I see as an underappreciated complication of cancer treatment—the psychological effects. The worry and disruption of normal life are sometimes invisible stressors, and during treatment the focus on medical intervention means that the psychological toll is often neglected. I think that the psychological effects are best addressed early on. Also, it's worth noting that some of the complications we are now seeing will become rare—and that new treatments will lead to new aftereffects.

Sydney Spiesel is a pediatrician in Woodbridge, Conn., and clinical professor of pediatrics at Yale University's School of Medicine.