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Each year, more than 4.5 million dog bites occur in the United States. Despite what you might assume, most of these incidents don’t happen when an unfamiliar dog attacks someone in a park or another outdoor location. Instead, most dog bites are inflicted by a pet dog in a home.

Here’s advice for avoiding these upsetting and potentially serious injuries — and the steps you should take if you sustain a dog bite.

Why do dog bites happen?

Some dog bites happen by accident when people wrestle or play tug-of-war with their dog. But most of the time, dogs bite people as a reaction to feeling stressed, threatened, scared, or startled, according to the American Veterinary Medical Association (AVMA). More than half of dog bites occur in children, and they’re far more likely to be seriously injured than adults.

“People don’t always heed the behavioral signals that a dog is uncomfortable,” says Dr. Christopher Baugh, associate professor of emergency medicine at Harvard Medical School. For example, some dogs are highly territorial and will bark, growl, snap, and lunge if outsiders enter their space — whether that’s an apartment, yard, or crate. Or dogs may exhibit resource guarding, which shows up as anxious, aggressive behavior around food, toys, or beds.

“These situations can be high-risk, and children in particular have less awareness of that risk,” says Dr. Baugh, who has children and two mixed-breed rescue dogs, Harley and Roxi.

What can you do to prevent dog bites?

Any dog — even a sweet, cuddly dog — can bite if provoked, according to the AVMA. Never leave young children alone with a dog without adult supervision. And teach children to never disturb a dog while it’s eating, sleeping, or caring for puppies.

In a study of 321 facial dog bites treated at Harvard-affiliated Massachusetts General Hospital over a 20-year period, 88% of the bites were from known dogs. Most were in adults and occurred after playing with the dog, feeding the dog, and placing their face close to the dog. However, the hand (usually a person’s dominant hand) is probably the most common location for a dog bite in an adult, says Dr. Baugh.

Other tips from the CDC to prevent dog bites include the following:

• Always ask a dog’s owner if it’s okay to pet their dog, even if the dog appears friendly.
• Make sure the dog sees and sniffs you before reaching out to pet it.
• Don’t pet a dog that seems to be hiding, scared, sick, or angry.

What if an unfamiliar dog approaches you? Remain calm and still, avoiding eye contact with the dog. Stand with the side of your body facing the dog and say “no” or “go home” in firm, deep voice. Wait for the dog to retreat or move yourself slowly away.

What should you do if you’re bitten by a dog?

Clean the wound with mild soap and running water, then cover it with a clean bandage or cloth. Some online resources recommend applying an antibiotic ointment or cream. But these products are recommended only for people with clear evidence of an infection, such as redness, pus, pain, swelling, or warmth, according to the American Academy of Dermatology.

If the injury is serious — with a bite on the face, heavy bleeding, or a possible broken bone — go to the emergency room. That’s also a good idea if you’re bitten by an unknown or stray dog, in the rare event that you might need medicines to prevent rabies (rabies post-exposure prophylaxis).

“Often, people are shocked after being bit and will understandably focus all their attention on their wound,” says Dr. Baugh. The dog’s owner may check in to see if you’re okay, but then walk away. But you should get the person’s contact information and make sure the dog is vaccinated against rabies, he says.

Keep in mind that:

• Emergency rooms are often crowded with long waits, so an urgent care clinic is a good option if the injury doesn’t require immediate attention.
• Some wounds require stitches, ideally within 12 to 24 hours.
• The doctor may prescribe antibiotics to prevent possible infections, especially if you have health problems such as a weakened immune system or diabetes.
• You may also need a tetanus booster if you haven’t had one in the past 10 years. If your vaccine history isn’t available or you can’t remember, you’ll get a tetanus booster just in case.

What if a dog bite is less serious?

Let’s say you have a less serious bite from a family dog known to have a current rabies vaccine. Bites that don’t require stitches can be cleaned with mild soap and running water, then evaluated by your regular health care provider. They may tell you to simply monitor the wound for signs of infection.

“Doctors are trying to be more thoughtful about prescribing antibiotics and limit their use in low-risk situations, because overuse contributes to antibiotic resistance and exposes people to potential side effects without any benefit,” says Dr. Baugh.

About the Author

Julie Corliss, Executive Editor, Harvard Heart Letter

Julie Corliss is the executive editor of the Harvard Heart Letter. Before working at Harvard, she was a medical writer and editor at HealthNews, a consumer newsletter affiliated with The New England Journal of Medicine. She … See Full Bio View all posts by Julie Corliss

About the Reviewer

Howard E. LeWine, MD, Chief Medical Editor, Harvard Health Publishing

Dr. Howard LeWine is a practicing internist at Brigham and Women’s Hospital in Boston, Chief Medical Editor at Harvard Health Publishing, and editor in chief of Harvard Men’s Health Watch. See Full Bio View all posts by Howard E. LeWine, MD

If the eyes are the windows to the soul, then consider the tongue a sort of check-engine light for the body. The tongue’s appearance gives doctors an idea about certain aspects of your health, and its color is an important clue.

What should your tongue look like?

The tongue should have a rounded, symmetrical shape. It’s generally light pink, though it may have a little purple or brown pigmentation in African, Asian, and Mediterranean populations. It can also have a hint of white coating.

“The coating comes from a tough protein called keratin, which helps keep your tongue from being scratched when you eat,” says Dr. Tien Jiang, a prosthodontist in the Department of Oral Health Policy and Epidemiology at the Harvard School of Dental Medicine.

Up close, you might be able to see that your tongue is covered in tiny bumps (papillae) that serve several purposes:

• They sense temperature and touch.
• They contain taste buds that enable you to detect if food is sweet, salty, sour, bitter, or savory.
• They create friction to help you form a little ball of food (bolus) that you can swallow.

Can diet affect tongue color?

Yes. Sometimes diet may be partly to blame for a shift away from your usual tongue tone. That’s because the papillae can absorb the colors and residues of foods and drinks you consume. For example, that blue popsicle or candy you ate as a kid probably turned your tongue an exciting shade of azure. Coffee, tea, and many types of foods, such as curried dishes with lots of yellow turmeric, can also leave their marks.

Discoloration is usually just temporary, however. Drinking plenty of water and maintaining good oral hygiene will wash away food and dyes that cling to the tongue.

A dark or bright tongue, white patches, and other causes for concern

Some tongue colors and appearances are signs of health issues. Check with your doctor if you notice any of the following:

• A brown or black tongue signals a condition called “black hairy tongue.” This occurs when papillae get too long. These tiny bumps don’t usually get much chance to grow because they are shed regularly with all the activity in your mouth. If they do grow, they can trap bacteria and a mix of food colors, leading to the brown or black tinge. Risk factors include taking antibiotics or antihistamines, smoking, dry mouth, drinking excessive amounts of coffee or black tea, or poor oral hygiene.
• Thick white patches or white sores on the tongue probably mean you have an overgrowth of yeast in the mouth (thrush). Thrush can be triggered by conditions such as diabetes or HIV, side effects of antibiotics or cancer treatment, wearing dentures, smoking, dry mouth, or using steroid inhalers. In rare cases, white patches or sores are symptoms of oral cancer.
• If your tongue has painful red or yellow sores, you might be dealing with canker sores (irritated tissues), thrush (which can sometimes appear as red patches), or (in rare cases) oral cancer.
• A bright red tongue can indicate that you have a vitamin B12 deficiency or an infection called scarlet fever — a Streptococcus bacteria infection in the throat (strep throat) accompanied by a red body rash. If you have bright red patches that don’t hurt and seem to migrate from one place on the tongue to another, you might have a harmless, incurable condition called “geographic tongue.”

Should you brush your tongue or use a tongue scraper?

Good oral hygiene requires that you floss your teeth at least once a day and brush them at least twice a day. Take a few seconds to use the brush on your tongue.

“Stick out your tongue and swipe your toothbrush from the back of your tongue to the front: one swipe down the middle, one swipe down the left side, and one swipe down the right side. That helps remove bacteria and debris that collect in papillae,” Dr. Jiang says.

Some people swear by using a tongue scraper to clean the tongue. Dr. Jiang isn’t a fan, but doesn’t have a problem with someone using the tool, which is pulled forward on the tongue in a similar fashion to brushing the tongue. “The data about tongue scraper effectiveness are mixed,” she says. “It just comes down to what you’re willing to do daily to keep your tongue, teeth, mouth, and gums as healthy as possible.”

Worried about your tongue? What to do

If you’re worried about anything wrong with your tongue — especially if you also have a fever, a very sore throat, sores that won’t go away, or other new symptoms — call your primary care doctor or dentist.

Your doctor or dentist can

• assess your condition
• prescribe or suggest treatments to relieve discomfort, such as medicated mouthwashes or warm-water rinses
• urge you to stay hydrated and step up your oral hygiene.

If necessary, your doctor can refer you to a specialist for further evaluation.

About the Author

Heidi Godman, Executive Editor, Harvard Health Letter

Heidi Godman is the executive editor of the Harvard Health Letter. Before coming to the Health Letter, she was an award-winning television news anchor and medical reporter for 25 years. Heidi was named a journalism fellow … See Full Bio View all posts by Heidi Godman

About the Reviewer

Howard E. LeWine, MD, Chief Medical Editor, Harvard Health Publishing

Dr. Howard LeWine is a practicing internist at Brigham and Women’s Hospital in Boston, Chief Medical Editor at Harvard Health Publishing, and editor in chief of Harvard Men’s Health Watch. See Full Bio View all posts by Howard E. LeWine, MD

Trees enhance life in a multitude of ways. They combat climate change by reducing greenhouse gases in the atmosphere. They muffle sound pollution and reduce air pollution, drawing in carbon dioxide and releasing oxygen. When rain pours from the skies, trees decrease stormwater runoff, preventing flooding and soil erosion. They also provide valuable habitats to support biodiversity in insects, birds, and other animals, and microorganisms. The list goes on.

Equally important is accumulating evidence that simply spending time around trees and green spaces uplifts our health and mood. Below are a few of the biggest benefits we reap.

Keeping it cool: Trees help prevent heat-related illness

Climate change is causing rising temperatures and more heat waves across the US. These effects are worse for those who live in neighborhoods known as urban heat islands, where asphalt and concrete soak up heat during the day and continue to radiate it at night. Temperatures can reach 7° F hotter than suburban, rural, or simply wealthier and leafier neighborhoods.

Trees and their leafy canopy provide shade that helps to prevent urban heat islands. What does that mean for individuals? It translates to fewer heat-related health illnesses, which strike outdoor workers and younger, older, and medically vulnerable people more often. A study published in The Lancet calculated that increasing tree canopy to 30% coverage in 93 European cities could prevent an estimated four in 10 premature heat-related deaths in adults in those cities.

How trees help children: Better mood, behavior, attention, and more

Spending more time in nature has been linked with better health outcomes like lower blood pressure, better sleep, and improvement in many chronic conditions in adults. These findings are prompting a growing interest in forest therapy, a guided outdoor healing practice that leads to overall improved well-being. But what’s also remarkable are the varied benefits of trees and nature for children.

One study of children 4 to 6 years old found that those who lived close to green space demonstrated less hyperactive behavior and scored more highly on attention and visual memory testing measures compared with children who did not.

Just seeing trees can have mental health benefits. In Michigan, a study of children between the ages of 7 and 9 demonstrated that students who could see trees from their school windows had fewer behavioral problems than those with limited views.

In Finland, researchers modified daycare outdoor playscape environments to mimic the forest undergrowth. These daycares were compared to control standard daycares and nature-oriented daycares where children made daily visits to nearby forests. At the end of 28 days, the children in the daycares with modified forest undergrowth playscapes harbored a healthier microbiome and had improved markers of their immune systems as compared to their counterparts.

How green space helps communities

Having green space in neighborhoods also does a lot to enrich the well-being of communities. A randomized trial in a US city planted and maintained grass and trees in previously vacant lots. Researchers then compared these green spaces to lots that were left alone.

In neighborhoods below the poverty line, there was a reduction in crime for areas with greened lots compared to untouched vacant lots. Meanwhile, residents who lived near lots that were greened reported feeling safer and increased their use of the outside space for relaxing and socializing.

How can you help?

Unfortunately, urban tree canopy cover has been declining over the years. To counter this decline, many towns and nonprofit organizations have programs that provide trees for planting.

A few examples in Massachusetts are Canopy Crew in Cambridge and Speak for the Trees in Boston. (Speak for the Trees also offers helpful information on selecting and caring for trees). Neighborhood Forest provides trees for schools and other youth organizations across the US. Look for a program near you!

Planting trees native to your region will better suit the local conditions, wildlife, and ecosystem. Contact your regional Native Plant Society for more information and guidance. If you are worried about seasonal allergies from tree pollen, many tree organizations or certified arborists can give you guidance on the best native tree selections.

If planting trees is not for you but you are interested in contributing to the mission, consider donating to organizations that support reforestation, like The Canopy Project and the Arbor Day Foundation.

About the Author

Wynne Armand, MD, Contributor

Dr. Wynne Armand is a physician at Massachusetts General Hospital (MGH), where she provides primary care; an assistant professor in medicine at Harvard Medical School; and associate director of the MGH Center for the Environment and … See Full Bio View all posts by Wynne Armand, MD

Colon cancer is the second-deadliest form of cancer after lung cancer. If recent messages about colon cancer screening have left you a little confused, that's understandable. In August, the American College of Physicians (ACP) released updated guidance for colon cancer screening that differs from other major organizations, including recommendations from the American Cancer Society (ACS) and the US Preventive Services Task force (USPSTF).

So, what do you need to know?

How does the advice differ?

First, please note that this advice applies only to people at average risk without a family history of colon cancer. If you have family history, or if other health issues put you at higher-than-average risk for colorectal cancer, talk to your doctor about the best course of action for you.

The main point of disagreement relates to the age at which people should start getting screened. The new ACP guidance says 50, while the other two organizations recommend 45. That earlier age is endorsed by the U.S. Multisociety Task Force on Colorectal Cancer. It's also endorsed by many physicians, including Harvard Medical School professor Dr. Andrew T. Chan, a gastroenterologist and director of epidemiology at Massachusetts General Hospital Cancer Center, who helps explain key facts below.

Why do experts suggest starting screening earlier?

"We're facing an unexplained and alarming increase in the incidence of colon cancer in people younger than 50," says Dr. Chan.

Overall, deaths from colon cancer dropped by 2% per year from 2011 to 2020. But that's not the case among people younger than 50. In that age group, deaths from colon cancer rose between 0.5% and 3% during the same time period, according to statistics published in 2023.

The rising rates of colon cancer in younger people are occurring in all racial and ethnic groups, with the steepest rises seen among Alaskan Natives and Native Americans. Overall, Blacks and African Americans are more likely to get and die from colon cancer than whites, and early-onset cases are higher in Black individuals than whites.

Efforts to encourage colon cancer screening began in the mid-1990s. Today, about 60% of adults over 50 follow the advice to receive a colonoscopy (described below) on a regular basis. This track record, while not perfect, likely explains the decline in deaths from colon cancer in older adults.

"I think that promoting earlier screening will help stem the rise in early-onset cases, at least for those in their 40s. We've also seen that earlier colonoscopies may be associated with lowering incidence of colon cancer even later in life, "says Dr. Chan.

What are the different screening tests for colon cancer?

The two most widely used screening tests are a standard colonoscopy and various stool-based tests.

Colonoscopy. For this test, a gastroenterologist or surgeon snakes a long, flexible tube with a camera on the end through your rectum and beyond to inspect the entire length of your colon. Considered the gold-standard test, this procedure can detect precancerous polyps called adenomas, and allow for their removal.

The test requires taking laxatives and drinking lots of fluids beforehand to clean all the fecal material (stool) out of your colon. Serious complications, which include perforation or bleeding, are rare, occurring in about three in 1,000 procedures. If no polyps are found, a repeat colonoscopy isn't recommended for another 10 years. If you have polyps, or your risk or symptoms change, this interval will be shorter.

Stool tests. The more worrisome colon polyps (adenomas) often shed tiny amounts of blood and abnormal DNA into the stool. This can be detected from samples you collect yourself at home.

• Two tests, the fecal occult blood test (FOBT) and fecal immunochemical test (FIT), check for blood. They require small stool samples that you put on a card or in a tube that's then mailed to a lab. These tests should be done every year.
• A third option, the FIT-DNA test, checks for both blood and abnormal DNA; it's usually repeated every three years.

Additionally, the guidelines from the American College of Physicians suggest another option: flexible sigmoidoscopy, which inspects only the lower part of the colon, once every 10 years, combined with a fecal FIT testing every two years. However, doctors in the United States rarely order sigmoidoscopy today.

If flexible sigmoidoscopy or any of these stool tests show evidence of a problem, a colonoscopy is needed to check for adenomas or cancer.

Why might stool-based screening make sense for younger adults?

Colonoscopy isn't necessarily the best initial screening test for everyone, says Dr. Chan. That's especially true for younger people, mainly because it's time-consuming and inconvenient.

"Maybe you just can't find time in your schedule or are worried about having a colonoscopy," he says. If that's the case, a stool-based test — which is noninvasive and takes very little time — is an appropriate option.

"The worst option is not doing anything, because early detection and treatment can prevent deaths," he says.

About the Author

Julie Corliss, Executive Editor, Harvard Heart Letter

Julie Corliss is the executive editor of the Harvard Heart Letter. Before working at Harvard, she was a medical writer and editor at HealthNews, a consumer newsletter affiliated with The New England Journal of Medicine. She … See Full Bio View all posts by Julie Corliss

About the Reviewer

Howard E. LeWine, MD, Chief Medical Editor, Harvard Health Publishing

Dr. Howard LeWine is a practicing internist at Brigham and Women’s Hospital in Boston, Chief Medical Editor at Harvard Health Publishing, and editor in chief of Harvard Men’s Health Watch. See Full Bio View all posts by Howard E. LeWine, MD

By the time boys are 8 or 10, they’re steeped in Marvel action heroes with bulging, oversized muscles and rock-hard abs. By adolescence, they’re deluged with social media streams of bulked-up male bodies.

The underlying messages about power and worth prompt many boys to worry and wonder about how to measure up. Sometimes, negative thoughts and concerns even interfere with daily life, a mental health issue known body dysmorphic disorder, or body dysmorphia. The most common form of this in boys is muscle dysmorphia.

What is muscle dysmorphia?

Muscle dysmorphia is marked by preoccupation with a muscular and lean physique. While the more extreme behaviors that define this disorder appear only in a small percentage of boys and young men, it may color the mindset of many more.

Nearly a quarter of boys and young men engage in some type of muscle-building behaviors. “About 60% of young boys in the United States mention changing their diet to become more muscular,” says Dr. Gabriela Vargas, director of the Young Men’s Health website at Boston Children’s Hospital. “While that may not meet the diagnostic criteria of muscle dysmorphia disorder, it’s impacting a lot of young men.”

“There’s a social norm that equates muscularity with masculinity,” Dr. Vargas adds. “Even Halloween costumes for 4- and 5-year-old boys now have padding for six-pack abs. There’s constant messaging that this is what their bodies should look like.”

Does body dysmorphic disorder differ in boys and girls?

Long believed to be the domain of girls, body dysmorphia can take the form of eating disorders such as anorexia or bulimia. Technically, muscle dysmorphia is not an eating disorder. But it is far more pervasive in males — and insidious.

“The common notion is that body dysmorphia just affects girls and isn’t a male issue,” Dr. Vargas says. “Because of that, these unhealthy behaviors in boys often go overlooked.”

What are the signs of body dysmorphia in boys?

Parents may have a tough time discerning whether their son is merely being a teen or veering into dangerous territory. Dr. Vargas advises parents to look for these red flags:

• Marked change in physical routines, such as going from working out once a day to spending hours working out every day.
• Following regimented workouts or meals, including limiting the foods they’re eating or concentrating heavily on high-protein options.
• Disrupting normal activities, such as spending time with friends, to work out instead.
• Obsessively taking photos of their muscles or abdomen to track “improvement.”
• Weighing himself multiple times a day.
• Dressing to highlight a more muscular physique, or wearing baggier clothes to hide their physique because they don’t think it’s good enough.

“Nearly everyone has been on a diet,” Dr. Vargas says. “The difference with this is persistence — they don’t just try it for a week and then decide it’s not for them. These boys are doing this for weeks to months, and they’re not flexible in changing their behaviors.”

What are the health dangers of muscle dysmorphia in boys?

Extreme behaviors can pose physical and mental health risks.

For example, unregulated protein powders and supplements boys turn to in hopes of quickly bulking up muscles may be adulterated with stimulants or even anabolic steroids. “With that comes an increased risk of stroke, heart palpitations, high blood pressure, and liver injury,” notes Dr. Vargas.

Some boys also attempt to gain muscle through a “bulk and cut” regimen, with periods of rapid weight gain followed by periods of extreme calorie limitation. This can affect long-term muscle and bone development and lead to irregular heartbeat and lower testosterone levels.

“Even in a best-case scenario, eating too much protein can lead to a lot of intestinal distress, such as diarrhea, or to kidney injury, since our kidneys are not meant to filter out excessive amounts of protein,” Dr. Vargas says.

The psychological fallout can also be dramatic. Depression and suicidal thoughts are more common in people who are malnourished, which may occur when boys drastically cut calories or neglect entire food groups. Additionally, as they try to achieve unrealistic ideals, they may constantly feel like they’re not good enough.

How can parents encourage a healthy body image in boys?

These tips can help:

• Gather for family meals. Schedules can be tricky. Yet considerable research shows physical and mental health benefits flow from sitting down together for meals, including a greater likelihood of children being an appropriate weight for their body type.
• Don’t comment on body shape or size. “It’s a lot easier said than done, but this means your own body, your child’s, or others in the community,” says Dr. Vargas.
• Frame nutrition and exercise as meaningful for health. When you talk with your son about what you eat or your exercise routine, don’t tie hoped-for results to body shape or size.
• Communicate openly. “If your son says he wants to exercise more or increase his protein intake, ask why — for his overall health, or a specific body ideal?”
• Don’t buy protein supplements. It’s harder for boys to obtain them when parents won’t allow them in the house. “One alternative is to talk with your son’s primary care doctor or a dietitian, who can be a great resource on how to get protein through regular foods,” Dr. Vargas says.

About the Author

Maureen Salamon, Executive Editor, Harvard Women's Health Watch

Maureen Salamon is executive editor of Harvard Women’s Health Watch. She began her career as a newspaper reporter and later covered health and medicine for a wide variety of websites, magazines, and hospitals. Her work has … See Full Bio View all posts by Maureen Salamon

About the Reviewer

Howard E. LeWine, MD, Chief Medical Editor, Harvard Health Publishing

Dr. Howard LeWine is a practicing internist at Brigham and Women’s Hospital in Boston, Chief Medical Editor at Harvard Health Publishing, and editor in chief of Harvard Men’s Health Watch. See Full Bio View all posts by Howard E. LeWine, MD

You probably know that you have a thyroid gland. Perhaps you or someone you know has had thyroid tests or a thyroid disorder such as hypothyroidism.

But did you know you also have a parathyroid gland? It’s true — in fact, most people have four of them, even though one would suffice.

Where are the parathyroid glands?

From the name, you might assume the role of the parathyroid glands is related to that of the thyroid gland. Well, you’d be wrong. The name comes solely from their location: they sit just behind the thyroid gland: two on the right side, two on the left.

The parathyroid glands are small (the size of peas), and can weigh less than a thousandth of an ounce each. Although it’s normal to have four parathyroid glands, about 13% of people have fewer and 5% have more. And some people have parathyroid glands in other locations, such as alongside the esophagus or in the chest. This variation rarely matters, unless surgery is necessary to remove one or more of them.

What do the parathyroid glands do?

Logically enough, parathyroid glands make parathyroid hormone (PTH). And what does PTH do? It has several functions, including:

• Regulating calcium: Calcium is a mineral with many essential roles throughout the body, such as maintaining bone strength, allowing nerves and muscles to function normally, and making sure blood clots as it should. Higher levels of PTH lead to higher calcium levels in the blood through actions on the kidneys and bones.
• Regulating phosphorus: Among other roles, this mineral is a key component of our DNA, bones, and teeth. Phosphorus activates essential enzymes throughout the body, including enzymes necessary for cell reproduction and survival. It also helps with nerve and muscle function.
• Regulating vitamin D: This vitamin is actually a hormone that helps maintain normal levels of calcium throughout the body, by controlling how much gets absorbed from food in the intestinal tract and how much is lost by the kidneys in your urine. Remember PTH? Well, PTH regulates production of the enzyme that converts inactive vitamin D to an active form that helps your gut absorb calcium and reduces the loss of calcium in urine.

PTH released by the parathyroid glands helps keep each of these nutrients in balance. For example, if your blood calcium level falls, your parathyroid glands make more PTH. Higher amounts of PTH prompt bones to release stored calcium into the bloodstream, and also signal the kidneys to pull back on the amount of calcium lost through urine.

What if your blood calcium level rises? Then the parathyroid glands make less PTH, which helps to correct the blood calcium level.

Which diseases involve the parathyroid glands?

The most common are:

• Hyperparathyroidism: This is a condition in which the parathyroid glands make more than the normal amount of PTH. This can be due to a benign or cancerous tumor on a single gland, or due to multiple glands becoming overactive. Or it may be due to some other trigger, such as a low level of calcium in the blood, inadequate vitamin D levels, or kidney failure. When there’s too much PTH, blood calcium levels can become dangerously high and phosphorus levels fall. Surgery may be recommended to remove the overactive gland or glands.
• Hypoparathyroidism: This rare condition is diagnosed when less than the normal amount of PTH is produced. The most common causes are prior neck surgery or radiation, autoimmune disease, or low magnesium levels.
• Parathyroid cancer: Risk factors for parathyroid cancer include certain genetic diseases and prior radiation to the neck.

Why do we rarely hear about the parathyroid glands?

The reason is that most of the time they do their job without fuss or fanfare. Although disorders of the parathyroid glands are not rare, they are just uncommon enough that most people will never hear about them. I think of the parathyroid glands as one of many parts of our bodies that play a huge role in our health, but go unappreciated because they are so good at what they do.

Many other quiet heroes, including the thymus gland, serve as testaments to the remarkable design and function of the human body. Then again, I can think of a few body parts that could be considered expendable.

The bottom line

I hope it’s comforting to know that your amazing parathyroid glands are keeping tabs on your calcium levels and helping your bones, nerves, muscles, and other organs to function normally.

Ounce for ounce, the parathyroid glands may be the most important glands you’d never heard of. Until now.

About the Author

Robert H. Shmerling, MD, Senior Faculty Editor, Harvard Health Publishing; Editorial Advisory Board Member, Harvard Health Publishing

Dr. Robert H. Shmerling is the former clinical chief of the division of rheumatology at Beth Israel Deaconess Medical Center (BIDMC), and is a current member of the corresponding faculty in medicine at Harvard Medical School. … See Full Bio View all posts by Robert H. Shmerling, MD

Want your child to grow up healthy, happy, smart, capable, and resilient? Play with them. Infants and toddlers thrive on playful games that change as they grow.

Why does play matter during the first few years of life?

More than a million new nerve connections are made in the brain in the first few years of life. And pruning of these neural connections makes them more efficient. These processes literally build the brain and help guide how it functions for the rest of that child’s life. While biology — particularly genetics — affects this, so does a child’s environment and experiences.

Babies and children thrive with responsive caregiving. Serve and return, a term used by the Harvard Center on the Developing Child, describes this well: back-and-forth interactions, in which the child and caregiver react to and interact with each other in a loving, nurturing way, are the building blocks of a healthy brain and a happy child, who will have a better chance of growing into a healthy, happy, competent, and successful adult.

Play is one of the best ways to do responsive caregiving. To maximize the benefits of play:

• Bring your full attention. Put the phone down, don’t multitask.
• Be reciprocal. That’s the “serve and return” part. Even little babies can interact with their caregivers, and that’s what you want to encourage. It doesn’t have to be reciprocal in an equal way — you might be talking in sentences while your baby is just smiling or cooing — but the idea is to build responsiveness into the play.
• Be attuned to developmental stages. That way your child can fully engage — and you can encourage their development as well.

Great games to play with infants: 6 to 9 months

The Center for the Developing Child has some great ideas and handouts for parents about specific games to play with their children at different ages.

6-month-olds and 9-month-olds are learning imitation and other building blocks of language. They are also starting to learn movement and explore the world around them.

Here are some play ideas for this age group:

• Play peek-a-boo or patty-cake.
• Play games of hiding toys under a blanket or another toy, and then “find” them, or let the baby find them.
• Have back-and-forth conversations. The baby’s contribution might just be a “ma” or “ba” sound. You can make the same sound back, or pretend that your baby is saying something (“You don’t say! Really? Tell me more!”).
• Play imitation games: if your baby sticks out their tongue, you do it too, for example. Older babies will start to be able to imitate things like clapping or banging, and love when grownups do that with them.
• Sing songs that involve movement, like “Itsy Bitsy Spider” or “Trot, Trot to Boston” with words and motions.
• Play simple games with objects, like putting toys into a bucket and taking them out, or dropping them and saying “boom!”

Great games to play with toddlers

Between 12 months and 18 months, young toddlers are gaining more language and movement skills, and love to imitate. You can:

• Play with blocks, building simple things and knocking them down together.
• Do imaginative play with dolls or stuffed animals, or pretend phone calls.
• Use pillows and blankets to build little forts and places to climb and play.
• Play some rudimentary hide-and-seek, like hiding yourself under a blanket next to the baby.
• Continue singing songs that involve movement and interaction, like “If You’re Happy And You Know It.”
• Go on outings and explore the world together. Even just going to the grocery store can be an adventure for a baby. Narrate everything. Don’t worry about using words your baby doesn’t understand; eventually they will, and hearing lots of different words is good for them.

Older toddlers, who are 2 or 3 years old, are able to do more complicated versions of these games. They can do matching, sorting, and counting games, as well as imitation and movement games like “follow the leader” (you can get quite creative and silly with that one).

As much as you can, give yourself over to play and have fun. Work and chores can wait, or you can actually involve young children in chores, making that more fun for both of you. Checking social media can definitely wait.

Playing with your child is an investment in your child’s future — and a great way to build your relationship and make both of you happy.

About the Author

Claire McCarthy, MD, Senior Faculty Editor, Harvard Health Publishing

Claire McCarthy, MD, is a primary care pediatrician at Boston Children’s Hospital, and an assistant professor of pediatrics at Harvard Medical School. In addition to being a senior faculty editor for Harvard Health Publishing, Dr. McCarthy … See Full Bio View all posts by Claire McCarthy, MD

You’re in a doctor’s office with a clipboard and a pile of medical forms on your lap. For the umpteenth time, you must now jot down your medical history — conditions, ongoing symptoms, past procedures, current medications, and even the health of family members.

But how much information should you include? Which details are most important? And why are you slogging through paper forms when a digital version likely exists? Put down your pen for a moment and take a breath. We have some answers.

Do you actually need to fill out the forms again?

In many cases, you do need to fill out medical history forms. That can be true even if you already have a digital record on file, known as an electronic medical record (EMR) or electronic health record (EHR).

The reason for collecting new information could be due to a variety of reasons:

• The health care provider might want an update, since information like medications or new health problems can change over time, or you might have missing or inaccurate information in your record.
• Different specialists need to know about different aspects of your health.
• Your EMR at one provider’s office might not be accessible to others because practices don’t always have compatible computer software.
• Some practices don’t want to rely on records created by other practices. They may not trust that they’re accurate.

What if you don’t want to fill out the forms?

“You don’t have to,” says Dr. Robert Shmerling, a rheumatologist and senior faculty editor at Harvard Health Publishing. “But the response from the practice might be, ‘How can we provide the best care if you don't provide the information?’ And if you persist, you run the risk of marking yourself — unfairly, perhaps — as uncooperative.”

What are the most important details in your medical history?

The most important details of your medical history include

• chronic or new symptoms and conditions
• past surgeries
• family medical history
• insurance information
• current prescription and over-the counter medicines, supplements, vitamins, and any herbal remedies or complementary medicines you use
• medication allergies
• vaccination history
• any screening tests you’ve had, so they won’t be prescribed unnecessarily
• any metal implants you have, which could affect screenings.

If you don’t know all of the details, try to get them from a previous doctor or hospital you’ve visited.

“In some cases, not having the information could be a problem. For example, I need to know if my patients have had certain vaccines or if they have medication allergies,” says Dr. Suzanne Salamon, associate chief of gerontology at Harvard-affiliated Beth Israel Deaconess Medical Center.

Which information might be less important?

Sometimes, leaving out certain details might not matter, depending on the purpose of your health visit. For example, your eye doctor doesn’t need to know that you broke your wrist when you were 18, had the flu last year, or had three C-sections. But they should know which medicines and supplements you take, and whether you have certain health conditions such as diabetes or high blood pressure.

Not sure what to leave in or out of your history? Dr. Salamon suggests that you at least focus on the big stuff: chronic symptoms and conditions that need ongoing treatment, medications and supplements you’re taking, and your family medical history.

“If you can, bring a copy of your medical history to all new doctor appointments. It could be written or printed from your patient portal or kept handy on a digital health app. That way, you’ll have it handy if you need to fill out medical forms or if the physician asks you questions about your medical history during an appointment,” Dr. Salamon advises.

How secure is the information you’re providing?

We trust health care professionals with our lives and our most private information, including our social security numbers (SSNs). SSNs are used to double-check your identity to avoid medical errors, and to make sure your insurance information is accurate and practices get paid.

Is it really safe to hand over the information? It’s supposed to be. A federal law called the Health Insurance Portability and Accountability Act (HIPAA) protects your health information with very strict rules about who can access it and how it can be shared.

“Medical practices take this very seriously,” Dr. Shmerling says. “They have lots of safeguards around personal health information, and routinely warn medical staff about not looking at or sharing information inappropriately — with the threat of being fired immediately if they do. Electronic health records usually track those who look at our information, so it's often not hard to enforce this.”

But no hospital or other entity can guarantee that your information is protected. That’s true of all information, especially with the constant threat of cyberattacks.

“So if you feel strongly about it, you can try saying that you’d rather not provide certain information and ask whether the practice can explain why it’s necessary,” Dr. Shmerling says. “It takes a certain amount of trust in the system that personal health information will be kept private, even though that may feel like taking a leap of faith.”

About the Author

Heidi Godman, Executive Editor, Harvard Health Letter

Heidi Godman is the executive editor of the Harvard Health Letter. Before coming to the Health Letter, she was an award-winning television news anchor and medical reporter for 25 years. Heidi was named a journalism fellow … See Full Bio View all posts by Heidi Godman

About the Reviewer

Howard E. LeWine, MD, Chief Medical Editor, Harvard Health Publishing

Dr. Howard LeWine is a practicing internist at Brigham and Women’s Hospital in Boston, Chief Medical Editor at Harvard Health Publishing, and editor in chief of Harvard Men’s Health Watch. See Full Bio View all posts by Howard E. LeWine, MD