Hepatitis is inflammation of the liver. Inflammation is swelling that happens when tissues of the body are injured or infected. It can damage your liver. This swelling and damage can affect how well your liver functions.

Hepatitis B is a type of viral hepatitis. It can cause an acute (short-term) or chronic (long-term) infection. People with an acute infection usually get better on their own without treatment. Some people with chronic hepatitis B will need treatment.

Thanks to a vaccine, hepatitis B is not very common in the United States. It is more common in certain parts of the world, such as sub-Saharan Africa and parts of Asia.

Hepatitis B is caused by the hepatitis B virus. The virus spreads through contact with blood, semen, or other body fluids from a person who has the virus.

Anyone can get hepatitis B, but the risk is higher in:

• Infants born to mothers who have hepatitis B
• People who inject drugs or share needles, syringes, and other types of drug equipment
• Sex partners of people with hepatitis B, especially if they are not using latex or polyurethane condoms during sex
• Men who have sex with men
• People who live with someone who has hepatitis B, especially if they use the same razor, toothbrush, or nail clippers
• Health care and public-safety workers who are exposed to blood on the job
• Hemodialysis patients
• People who have lived in or traveled often to parts of the world where hepatitis B is common
• People who have diabetes, hepatitis C, or HIV

Often, people with hepatitis B don't have symptoms. Adults and children over 5 are more likely to have symptoms than younger children.

Some people with acute hepatitis B have symptoms 2 to 5 months after infection. These symptoms can include:

• Dark yellow urine
• Diarrhea
• Fatigue
• Fever
• Gray- or clay-colored stools
• Joint pain
• Loss of appetite
• Nausea and/or vomiting
• Abdominal pain
• Yellowish eyes and skin, called jaundice

If you have chronic hepatitis B, you may not have symptoms until complications develop. This could be decades after you were infected. For this reason, hepatitis B screening is important, even if you have no symptoms. Screening means that you are tested for a disease even though you don't have symptoms. If you are at high risk, your health care provider may suggest screening.

In rare cases, acute hepatitis B can cause liver failure.

Chronic hepatitis B can develop into a serious disease that causes long-term health problems such as cirrhosis (scarring of the liver), liver cancer, and liver failure.

If you have ever had hepatitis B, the virus may become active again, or reactivated, later in life. This could start to damage the liver and cause symptoms.

To diagnose hepatitis B, your health care provider may use many tools to make a diagnosis:

• A medical history, which includes asking about your symptoms
• A physical exam
• Blood tests, including tests for viral hepatitis

If you have acute hepatitis B, you probably don't need treatment. Some people with chronic hepatitis B don't need treatment. But if you have a chronic infection and blood tests show that hepatitis B could be damaging your liver, you may need to take antiviral medicines.

The best way to prevent hepatitis B is to get the hepatitis B vaccine.

You can also reduce your chance of hepatitis B infection by:

• Not sharing drug needles or other drug materials
• Wearing gloves if you have to touch another person's blood or open sores
• Making sure your tattoo artist or body piercer uses sterile tools
• Not sharing personal items, such as toothbrushes, razors, or nail clippers
• Using a latex condom during sex. If your or your partner is allergic to latex, you can use polyurethane condoms.

If you think you have been in contact with the hepatitis B virus, see your health care provider right away. Your provider may give you a dose of the hepatitis B vaccine to prevent infection. In some cases, your provider may also give you a medicine called hepatitis B immune globulin (HBIG). You need to get the vaccine and the HBIG (if needed) as soon as possible after coming into contact with the virus. It is best if you can get them within 24 hours.

National Institute of Diabetes and Digestive and Kidney Diseases

Hyperthyroidism, or overactive thyroid, happens when your thyroid gland makes more thyroid hormones than your body needs.

Your thyroid is a small, butterfly-shaped gland in the front of your neck. It makes hormones that control the way the body uses energy. These hormones affect nearly every organ in your body and control many of your body's most important functions. For example, they affect your breathing, heart rate, weight, digestion, and moods. If not treated, hyperthyroidism can cause serious problems with your heart, bones, muscles, menstrual cycle, and fertility. But there are treatments that can help.

Hyperthyroidism has several causes. They include:

• Graves' disease, an autoimmune disorder in which your immune system attacks your thyroid and causes it to make too much hormone. This is the most common cause.
• Thyroid nodules, which are growths on your thyroid. They are usually benign (not cancer). But they may become overactive and make too much thyroid hormone. Thyroid nodules are more common in older adults.
• Thyroiditis, inflammation of the thyroid. It causes stored thyroid hormone to leak out of your thyroid gland.
• Too much iodine. Iodine is found in some medicines, cough syrups, seaweed and seaweed-based supplements. Taking too much of them can cause your thyroid to make too much thyroid hormone.
• Too much thyroid medicine. This can happen if people who take thyroid hormone medicine for hypothyroidism (underactive thyroid) take too much of it.

You are at higher risk for hyperthyroidism if you:

• Are a woman
• Are older than age 60
• Have been pregnant or had a baby within the past 6 months
• Have had thyroid surgery or a thyroid problem, such as goiter
• Have a family history of thyroid disease
• Have pernicious anemia, in which the body cannot make enough healthy red blood cells because it does not have enough vitamin B12
• Have type 1 diabetes or primary adrenal insufficiency, a hormonal disorder
• Get too much iodine, from eating large amounts of foods containing iodine or using iodine-containing medicines or supplements

The symptoms of hyperthyroidism can vary from person to person and may include:

• Nervousness or irritability
• Fatigue
• Muscle weakness
• Trouble tolerating heat
• Trouble sleeping
• Tremor, usually in your hands
• Rapid and irregular heartbeat
• Frequent bowel movements or diarrhea
• Weight loss
• Mood swings
• Goiter, an enlarged thyroid that may cause your neck to look swollen. Sometimes it can cause trouble with breathing or swallowing.

Adults over age 60 may have different symptoms than younger adults. For example, they may lose their appetite or withdraw from other people. Sometimes this can be mistaken for depression or dementia.

If hyperthyroidism isn't treated, it can cause some serious health problems, including:

• An irregular heartbeat that can lead to blood clots, stroke, heart failure, and other heart problems
• An eye disease called Graves' ophthalmopathy. It can cause double vision, light sensitivity, and eye pain. In rare cases, it can lead to vision loss.
• Thinning bones and osteoporosis
• Fertility problems in women
• Complications in pregnancy, such as premature birth, low birth weight, high blood pressure in pregnancy, and miscarriage

Your health care provider may use many tools to make a diagnosis:

• A medical history, including asking about symptoms
• A physical exam
• Thyroid tests, such as
  • TSH, T3, T4, and thyroid antibody blood tests
  • Imaging tests, such as a thyroid scan, ultrasound, or radioactive iodine uptake test. A radioactive iodine uptake test measures how much radioactive iodine your thyroid takes up from your blood after you swallow a small amount of it.

The treatments for hyperthyroidism include medicines, radioiodine therapy, and thyroid surgery:

• Medicines for hyperthyroidism include
  • Antithyroid medicines, which cause your thyroid to make less thyroid hormone. You probably need to take the medicines for 1 to 2 years. In some cases, you might need to take the medicines for several years. This is the simplest treatment, but it is often not a permanent cure.
  • Beta blocker medicines, which can reduce symptoms such as tremors, rapid heartbeat, and nervousness. They work quickly and can help you feel better until other treatments take effect.
• Radioiodine therapy is a common and effective treatment for hyperthyroidism. It involves taking radioactive iodine by mouth as a capsule or liquid. This slowly destroys the cells of the thyroid gland that produce thyroid hormone. It does not affect other body tissues. Almost everyone who has radioactive iodine treatment later develops hypothyroidism. This is because the thyroid hormone-producing cells have been destroyed. But hypothyroidism is easier to treat and causes fewer long-term health problems than hyperthyroidism.
• Surgery to remove part or most of the thyroid gland is done in rare cases. It might be an option for people with large goiters or pregnant women who cannot take antithyroid medicines. If you have all of your thyroid removed, you will need to take thyroid medicines for the rest of your life. Some people who have part of their thyroid removed also need to take medicines.

If you have hyperthyroidism, it's important not to get too much iodine. Talk to your health care provider about which foods, supplements, and medicines you need to avoid.

NIH: National Institute of Diabetes and Digestive and Kidney Diseases

Hypothyroidism, or underactive thyroid, happens when your thyroid gland doesn't make enough thyroid hormones to meet your body's needs.

Your thyroid is a small, butterfly-shaped gland in the front of your neck. It makes hormones that control the way the body uses energy. These hormones affect nearly every organ in your body and control many of your body's most important functions. For example, they affect your breathing, heart rate, weight, digestion, and moods. Without enough thyroid hormones, many of your body's functions slow down. But there are treatments that can help.

Hypothyroidism has several causes. They include:

• Hashimoto's disease, an autoimmune disorder where your immune system attacks your thyroid. This is the most common cause.
• Thyroiditis, inflammation of the thyroid
• Congenital hypothyroidism, hypothyroidism that is present at birth
• Surgical removal of part or all of the thyroid
• Radiation treatment of the thyroid
• Certain medicines
• In rare cases, a pituitary disease or too much or too little iodine in your diet

You are at higher risk for hypothyroidism if you:

• Are a woman
• Are older than age 60
• Have had a thyroid problem before, such as a goiter
• Have had surgery to correct a thyroid problem
• Have received radiation treatment to the thyroid, neck, or chest
• Have a family history of thyroid disease
• Were pregnant or had a baby in the past 6 months
• Have Turner syndrome, a genetic disorder that affects females
• Have pernicious anemia, in which the body cannot make enough healthy red blood cells because it does not have enough vitamin B12
• Have Sjogren's syndrome, a disease that causes dry eyes and mouth
• Have type 1 diabetes
• Have rheumatoid arthritis, an autoimmune disease that affects the joints
• Have lupus, a chronic autoimmune disease

The symptoms of hypothyroidism can vary from person to person and may include:

• Fatigue
• Weight gain
• A puffy face
• Trouble tolerating cold
• Joint and muscle pain
• Constipation
• Dry skin
• Dry, thinning hair
• Decreased sweating
• Heavy or irregular menstrual periods
• Fertility problems in women
• Depression
• Slowed heart rate
• Goiter, an enlarged thyroid that may cause your neck to look swollen. Sometimes it can cause trouble with breathing or swallowing.

Because hypothyroidism develops slowly, many people don't notice symptoms of the disease for months or even years.

Hypothyroidism can contribute to high cholesterol. In rare cases, untreated hypothyroidism can cause myxedema coma. This is a condition in which your body's functions slow down to the point that it becomes life-threatening.

During pregnancy, hypothyroidism can cause complications, such as premature birth, high blood pressure in pregnancy, and miscarriage. It can also slow the baby's growth and development.

Your health care provider may use many tools to make a diagnosis:

• A medical history, including asking about your symptoms
• A physical exam
• Thyroid tests, such as
  • TSH, T3, T4, and thyroid antibody blood tests
  • Imaging tests, such as a thyroid scan, ultrasound, or radioactive iodine uptake test. A radioactive iodine uptake test measures how much radioactive iodine your thyroid takes up from your blood after you swallow a small amount of it.

The treatment for hypothyroidism is medicine to replace the hormone that your own thyroid can no longer make. About 6 to 8 weeks after you start taking the medicine, you will get a blood test to check your thyroid hormone level. Your health care provider will adjust your dose if needed. Each time your dose is adjusted, you'll have another blood test. Once you find the right dose, you will probably get a blood test in 6 months. After that, you will need the test once a year.

If you take your medicine according to the instructions, you usually should be able to control the hypothyroidism. You should never stop taking your medicine without talking with your health care provider first.

If you have Hashimoto's disease or other types of autoimmune thyroid disorders, you may be sensitive to harmful side effects from iodine. Talk to your health care provider about which foods, supplements, and medicines you need to avoid.

Women need more iodine when they are pregnant because the baby gets iodine from the mother's diet. If you are pregnant, talk with your health care provider about how much iodine you need.

NIH: National Institute of Diabetes and Digestive and Kidney Diseases

You have two kidneys, each about the size of your fist. They are near the middle of your back, just below the rib cage. Inside each kidney there are about a million tiny structures called nephrons. They filter your blood. They remove wastes and extra water, which become urine. The urine flows through tubes called ureters. It goes to your bladder, which stores the urine until you go to the bathroom.

Most kidney diseases attack the nephrons. This damage may leave kidneys unable to remove wastes. Causes can include genetic problems, injuries, or medicines. You have a higher risk of kidney disease if you have diabetes, high blood pressure, or a close family member with kidney disease. Chronic kidney disease damages the nephrons slowly over several years. Other kidney problems include:

• Cancer
• Cysts
• Stones
• Infections

Your doctor can do blood and urine tests to check if you have kidney disease. If your kidneys fail, you will need dialysis or a kidney transplant.

NIH: National Institute of Diabetes and Digestive and Kidney Diseases

Obesity is a disease that means having too much body fat. It is different from being overweight, which means weighing too much. Both terms mean that your weight is greater than what's considered healthy for your height.

Body Mass Index (BMI) measures how much you weigh compared to how tall you are. An adult who has a BMI of 30 or more is considered to have obesity. Severe obesity is having a BMI of 40 or higher. Obesity increases your risk for many other diseases and health problems, especially if the extra body fat is carried around the waist.

Obesity happens over time from taking in more calories (through food and drinks) than used up from physical activity and daily living. Your body stores the extra calories as fat. The right balance between calories and activity is different for everyone.

There are many different factors that can affect your body weight. Certain medicines or medical conditions may affect your weight. Other factors include your:

• Genetic makeup
• Eating habits
• Sex
• Race or ethnicity
• Physical activity level

To find out if you have obesity, your health care provider may:

• Ask about your health history, which may include reviewing your weight history, weight-loss efforts, and how physically active you are.
• Do a physical exam, which may include checking your height, weight, and vital signs, as well as listening to your heart and lungs.
• Order blood tests or other imaging tests, which may include checking any known health problems, as well as for other weight-related diseases and health conditions.
• Calculate your BMI, to check your risk for certain diseases. The higher your BMI, the higher your risk. BMI does not distinguish between fat, muscle, and bone mass. It may also overestimate body fat in athletes or those with a muscular build, or underestimate body fat in older persons, or others who have lost muscle.
• Check your waist size, since a large waistline, with more body fat around your abdomen (belly) rather than your hips, increases your risk for weight-related health problems.

Having a larger body size can make your heart work harder, put extra pressure on your joints, and may increase your risk for many health conditions, including:

• Type 2 diabetes.
• Heart disease.
• High blood pressure.
• Stroke.
• Metabolic syndrome.
• Osteoarthritis.
• Sleep apnea.
• Pregnancy problems.
• Fertility problems.
• Some cancers.

If you have obesity, losing even 5 to 10% of your weight can delay or prevent some of these diseases. For example, that means losing 10 to 20 pounds if you weigh 200 pounds.

Treatment plans for obesity may depend on your overall weight, other health conditions, and your willingness to participate in a weight-loss plan.

Your provider can tell you what a healthy weight is for you, help you set goals, and give you tips on how to lose weight. They may refer you to other providers that specialize in nutrition or weight loss to help you make realistic goals and provide support.

Possible treatments may include:

• Dietary changes and exercise goals to help you learn how to adopt healthy nutrition, exercise, and lifestyle changes to lose weight safely and keep it off long term.
• Counseling or support groups can give you encouragement and help you understand what's behind weight changes.
• Weight-loss medicines to treat obesity.
• Weight loss procedures or surgery if you have severe obesity or serious obesity-related health problems and have not been able to lose enough weight.

A healthy lifestyle that includes healthy eating patterns and regular physical activity can help you lose weight and lower your chance of developing complications related to obesity.

NIH: National Institute of Diabetes and Digestive and Kidney Diseases