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Patient-friendly health topic summaries from the US National Library of Medicine.
Ankylosing spondylitis (AS) is a type of arthritis of the spine. It causes inflammation (swelling) between your vertebrae (the bones that make up your spine) and the joints between your spine and pelvis. AS inflammation can cause…
Healthy kidneys clean your blood by removing excess fluid, minerals, and wastes. They also make hormones that keep your bones strong and your blood healthy. But if the kidneys are damaged, they don't work properly. Harmful wastes can…
Alzheimer's disease (AD) is the most common form of dementia among older people. Dementia is a brain disorder that seriously affects thinking and memory skills. If you have AD, it can impair your ability to reason or learn new skills…
Colorectal cancer is cancer that develops in the tissues of the colon or rectum. Your colon and rectum are part of your digestive system: • Your colon is the first and longest part of your large intestine. It absorbs water and some…
Your cornea is the outermost layer of your eye. It is clear and shaped like a dome. The cornea helps to shield the rest of the eye from germs, dust, and other harmful matter. It also helps your eye to focus. If you wear contact…
Pneumonia is an infection in one or both of the lungs. It causes the air sacs of the lungs to fill up with fluid or pus. It can range from mild to severe, depending on the type of germ causing the infection, your age, and your overall…
Heart failure means that your heart can't pump enough oxygen-rich blood to meet your body's needs. Heart failure doesn't mean that your heart has stopped or is about to stop beating. But without enough blood flow, your organs may not…
Rosacea is a long-term disease that affects your skin and sometimes your eyes. It causes redness and pimples. Rosacea is most common in women and people with fair skin. It most often affects middle-aged and older adults. In most…
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…
Ulcerative colitis (UC) is a disease that causes inflammation and sores, called ulcers, in the lining of the rectum and colon. It is one of a group of diseases called inflammatory bowel disease. UC can happen at any age, but it…
Psoriasis is a skin disease that causes itchy or sore patches of thick, red skin with silvery scales. You usually get them on your elbows, knees, scalp, back, face, palms and feet, but they can show up on other parts of your body.…
The urinary system is the body's drainage system for removing wastes and extra water. It includes two kidneys, two ureters, a bladder, and a urethra. Urinary tract infections (UTIs) are the second most common type of infection in the…
Parkinson's disease (PD) is a type of movement disorder. It happens when nerve cells in the brain don't produce enough of a brain chemical called dopamine. Sometimes it is genetic, but most cases do not seem to run in families.…
Cancer is a disease in which cells in the body grow out of control. Prostate cancer begins in the cells of the prostate. The prostate is a gland in the male reproductive system. It lies just below the bladder. It makes fluid that is…
Retinal disorders are conditions that affect the retina, the thin light-sensitive tissue at the back of your eye. The retina senses light and sends signals to your brain so you can see. Retinal disorders can cause blurred or distorted…
Pulmonary fibrosis is a condition in which the tissue deep in your lungs becomes scarred over time. This tissue gets thick and stiff. That makes it hard for you to catch your breath, and your blood may not get enough oxygen. Causes of…
Atrial fibrillation, also known as AFib or AF, is one of the most common types of arrhythmias. Arrhythmias are problems with the rate or rhythm of your heartbeat. They can cause your heart to beat too slowly, too fast, or in an…
Vitiligo causes white patches on your skin. It can also affect your eyes, mouth, and nose. It occurs when the cells that give your skin its color are destroyed. No one knows what destroys them. It is more common in people with…
Your adrenal glands are just above your kidneys. The outside layer of these glands makes hormones that help your body respond to stress and regulate your blood pressure and water and salt balance. Addison disease happens if the…
Celiac disease is a chronic (long-term) digestive and immune disorder that damages your small intestine. The damage may prevent your body from absorbing vitamins, minerals, and other nutrients from the food you eat. This can lead to…
Sjogren's syndrome, also called Sjogren's disease, is a chronic (long-lasting) autoimmune disease. When you have an autoimmune disease, your immune system attacks healthy tissues and organs by mistake. In Sjogren's syndrome, your…
A cyst is a fluid-filled sac. You may get simple kidney cysts as you age; they are usually harmless. There are also some diseases which cause kidney cysts. One type is polycystic kidney disease (PKD). It runs in families. In PKD, many…
Multiple sclerosis (MS) is a disease that affects your brain and spinal cord, also called the central nervous system. MS damages myelin, the protective coating around your nerve cells. Myelin helps nerves send messages quickly. When…
Melanoma is the most serious type of skin cancer. Often the first sign of melanoma is a change in the size, shape, color, or feel of a mole. Most melanomas have a black or black-blue area. Melanoma may also appear as a new mole. It…
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