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Anorexia (an-o-REK-see-uh) nervosa — often simply called anorexia — is an eating disorder characterized by an abnormally low body weight, intense fear of gaining weight and a distorted perception of body weight. People with anorexia place a high value on controlling their weight and shape, using extreme efforts that tend to significantly interfere with activities Read more…

Ankylosing spondylitis is an inflammatory disease that can cause some of the vertebrae in your spine to fuse together. This fusing makes the spine less flexible and can result in a hunched-forward posture. If ribs are affected, it may be difficult to breathe deeply. Ankylosing spondylitis affects men more often than women. Signs and symptoms Read more…

Anhidrosis is the inability to sweat normally. When you don’t sweat (perspire), your body can’t cool itself, which can lead to overheating and sometimes to heatstroke — a potentially fatal condition. Anhidrosis — sometimes called hypohidrosis — can be difficult to diagnose. Mild anhidrosis often goes unrecognized. Dozens of factors can cause the condition, including Read more…

Angina is a term used for chest pain caused by reduced blood flow to the heart muscle. Angina (an-JIE-nuh or AN-juh-nuh) is a symptom of coronary artery disease. Angina is typically described as squeezing, pressure, heaviness, tightness or pain in your chest. Angina, also called angina pectoris, can be a recurring problem or a sudden, Read more…

Angelman syndrome is a genetic disorder that causes developmental disabilities and neurological problems, such as difficulty speaking, balancing and walking, and, in some cases, seizures. Frequent smiles and outbursts of laughter are common for people with Angelman syndrome, and many have happy, excitable personalities. Angelman syndrome usually isn’t detected until parents begin to notice developmental Read more…

An aneurysm is an abnormal bulge or ballooning in your blood vessels. You may have one of several types of aneurysms, including: Aortic aneurysm. An aortic aneurysm forms in your aorta, a major blood vessel about the size of a garden hose. Your aorta carries blood from your heart to your vital organs. You may Read more…

Anemia is a condition in which you don’t have enough healthy red blood cells to carry adequate oxygen to your tissues. Having anemia may make you feel tired and weak. There are many forms of anemia, each with its own cause. Loss of blood is the most common cause of anemia. Anemia can be temporary Read more…

Anaphylaxis is a severe, potentially life-threatening allergic reaction. It can occur within seconds or minutes of exposure to something you’re allergic to, such as a peanut or the venom from a bee sting. The flood of chemicals released by your immune system during anaphylaxis can cause you to go into shock; your blood pressure drops Read more…