What is alopecia areata? Alopecia areata is a disease that causes hair loss. In alopecia areata, the immune system attacks the structures in skin that form hair (hair follicles). Alopecia areata usually affects the head and face, though hair can be lost from any part of the body. Hair typically falls out in small, round patches about the size of a quarter. In some cases, hair loss is more extensive.
What is osteonecrosis? Your bones are made up of living cells that need a blood supply to stay healthy. In osteonecrosis, blood flow to part of a bone is reduced. This causes death of bone tissue, and the bone can eventually break down and the joint will collapse. Osteonecrosis can happen to any bone, but most often it develops in the ends of long bones, such as the: Thigh bone. Upper arm bone. Less often, the bones of the elbows, ankles, feet, wrists, and hands are affected. When the disease involves part of a bone in a joint, it can
What is ankylosing spondylitis? Ankylosing spondylitis is a type of arthritis that causes inflammation in certain parts of the spine. Over time, this inflammation in the joints and tissues of the spine can cause stiffness. In severe cases, this may cause the bones in the spine to grow together, which can lead to a rigid spine that is difficult to bend. Many people with ankylosing spondylitis have mild episodes of back pain and stiffness that come and go. But others have severe, ongoing back pain and stiffness. Other symptoms also may develop if other areas of the body are affected
What is osteoporosis? Osteoporosis is a disease that causes bones to become weak and brittle. This increases your risk of broken bones (fractures). Osteoporosis is a “silent” disease because you may not have symptoms. You may not even know you have the disease until you break a bone. Breaks can occur in any bone but happen most often in: Hip bones. Vertebrae in the spine. Wrist. You can take steps to help prevent osteoporosis and broken bones by: Doing weight-bearing exercises, such as walking or dancing, and lifting weights. Not drinking too much alcohol. Quitting smoking, or not starting if
What is atopic dermatitis? Atopic dermatitis, often called eczema, is a chronic (long-lasting) disease that causes the skin to become inflamed and irritated, making it extremely itchy. Scratching leads to: Redness. Swelling. Cracking. “Weeping” clear fluid. Crusting. Scaling. In most cases, there are times when the disease is worse, called flares, followed by times when the skin improves or clears up entirely, called remissions. Atopic dermatitis is a common condition, and anyone can get the disease. However, it usually begins in childhood. Atopic dermatitis cannot be spread from person to person. No one knows what causes atopic dermatitis. Depending on
何謂異位性皮膚炎？ 異位性皮膚炎通常稱為濕疹。這是一種慢性（長期）疾病，造成皮膚炎症和刺激症狀，導致極度瘙癢。抓撓會引起： 發紅。 腫脹。 皸裂。 滲出透明液體。 結痂。 脫皮。 在大多數情況下，有時病情惡化（稱為急性發作），然後皮膚情況有所改善或症狀完全消失（稱為緩解）。 異位性皮膚炎是一種常見病症，任何人都可能患上。但異位性皮膚炎通常是在兒童期開始出現。異位性皮膚炎不會從一個人傳給另一個人。沒有人知道異位性皮膚炎的病因是什麼。根據症狀的嚴重程度，異位性皮膚炎患者的生活可能並不容易，但治療可幫助控制症狀。