What Is Alopecia Areata?
Alopecia areata is a disease that causes hair to fall out in small patches. It develops when the immune system attacks the hair follicles, resulting in hair loss. Sudden hair loss may occur on the scalp and other parts of the body. The condition rarely results in total hair loss, or alopecia universalis, but it can prevent hair from growing back. When hair does grow back, it’s possible for the hair to fall out again. The extent of hair loss and regrowth varies from person-to-person. There’s currently no cure for alopecia areata. However, there are treatments that may help hair grow back more quickly and that can prevent future hair loss. There are also resources available to help people cope with the disease.
What Are the Symptoms of Alopecia Areata?
The main symptom of alopecia areata is hair loss. Hair usually falls out in small round patches on the scalp. These patches are usually several centimeters or less. Hair loss might also occur on other parts of the body. You may first notice clumps of hair on your pillow or in the shower. However, other types of diseases can also cause hair to fall out in a similar pattern. Hair loss alone shouldn’t be used to diagnose alopecia areata.
In rare cases, some people may experience more extensive hair loss. This is usually an indication of another type of alopecia, such as:
alopecia totalis, which is the loss of all hair on the scalp
alopecia universalis, which is the loss of all hair on the entire body
The hair loss associated with alopecia areata is unpredictable and random. The hair may grow back at any time and then may fall out again. The extent of hair loss and regrowth varies greatly from person-to-person.
What Causes Alopecia Areata?
Alopecia areata is an autoimmune disease. An autoimmune disease develops when the immune system mistakes healthy cells for foreign substances. Normally, the immune system defends your body against foreign invaders, such as viruses and bacteria. If you have alopecia areata, however, your immune system mistakenly attacks your hair follicles. Hair follicles are the structures from which hairs grow. The follicles become smaller and stop producing hair, leading to hair loss.
Researchers don’t know what triggers the immune system to attack hair follicles, so the exact cause of this condition isn’t known. However, it most often occurs in people who have a family history of other autoimmune diseases, such as type 1 diabetes or rheumatoid arthritis. This is why some scientists suspect that genetics may contribute to the development of alopecia areata. They also believe that certain factors in the environment are needed to trigger alopecia areata in people who are genetically predisposed to the disease.
How Is Alopecia Areata Diagnosed?
Your doctor will review your symptoms to determine if you have alopecia areata. They may be able to diagnose alopecia areata simply by looking at the extent of your hair loss and by examining a few hair samples under a microscope.
Your doctor may also perform a scalp biopsy to rule out other conditions that cause hair loss, including fungal infections, such as tinea capitis. During a scalp biopsy, your doctor will remove a small piece of skin on your scalp for analysis.
Blood tests might be done if other autoimmune conditions are suspected. The specific blood test performed depends on the particular disorder your doctor suspects. However, your doctor will likely test for the presence of one or more abnormal antibodies. If these autoantibodies are found in your blood, it usually means that you have an autoimmune disorder.
Other blood tests that can help rule out other conditions include the following:
C-reactive protein and erythrocyte sedimentation rate
antinuclear antibody test
free and total testosterone
follicle stimulating and luteinizing hormon